Category: Waf bypass headers

Waf bypass headers

Once you understand the issue, you should be able to restore the fire to your defenses. We will show you how. The potential devastation of this vulnerability lies in both the breadth of those affected and the impact for each affected organization.

XXE was the only new issue of the set that was introduced based on direct data evidence from the security issues database. Adding to the scale of the concern, a single application can contain several linked XML interpreters processing the data from different application tiers.

This potential ability to inject an external entity at various points in the application stack via an XML interpreter is what makes XXE so dangerous. However, there is more to the story.

waf bypass headers

However, we need to understand how XXE is a vulnerability. The problem may be one of human error and not, as much, with the technology. The contents of the file specified in the link replace it in the document body. A correctly configured XML interpreter will either not accept a document with XML links for processing or will validate the links and their sources. If the validation is missing, an arbitrary file can be loaded via the link and integrated into the document body as in the example above.

The settings of a diligent WAF usually prevent it from reading the contents of the linked files. This is strategy generally makes sense since the WAF itself may otherwise also become a target of an attack.

This means that a WAF, which has not read the contents of the file, will not read the declarations of the entity present in the document. The links to unknown entities, in turn, will stop the XML parser causing an error. Fortunately, there is an easy way to guard against this kind of a bypass.

With the help of such encodings, it is easy to bypass a WAF using regular expressions since, in this type of WAF, regular expressions are often configured only for a one-character set. Exotic encodings may also be used to bypass diligent WAFs as they are not always able to process all the encodings listed above. In the previous section, we demonstrated that the encoding of the document is typically specified by its first bytes.

In this case, some parsers change the encoding so that the beginning of the file has one set of characters, and the rest of it is in another encoding. That said, different parsers may switch the encoding at different times. A Java parser javax. A diligent WAF can protect against the attacks in such documents reliably only if it never processes them at all.

The libxml2 parser treats the document as valid, however, the Java engine from javax. Vice versa, the document is valid in terms of the javax. Standard application configuration has become known and exploited by hackers.This blog post introduces a technique to send HTTP requests using encoding. This method should be added to the list of tests performed to measure effectiveness of a web application firewall WAF. We have only tested this technique against the following web server setups during this research.

As a result, other web servers and setups might potentially behave in the same way:. If you have tested web applications or dealt with HTTP requests, the Content-Type header should be familiar as it is used to indicate the media type of the message [2].

This header can be used in request and response messages. The charset values are normally important when dealing with responses as they can change the behaviour of web browsers.

This is useful to show multiple languages or to perform obfuscated attacks such as cross-site scripting. However, this parameter can also be sent in requests! Although using different character encoding parameters in requests is not new, we could not find any evidence that this was used to bypass WAF solutions previously.

Signature-based WAF products that use blacklists do not normally understand different character encodings. We have used an example to explain the encoding behaviour. We want to use another encoding that can obfuscate our payload in order to smuggle it through the WAF. We could use utf or utf and add null characters between the current characters; however, it was blocked by our WAF due to the use of null characters.

Additionally, encodings such as euc-kr were not useful to smuggle the requests properly as they converted some of the higher ASCII characters to the? Therefore, we used an encoding such as ibm [4] that changed the position of ASCII characters which was perfect for obfuscation. On IIS, the query string parameters were also required to be encoded using the same process.

As a result, the original HTTP request was changed to:. The above request could be used to smuggle our payload through a WAF. The following table shows the support of different character encodings on the tested systems when messages could be obfuscated using them :. The set of character encodings were collected from [5] - this list should not be considered exhaustive as to the encodings supported by the web servers.

If it is not possible to decode the message bodies correctly to perform further analysis, WAFs should only allow requests that use known character encodings. NCC Group uses cookies to ensure the best experience on our website. You can use this tool to change your cookie settings. These cookies are necessary for the website to function and cannot be switched off in our systems. They are usually only set in response to actions made by you, which amount to a request for services, such as setting your privacy preferences, logging in, or filling in forms.

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waf bypass headers

If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again. Add headers to all Burp requests to bypass some WAF products. This extension will automatically add the following headers to all requests. I have been adding features rapidly and it is very possible that the above will be in the code by the time anyone actually reads this.

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Web Application Firewall Bypassing by Khalil Bijjou

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waf bypass headers

Go back. Launching Xcode If nothing happens, download Xcode and try again. This branch is 8 commits ahead of codewatchorg:master. Pull request Compare. Latest commit Fetching latest commit….

waf bypass headers

X-Originating-IP: This is probably the top bypass technique i the tool. It isn't unusual for a WAF to be configured to trust itself The "Content-Type" header can remain unchanged in each request, removed from all requests, or by modified to one of the many other options for each request. The "Host" header can also be modified.

Poorly configured WAFs might be configured to only evaluate requests based on the correct FQDN of the host found in this header, which is what this bypass targets. The request type option allows the Burp user to only use the remaining bypass techniques on the given request method of "GET" or "POST", or to apply them on all requests.

This can be used to bypass poorly written rules that rely on path information. The path obfuscation feature modifies the last forward slash in the path to a random value, or by default does nothing. The last slash can be modified to one of many values that in many cases results in a still valid request but can bypass poorly written WAF rules that rely on path information. The parameter obfuscation feature is language specific. The "Set Configuration" button activates all the settings that you have chosen.

All of these features can be combined to provide multiple bypass options. HTTP Requests Smuggling - Automatically perform an HTTP request smuggling attack on each request where a dummy request is added to the beginning and the real smuggled request is added at the end. Note I am not maintaining the Python version. You signed in with another tab or window. Reload to refresh your session.

You signed out in another tab or window. Added support for X-Client-IP. Mar 26, Avoid the directory name affecting the name of the resultant jar by e….If you've got a moment, please tell us what we did right so we can do more of it. Thanks for letting us know this page needs work.

We're sorry we let you down. If you've got a moment, please tell us how we can make the documentation better. You also can configure CloudFront to return a custom error page when a request is blocked. Allow all requests except the ones that you specify — This is useful when you want CