Tag Archives: penetration testing

Burp Extension – Juice Shop Routes

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When it comes to testing for security within our web applications, we often look to creating simple tools to help speed things up. They also help provide a consistent way to help identify known patterns. For those that haven’t been following, I have been doing a few posts about getting the OWASP Juice Shop application up and running. In this post, I want to introduce a simple burp extension I created to help with a few of the challenges presented in the OWASP Juice Shop.

The Challenge

The OWASP Juice Shop has multiple challenges built into it to help guide the user along in finding web applications. The app is written as a single page app (SPA) and is a little different than your traditional applications. Rather than make a full page request for everything you click, instead the application just makes API calls. In short, the entire UI is returned on the first load of the application.

There are multiple challenges within the Juice Shop that require the user to access specific URLs that are not available via a menu or link. For example (and I don’t want to directly give away answers to the challenge here), imaging visiting the contact screen. If you click the menu item for contact us, it will update the URL in the address bar to be like /#/contact. So I don’t have to actually click a link to access the contact us page, I could just update that URL directly in the address bar.

Finding the Routes

So how do you find the URLs that are available to access? There are multiple ways of doing this. First, of course, you could try to just fuzz them. This is good if the URLs are not available anywhere for us to find. Fortunately, this Angular application embeds the different routes within the client-side code. It uses a RouteProvider object to do this.

With a little digging, you can find this information in the /dist/juice-shop.min.js file. This is a pretty large file and looking through it can be a little tough. Searching for RouteProvider will bring you to the route definitions.

A Burp Extension

As a professional web app tester, I spend a lot of time using Burp Suite as my web proxy. It allows me to easily view and intercept all the traffic my browser sends back and forth to the server. Another cool feature is it allows building your own extensions to solve just this type of problem. Of course, you probably wouldn’t just create an extension for this one piece or a specific app. Instead, the hope would be that it would become helpful for other applications that use angular’s route provider object. This way, when I go to test other sites, I may get this information right there in my scanner results.

I built a quick little burp extension that looks for the routeProvider object and then, if found, pulls out each route defined. The code can be found at https://github.com/jamesjardine/juiceshoproutes. The code that performs all the tasks are in the BurpExtender.java file.

Once the extension is built into a JAR file it can be added into Burp. Note that this only works for Burp Pro because it uses the passive scanner. To install it, just navigate to the “Extender” tab and click the Add button. Then select the Jar file you created:

Be 0

Here is a quick run down of what it does:

  • Looks to see if the response from the server contains the phrase $routeProvider. If it finds this phrase it then gets the start offset and the end of the object by identifying the next ] character.
  • It then loops through the specific body text looking for a match to e.when. This basically defines when the URL matches X, load a specific template.
  • Each route that is identified is then displayed in an unordered list.
  • When you visit the Target Tab and select your site, click on the Issues tab to look for Angular Routes.

This is just a quick example of how building custom burp extensions can help increase your efficiency or help provide some additional coverage for known patterns within applications.

————–POTENTIAL SPOILER INFO BELOW ——————–

IF YOU ARE WANTING TO TRY THIS OUT WITHOUT SEEING THE RESPONSE FIRST STOP READING HERE!!!

There is no interaction needed to trigger this scan except for just visiting the initial page of the Juice Shop site. The Issues tase will look like:

Be screen1

If you look at the response, you will see the following image:

Be 2

In the above image you can see the highlighted area showing where the RouteProvder routes are defined. In the following image, you can see the advisory screen which indicates the formatted list of routes that are available:

Be 3

OWASP 2017 Changes

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When I talk to people about application security, the most recognized topics is the OWASP Top 10. If you haven’t heard of the top 10, or need a refresher, you can get the full list at:

https://www.owasp.org/images/7/72/OWASP_Top_10-2017_%28en%29.pdf.pdf

The OWASP Top 10 is on a three year update cycle. We had the list in 2010, 2013 and now the latest is 2017. You may be wondering why it is 2017 rather than 2016. I think that is a question a lot of people had. In any case, the list made it out to final release after the initial draft was rejected. Now that it is here, we can analyze it and see how it affects us and our organizations.

https://www.youtube.com/watch?v=kfDuxwFScOE

What I think sticks out more to me this update over previous updates is the removal of some pretty common flaws based on my experience. In the past we have seen flaws move up or down on the risk level, or get combined, but not as much removed. In 2017, we saw two items get removed:

  • Cross-site Request Forgery
  • Unvalidated Redirects and Forwards

I find these items interesting because I see them on most of the assessments I do. Let’s take a quick look at them.

Cross-site Request Forgery

CSRF can be a pretty serious flaw based on its context. It is the ability to force the victim’s browser to make requests to another site they are authenticated too without their knowledge. An example of a higher-risk context is the ability to change the victim’s email address on their profile. If the system doesn’t have two factor authentication or other safe guards, changing the email address can lead to the ability to request a password reset. In many situations, this can lead to easily taking over the victim’s account.
This is just one example of how CSRF can be used. The good news is that many newer frameworks provide some level of CSRF protection built-in. So in many applications it is not as prevalent. However, based on my experience, not everyone is using the latest frameworks. Due to this, I still find this on a lot of the assessments I do.

Unvalidated Redirects and Forwards

Unvalidated Redirects is often viewed as a low risk issue. In many cases, it may represent a low risk. There are some situations that make unvalidated redirects fairly dangerous. A good example is the redirect often performed by login forms. A common feature of many applications is to redirect the user to a specific resource after logging in. To do this, a parameter in the URL specifies the path to be sent to. If the application allows redirecting to external sites, it is simple to set up a malicious site with the same look and feel as the expected site. If the victim uses your link with the reference to your malicious site they may be presented with your fake login page after successfully logging into the real site. The victim may believe they have mistyped their password and just login again without checking the URL, leading to account takeover.

We also saw to access control findings get merged into one. This change makes a lot of sense when you look at each item. They are both regarding access control issues.

With the removal and merging, the list has brought on three new vulnerabilities:

  • XML External Entities (XXE)
  • Insecure Deserialization
  • Insufficient Logging and Monitoring

XML External Entities (XXE)

XML External Entities is a vulnerability that takes advantage of how XML Parsers interpret the supplied XML. In this case, it is possible to reference other resources outside of the XML document. A common scenario is the ability to read other files on the web server, such as the /etc/passwd file. This vulnerability also may allow a denial of service attack to occur due to embedding specific entities. This vulnerability obviously relies on the application parsing XML data. If your application is parsing XML, it is recommended to make sure the parser is ignoring or blocking DTDs. If your parser doesn’t have that option, or you need to allow some DTDs, make sure your input validation is limiting those to only acceptable ones.

Insecure Deserialization

Insecure Deserialization occurs when you are deserializing data that has not been properly sanitized. This occurs because we assume that the data serialized has not been modified. When the data is modified, it could be executed during the deserialization process to perform commands. To help prevent this, make sure you are enforcing strict data checks on the objects that have been serialized. I do not see this very often in many of the assessments I do. Just depends on the application as many do not use much serialization.

Insufficient Logging and Monitoring

When I talk to people and ask them about logging, the first response, or usually the only response, is related to troubleshooting. There is no doubt that troubleshooting is critical for any application. If the application is not running as expected, users may leave, transactions may get lost, or a myriad of other issues may occur. Logging is for much more than just troubleshooting. Proper logging of security related events can help identify an attack while it is occurring as well as help identify what happened after the fact. It can be very difficult to identify what data was accessed or how if there are no logs indicating such information. It is good that we are seeing more attention called to this practice, although it can be a complex one to implement and verify. Don’t forget that once you start logging security events, they must be monitored to take action.

Wrap Up

Changes to the OWASP Top 10 isn’t something new. We know it will happen and it may require some adjustment to what we are doing internally. While we do see items drop or get added, it just highlights that the top 10 is a mere starting point of security. Every organization should have their list of top 10 risks. Don’t limit yourself to these short lists. They are to help identify the highest risks and implement them in a feasible way. Application security doesn’t happen overnight. There has to be a starting point and then a path to mature.

Listen to the podcast on this topic. http://podcast.developsec.com/developsec-podcast-91-owasp-top-10-2017-thoughts

Two-Factor Authentication Considerations

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There was a recent article talking about how a very small percentage of google users actually use 2-factor authentication. You can read the full article at http://www.theregister.co.uk/2018/01/17/no_one_uses_two_factor_authentication/

Why 2-Factor

Two-factor authentication, or multi-factor authentication, is a valuable step in the process to protect accounts from unauthorized users. Traditionally, we have relied just on a username/password combination. That process had its own weaknesses that many applications have moved to improve. For example, many sites now require “complex” passwords. Of course, complex is up for debate. But we have seen the minimum password length go up and limitations on using known weak passwords go up. Each year we see lists of the most common passwords to not use, some being 123456 or Password. I hope no one is using these types of passwords. To be honest, I don’t know of any sites I use that would allow this type of password. So many these days require a mix of characters or special characters.

https://www.youtube.com/watch?v=YxXebkpSLr8

The above controls are meant to help reduce the risk of someone just guessing your password, there are other controls to help try to limit brute forcing techniques. Many accounts offer account lockout after X number of invalid attempts. There are other controls that we also see implemented around protecting the username/password logic. None of these controls help protect against a user reusing passwords on another site that may be compromised. They also do not protect against a user falling for a social engineering attack to trick them into sharing their passwords. To help combat this, many sites will implement a second factor beyond username/password.

The idea of the second factor is that even if you have the username and password, you will not have this other piece of information. In most cases, it is a value that changes every 60 seconds or so, and is delivered over a protected channel. For example, the token used may be sent via SMS, a voice call, or created through a phone application like the Google Authenticator application. So even if the attacker is able to get your password, via a breach, brute force, or just lucky guessing, in theory they would not have access to that second factor.

Why Are People Not Using It?

So why do people not enable the second factor on their Google accounts? Unfortunately, the presentation didn’t appear to explain that, which makes sense since it is difficult to know why people do or do not do certain things. I think there may be a few reasons for it that we will briefly touch on.

First, I think many people just are not aware of enabling the second factor. To be fair, it is sort of buried down in settings that may be difficult to find if you are not really looking for it. If it is not front and center, then there is a much smaller chance people will go seeking it out. To add to the issue, many people really don’t understand what 2-factor authentication means or how it really helps them. Sure, in security we get it, but that doesn’t mean everyone else does. How do we make it more prominent that this is a positive security feature? Many users will already be aware of 2-factor if they use online banking as most of those have started enforcing it.

Many people think that two factor authentication is a burden or it will slow their access down. This is usually not the case unless the application has implemented it poorly. Many sites will allow you to save your computer so you don’t need to enter the 2nd factor every time you access the site. However, it will require it if you access from a different computer.

To complicate things, other applications may not support signing in with 2 factors, like your email client. In these cases, you have to generate an app password which can be very confusing to many users, especially those that are not technically savvy.

There may be a chance that users don’t think they need to protect their email accounts, that it is not sensitive. If you just use email to communicate with friends and receive junk mail, what could be so bad, right? Most people forget that things like password resets are performed using an email account. Having control of an email account provides a lot of control over a lot of things. While it may seem small, email is an important function to protect.

If you are using Gmail, I recommend configuring 2-factor authentication. The following video walks through setting it up using SMS (Although there are other options as well):

Demo- Google 2 factor

If you are developing applications, I recommend looking into providing the option of 2-factor authentication. When you do this, make sure that you are promoting its use in a positive way. If you already have 2-factor with your application, can you run a report to determine what percentage of users are actually using it? If that number is low, what steps can you take to increase them?

Don’t assume that any application is not worthy of the extra security. Many applications are already providing 2-factor and that number will just increase. While we still have the password, we will always be looking for ways to add more protection. When implemented properly, it is simple for the end user, but effective in increasing security. If your user base is not taking advantage of the option, take the time to assess why that is and how it can be improved.

As I was writing this up, I ran into an interesting situation with 2-factor that sparked some more thoughts. When looking to support 2-factor authentication and not using SMS, take careful consideration to the applications you may choose to support. On the Apple App Store alone there are over 200 different authenticator apps available. Some are interchangeable while others are not. This can be another barrier in users choosing to enable 2-factor authentication.

Tinder Mobile Take-Aways

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While browsing through the news I noticed an article talking about the Tinder mobile app and a privacy concern. You can read the article at https://www.consumerreports.org/privacy/tinder-app-security-flaws-put-users-privacy-at-risk/. To summarize what is considered the issue is that the mobile application does not transmit the photos that you see using HTTPS. This means that anyone on the same connection can see the traffic and, ultimately, see the photos you are presented. From my understanding, it doesn’t appear the potential attacker can tell who the user is that is viewing these photos as the rest of the traffic is properly using HTTPS.

We have discussed the move to all HTTPS multiple times on this blog and we are seeing a lot of sites making the switch. With web applications it is easy to see if the site is using HTTPS or not with the indicators near the address bar. Of course, these indicators are often confusing to most, but at least we have the ability to see the status. With a mobile application it is much more difficult to tell if data is transmitted using HTTPS or not because there is no visible indicator. Instead, one needs to view the raw traffic or use a web proxy to see how the data is transmitted. This can be misleading to many people because the assumption is that the data is protected because it is hidden under more layers.

In this instance, the ability to see these photos may not be considered that sensitive by many. Assuming that anyone can create an account and see the photos doesn’t make them a secret. People have opted to post their images for others to find them on the network. Of course, level of sensitivity is in the eye of the beholder these days. Another issue that is potentially possible in this situation is that the attacker could manipulate that image traffic to show a different image. This could lead to the end user seeing a different image than the one expected. The usefulness of this could be called into question at any type of large scale.

The take-away here is that when we are building applications we must take care in understanding how we are transmitting all of our data to determine what needs to be protected. As I mentioned, there is already a push to make everything HTTPS all the time. If you have decided not to use HTTPS for your connections, have you documented the reasons? What does your threat model tell you about the risks with that data and its communication. How does that risk line up with your acceptance procedures.

Another interesting tidbit came out of the article mentioned above. In addition to seeing the actual photos, they found it was possible to identify whether or not the end user liked or disliked the photo by comparing the network traffic. The interesting part about this part is that those decisions were encrypted when transmitted. The key point here is that the traffic for each decision was a set size and the sizes were different for like and dislike. By viewing the traffic after seeing a photo, it is possible to determine which ones were liked based on the size of the requests. In this case, it still doesn’t identify the end user that is using the application.

We don’t typically spend a lot of time analyzing the size of the requests we send in the event someone may try to determine what actions we are taking over an encrypted channel. Most of the time these actions are not possible to determine, or the level of effort is way above what is realistic. The easy solution would be to make sure all traffic was encrypted and we wouldn’t be able to know what images were liked or disliked. Maybe it would be possible to still see the difference, but with no way to tie it to specific images. The other option is to attempt to pad the requests so that they are all the same size. This would be for highly sensitive systems as the complexity may not be worth the benefit.

Of course, all of this is based on the attacker being on the same network as the end user so they can intercept or view the traffic in the first place. In the case of a public place, it might just be easier to hover over your shoulder and watch you use the app then intercept the traffic and guess at who is using it.

Both of these topics are good conversation starters within your organization. They help us realize that even just one request that doesn’t use HTTPS may be seen and could raise an issue. It also helps us to see that sometimes even encrypted data can be determined, but that doesn’t mean it is a high risk. Each situation is different and should be properly analyzed to determine the risk it creates for the company and the organization.

New Year’s Resolutions

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Here we are, the start of another year. As we reflect on 2017, this is where we really start to focus on what lies ahead in 2018. The new year is always interesting because it usually doesn’t affect our build cycles or releases. With the exception of accounting for vacations. Yet, this is the time of year where many people get re-focused and motivated to change old habits or try something new.

Listen to the Podcast:

As I look back on 2017, there were a lot of news headlines that focused around security. So many of them highlighting breaches, many termed “mega” breaches. The trend of hyped up headlines glorifying monster breaches will likely continue through 2018 and beyond. We know that breaches can, or will, happen. We have seen examples of different techniques used to gain unauthorized access to data. This won’t change, and will most likely become more prevalent going forward. The amount of information available to potential attackers is enormous, making our job of application security that much more important.

One of the biggest lessons to take away from 2017 is that privacy is important. In addition, private data is not limited to PCI or HIPAA. All sorts of data can be considered private and require the custodian to take proper steps to protect it. It doesn’t matter if the data is held by a Fortune 500 company or a one-person shop. To someone, that data is worth something. As we look into 2018, this reminds us that we must understand what data we have. We must know what type of regulations it may fall under, what applications contain it, and how we are protecting it. Just because data may not fall under a regulation doesn’t mean it should be overlooked. In the end, it is the expectation of our customers and clients that we will handle their data responsibly.

Protecting this data is not about how much money you spend or what tools you buy. Every organization is different. Every application development team is different. I encourage everyone to take the time to research and understand what your team needs to be successful. As in the past, throughout the year I will be posting thoughts on different application security topics. If you have any questions or topics, feel free to share them with me. Looking for someone to talk to about application security? Reach out. I have services available to help organizations and individuals reach new heights and solve problems.

What are your New Year’s Resolutions when it comes to application security?

JavaScript in an HREF or SRC Attribute

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The anchor (<a>) HTML tag is commonly used to provide a clickable link for a user to navigate to another page. Did you know it is also possible to set the HREF attribute to execute JavaScript. A common technique is to use the onclick event of the anchor tab to execute a JavaScript method when the user clicks the link. However, to stop the browser from actually redirecting the HREF can be set to javascript:void(0);. This cancels the HREF functionality and allows the JavaScript from the onclick to execute as expected.

In the above example, notice that the HREF is set with a value starting with “javascript:”. This identifier tells the browser to execute the code following that prefix. For those that are security savvy, you might be thinking about cross-site scripting when you hear about executing JavaScript within the browser. For those of you that are new to security, cross-site scripting refers to the ability for an attacker to execute unintended JavaScript in the context of your application (https://www.owasp.org/index.php/Cross-site_Scripting_(XSS)).

I want to walk through a simple scenario of where this could be abused. In this scenario, the application will attempt to track the page the user came from to set up where the Cancel button will redirect to. Imagine you have a list page that allows you to view details of a specific item. When you click the item it takes you to that item page and passes a BackUrl in the query string. So the link may look like:

https://developsec.com/item.php?backUrl=/items.php

On the page, there is a hyperlink created that sets the HREF to the backUrl property, like below:

<a href=”<?php echo $_GET[“backUrl”];?>”>Back</a>

When the page executes as expected you should get an output like this:

<a href=”/items.php”>Back</a>

There is a big problem though. The application is not performing any type of output encoding to protect against cross-site scripting. If we instead pass in backUrl=”%20onclick=”alert(10); we will get the following output:

<a href=”” onclick=”alert(10);“>Back</a>

In the instance above, we have successfully inserted the onclick event by breaking out of the HREF attribute. The bold section identifies the malicious string we added. When this link is clicked it will prompt an alert box with the number 10.

To remedy this, we could (or typically) use output encoding to block the escape from the HREF attribute. For example, if we can escape the double quotes (” -> &quot; then we cannot get out of the HREF attribute. We can do this (in PHP as an example) using htmlentities() like this:

<a href=”<?php echo htmlentities($_GET[“backUrl”],ENT_QUOTES);?>”>Back</a>

When the value is rendered the quotes will be escapes like the following:

<a href=”&quot; onclick=&"alert(10);“>Back</a>

Notice in this example, the HREF actually has the entire input (in bold), rather than an onclick event actually being added. When the user clicks the link it will try to go to https://www.developsec.com/” onclick=”alert(10); rather than execute the JavaScript.

But Wait… JavaScript

It looks like we have solved the XSS problem, but there is a piece still missing. Remember at the beginning of the post how we mentioned the HREF supports the javascript: prefix? That will allow us to bypass the current encodings we have performed. This is because with using the javascript: prefix, we are not trying to break out of the HREF attribute. We don’t need to break out of the double quotes to create another attribute. This time we will set backUrl=javascript:alert(11); and we can see how it looks in the response:

<a href=”javascript:alert(11);“>Back</a>

When the user clicks on the link, the alert will trigger and display on the page. We have successfully bypassed the XSS protection initially put in place.

Mitigating the Issue

There are a few steps we can take to mitigate this issue. Each has its pros and many can be used in conjunction with each other. Pick the options that work best for your environment.

  • URL Encoding – Since the HREF is meant to be a URL, you could perform URL encoding. URL encoding will render the javascript benign in the above instances because the colon (:) will get encoded. You should be using URL encoding for URLs anyway, right?
  • Implement Content Security Policy (CSP) – CSP can help limit the ability for inline scripts to be executed. In this case, it is an inline script so something as simple as ‘Content-Security-Policy:default-src ‘self’ could be sufficient. Of course, implementing CSP requires research and great care to get it right for your application.
  • Validate the URL – It is a good idea to validate that the URL used is well formed and pointing to a relative path. If the system is unable to parse the URL then it should not be used and a default back URL can be substituted.
  • URL White Listing – Creating a white list of valid URLs for the back link can be effective at limiting what input is used by the end user. This can cut down on the values that are actually returned blocking any malicious scripts.
  • Remove javascript: – This really isn’t recommended as different encodings can make it difficult to effectively remove the string. The other techniques listed above are much more effective.

The above list is not exhaustive, but does give an idea of ways to help reduce the risk of JavaScript within the HREF attribute of a hyper link.

Iframe SRC

It is important to note that this situation also applies to the IFRAME SRC attribute. it is possible to set the SRC of an IFRAME using the javascript: notation. In doing so, the javascript executes when the page is loaded.

Wrap Up

When developing applications, make sure you take this use case into consideration if you are taking URLs from user supplied input and setting that in an anchor tag or IFrame SRC.

If you are responsible for testing applications, take note when you identify URLs in the parameters. Investigate where that data is used. If you see it is used in an anchor tag, look to see if it is possible to insert JavaScript in this manner.

For those performing static analysis or code review, look for areas where the HREF or SRC attributes are set with untrusted data and make sure proper encoding has been applied. This is less of a concern if the base path of the URL has been hard-coded and the untrusted input only makes up parameters of the URL. These should still be properly encoded.

Insulin Pump Vulnerability – Take-aways

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It was recently announced that there were a few vulnerabilities found with some insulin pumps that could allow a remote attacker to cause the pump to distribute more insulin than expected. There is a great write up of the situation here. When I say remote attack, keep in mind that in this scenario, it is someone that is within close proximity to the device. This is not an attack that can be performed via the Internet.

This situation creates an excellent learning opportunity for anyone that is creating devices, or that have devices already on the market. Let’s walk through a few key points from the article.

The Issue

The issue at hand was that the device didn’t perform strong authentication and that the communication between the remote and the device was not encrypted. Keep in mind that this device was rolled out back in 2008. Not to say that encryption wasn’t an option 8 years ago, for these types of devices it may not have been as main stream. We talk a lot about encryption today. Whether it is for IoT devices, mobile applications or web applications, the message is the same: Encrypt the communication channel. This doesn’t mean that encryption solves every problem, but it is a control that can be very effective in certain situations.

This instance is not the only one we have seen with unencrypted communications that allowed remote execution. It wasn’t long ago that there were computer mice and keyboards that also had the same type of problem. It also won’t be the last time we see this.

Take the opportunity to look at what you are creating and start asking the question regarding communication encryption and authentication. We are past the time where we can make the assumption the protocol can’t be reversed, or it needs special equipment. If you have devices in place currently, go back and see what you are doing. Is it secure? Could it be better? Are there changes we need to make. If you are creating new devices, make sure you are thinking about these issues. Communications is high on the list for all devices for security vulnerabilities. Make sure it is considered.

The Hype, or Lack of

I didn’t see a lot of extra hype over the disclosure of this issue. Often times, in security, we have a tendency to exaggerate things a bit. I didn’t see that here and I like it. At the beginning of this post I mentioned the attack is remote, but still requires close physical proximity. Is it an issue: Yes. is it a hight priority issue: Depends on functionality achieved. As a matter of fact, the initial post about the vulnerabilities states they don’t believe it is cause for panic and the risk of wide scale exploitation is relatively low. Given the circumstances, I would agree. They even go on to say they would still use this device for their children. I believe this is important because it highlights that there is risk in everything we do, and it is our responsibility to understand and choose to accept it.

The Response

Johnson and Johnson released an advisory to their customers alerting them of the issues. In addition, they provided potential options if these customers were concerned over the vulnerabilities. You might expect that the response would downplay the risk, but I didn’t get that feeling. They list the probability as extremely low. I don’t think there is dishonesty here. The statement is clear and understandable. The key component is the offering of some mitigations. While these may provide some inconvenience, it is positive to know there are options available to help further reduce the risk.

Attitude and Communication

It is tough to tell by reading some articles about a situation, but it feels like the attitudes were positive throughout the process. Maybe I am way off, but let’s hope that is true. As an organization it is important to be open to input from 3rd parties when it comes to the security of our devices. In many cases, the information is being provided to help, not be harmful. If you are the one receiving the report, take the time to actually read and understand it before jumping to conclusions.

As a security tester, it is important for the first contact to be a positive one. This can be difficult if you have had bad experiences in the past, but don’t judge everyone based on previous experiences. When the communication starts on a positive note, the chances are better it will continue that way. Starting off with a negative attitude can bring a disclosure to a screeching halt.

Conclusion

We are bound to miss things when it comes to security. In fact, you may have made a decision that years down the road will turn out to be incorrect. Maybe it wasn’t at the time, but technology changes quickly. We can’t just write off issues, we must understand them. Understand the risk and determine the proper course of action. Being prepared for the unknown can be difficult, but keeping a level head and honest will make these types of engagements easier to handle.

Jardine Software helps companies get more value from their application security programs. Let’s talk about how we can help you.

James Jardine is the CEO and Principal Consultant at Jardine Software Inc. He has over 15 years of combined development and security experience. If you are interested in learning more about Jardine Software, you can reach him at james@jardinesoftware.com or @jardinesoftware on twitter.

Login Forms and HTTP

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Does your application have a login form? Do you deliver it over HTTPS to protect the username and password while being transmitted to the server? If you answered yes to both of those questions, are you sure?

Many years ago, before there was a huge push for HTTPS all the time, it was common practice for many applications to load a login form using HTTP, but then submit the form over HTTPS. This was accomplished by setting the action attribute of the form to the full HTTPS version of the site.

<form action=”https://www.somesite.com/login” method=”post”>

There was a flaw in this setup. The flaw is not even with the submission of your credentials. Instead, the issue is how that login form is initially loaded. Remember we said that the initial request was HTTP? The belief was that because the loading of the form doesn’t transmit any sensitive data, it would be ok to use HTTP. You could even take a trip back to the performance wars during that time stating that HTTP was much faster to load. (We learned a lot of the years).

The problem is that if there is a malicious user (attacker) on your same network that is able to redirect your traffic through them they could manipulate the initial load of the page. Imagine if the attacker intercepted your request to the login page (initial load) and changed the action of the form to a different site?

<form action=”http://myevilsite.com/login” method=”post”>

Notice how the new form submission will go to a different site, not even using HTTPS. From the end user’s point of view they wouldn’t even know the form was going to send their credentials to a different site.

Over the years, we have seen the use of this methodology shrinking down. Many sites are now loading their login forms all over HTTPS. As a matter of fact, many sites are 100% HTTPS.

But Wait!!

There is another angle to this that is often overlooked, but works very similar. Does your site allow it to be loaded into frames? I have seen a lot of sites that have been including another application’s login form using either frame sets or frames. The issue, the container site is often a simple marketing or branding site and runs over HTTP.

Like the above example, the HTTP site is including a frame reference to an HTTPS site. Again, the login form submission is still correct. However, it is possible that the attacker from the previous scenario could intercept the containing page and change the reference for the login frame. In this case, the attacker would most likely create a page that is identical to the real login form and point the frame to that one. The user would have no idea that the authentication page was incorrect, because it would look like the original. When the user submits their credentials, they would then be submitted to the malicious user instead of the real site.

It is recommended to not allow your site to be hosted within a sub frame. There are plenty of articles that discuss frame busting techniques and you could look into the X-Frame-Options header as well. If your form doesn’t load in a frame then your risk of being included on a non-secure site is reduced. For all other scenarios, there isn’t a lot of reason to not be using HTTPS from end to end. By securing all of the transactions, it reduces the risk that an attacker can easily manipulate that traffic.

How Serious is Username Enumeration

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Looking through Twitter recently, I caught a very interesting stream that started with the following message:

There were quite a few replies, and a good discussion on the topic of the seriousness of username enumeration flaws. 140 characters is difficult to share a lot of thoughts, so I thought this would actually be a great post.

What is Username Enumeration?

Username Enumeration refers to the ability to determine not only if a username is valid within a specific application, but also to automate the process of identifying a multiple valid usernames. The most common example of username harvesting is on the application logon form. The culprit, the unsuccessful login error message. This happens because the application creators want to be helpful and let the user know what went wrong. When the message is not generic, for example “unsuccessful login”, it may indicate if the user exists or not. An example message would be “Username does not exist”. This is bad. A better response would be “Username or password are incorrect”. This is a much more generic answer and doesn’t give away whether or not the username is valid.

Where do we find Username Enumeration?

As I mentioned above, the login screen is one of the most common locations we find username harvesting. However, it is not the only place. Probably the two next biggest offenders are the Forgot Password screen and the User Registration screen. With all three of these screens, it is critical to realize that the display message is not the only way to detect username harvesting. In reality, it is any difference that comes back between an invalid and a valid user. This could be the error message, a status code that is different, timing attacks, or a myriad of other techniques. Don’t just think about the error message. That one is typically the easiest, but not the only method for identification. API calls may also be a source for username harvesting.

The Login Form

The login form is typically vulnerable through the error message. To help protect the login form, make sure that the application returns a generic error message for any error situation. A good example of this is “Your login attempt was unsuccessful. If you continue to have trouble, contact support.” This message is good for invalid username, invalid password, and even account lockout.

The Forgot Password Form

The forgot password screen is usually vulnerable due to poor forget password design. Most systems ask for the username/email address and if correct, do one of the following: 1) Ask for secret security questions, 2) Display a message that an email has been sent to the email address on record. Unfortunately, for an incorrect username, the system returns an error message that the username was not found. To correct this problem, it is possible to either ask for more than just the username (something that is private to the account), or just always display the “email has been sent” message. In this configuration, no matter what, the email is sent form is displayed.

The Registration Form

The registration screen is a bit more tricky because, in most situations, you need to be able to alert the user that their username is already in use. Unlike the other two scenarios, the error message can’t really be fixed. One option on a registration screen is to enable the use of a CAPTCHA to attempt preventing automation attacks. If implemented properly the attacker would be slowed down in their enumeration making things more difficult. It may not make it impossible, but the goal is to reduce the risk.

How is Username Enumeration Used?

There are a few ways that username enumeration becomes important to an attacker. First, it is a good technique to limit down the list of possible usernames to attempt password attacks on. One example on twitter gave the example of taking a list of 100 million usernames and reducing it to 100 thousand to perform actual password guessing on. In this scenario, the attackers are also attempting to take advantage of weak password complexity, or just bad password hygiene. Often times, they may take the top 3 or 4 common passwords and try those against all of the valid usernames to see if anyone is using them.

The second way that username enumeration is used is for social engineering attacks. Or, at least, more targeted social engineering attacks. If the attacker knows that the user has an account on a specific application, it can make phone calls and emails much more convincing and ultimately more successful. Limiting emails to 100,000 users rather than 100 million helps reduce the overhead and reduces the chances of getting detected.

Somewhat related to social engineering attacks, this information could also be used to target individuals based on moral values. Remember the Ashley Madison breach that happened a while back. Depending on what the username is in use, it may be possible to identify people that use a particular site and sort of out them, or blackmail them. Think of other sites people may not want to be public about visiting.

How Serious is it?

I bet you didn’t think we would ever get here. It is important to understand how the attackers may be using a vulnerability to start to determine how serious it really is. Unfortunately, there isn’t an easy answer that fits every application. As I mentioned above, with poor password hygiene, the risk would be raised if someone is using one of those top 4 passwords. It also depends on the type of system, the type of data collected, the functionality the application performs, etc. No systems are created or rated equally.

In the scenario above for the login screen guessing the top 4 passwords, let’s not forget that it is possible to try all 100 million usernames from our list. Sure, it is helpful to reduce it down to only valid usernames, but the attack is still possible without the username enumeration flaw. In the ideal setup, the application would have some form of detection system in place that might detect all of the unsuccessful login attempts, but that is the ideal. It is not common enough to see that type of detection implemented in many applications. Without that detection, and a little crafty rate limiting by an attacker, the difference between 100 million attempts and 100,000 attempts is really just time.

As we all know, social engineering attacks are the latest and greatest. Any help we provide attackers in that arena is a step backwards for us. This could lead to a bigger problem and that is why we need to understand the issues we are trying to solve.

Should we fix it?

If we had all the time and resources in the world, the answer would be an easy “yes”. Unfortunately, we don’t have that. This really comes down to your organization’s risk assessments and priorities. I always like to provide the recommendation to resolve the issue, as it makes for a better application overall. Depending on your situation, the fix may not be straight forward or easy. You may have other higher priority items that need to be worked on. Remember, for the password attack, it is really a combination of a weak password issue as well. It is not just username harvesting on its own.

Take the opportunity to review how you are auditing and logging these types of events within your application. In some cases we may see logging occurring, but then there is no auditing of those logs. Detection and response is critical in helping reduce the risk of these types of flaws.

Continuing Forward

Username enumeration is a risk to any application. It is up to the organization to understand their business to determine how big or small that risk is. This isn’t something that should just be ignored, but it also doesn’t mean it is something that is a critical finding. Don’t just write the finding off. Use that as an opportunity to discuss the functionality, understand how it works, and determine the best course of action for the organization and the users.

Username enumeration is typically fairly simple to test for and should be worked into the QA testing cycle. Take the time to discuss with the architects, developers, business analysts, and the testers how the organization can test for this and reduce the risk.

Jardine Software helps companies get more value from their application security programs. Let’s talk about how we can help you.

James Jardine is the CEO and Principal Consultant at Jardine Software Inc. He has over 15 years of combined development and security experience. If you are interested in learning more about Jardine Software, you can reach him at james@jardinesoftware.com or @jardinesoftware on twitter.

Understanding the “Why”

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If I told you to adjust your seat before adjusting your mirror in your car, would you just do it? Just because I said so, or do you understand why there is a specific order? Most of us retain concepts better when we can understand them logically.

Developing applications requires a lot of moving pieces. An important piece in that process is implementing security controls to help protect the application, the company, and the users. In many organizations, security is heavily guided by an outside group, i.e.. the security group or 3rd party testers.

Looking at an external test, or even a test by an internal security team, often the result is a report containing findings. These findings typically include a recommendation to guide the application team in a direction to help reduce or mitigate the finding. In my experience, the recommendations tend to be pretty generic. For example, a username harvesting flaw may come with a recommendation to return the same message for both valid and invalid user names. In most cases, this is a valid recommendation as it is the reason for the flaw.

But Why? Why does it matter?

Working with application teams, it quickly becomes clear the level of understanding regarding security topics. The part that is often missing is the Why. Sure, the team can implement a generic message (using the username harvesting flaw above) and it may solve the finding. But does it solve the real issue? What are the chances that when you come back and test another app for this same development team that the flaw may exist somewhere else? When we take the time to really explain why this finding is a concern, how it can be abused, and start discussing ways to mitigate it, the team gets better. Push aside the “sky is falling” and take the time to understand the application and context.

As security professionals we focus too much on fixing a vulnerability. Don’t get me wrong, the vulnerability should be fixed, but we are too focused. Taking a step back allows us to see a better approach. It is much more than just identifying flaws. It is about getting the application teams to understand why they are flaws (not just because security said so) so they become a consideration in future development. This includes the entire application team, not just developers. Lets look at another example.

An Example

Let’s say that you have a change password form that doesn’t require the current password. As a security professional, your wheels are probably spinning. Thinking about issues like CSRF. From a development side, the typical response “Why do I need to input my password when I just did that to login to change my password?” While the change will most likely get made, because security said it had too, there is still a lack of understanding from the application team. If CSRF was your first reason, what if they have CSRF protections already in place? Do you have another reason? What about if the account is hijacked somehow, or a person sits at the user’s desk and they forgot to lock their PC? By explaining the reasoning behind the requirement, it starts to make sense and is better received. It dominos into a chance that the next project that is developed will take this into consideration.

When the business analysts sits down to write the next change password user story, it will be a part of it. Not because security said so, but because they understand the use case better and how to protect it.

If you are receiving test results, take the time to make sure you understand the findings and the WHY. It will help providing a learning objective as well as reduce the risk of not correcting the problem. Understand how the issue and remediation effects your application and users.

James Jardine is the CEO and Principal Consultant at Jardine Software Inc. He has over 15 years of combined development and security experience. If you are interested in learning more about Jardine Software, you can reach him at james@jardinesoftware.com or @jardinesoftware on twitter.

Originally posted at https://www.jardinesoftware.com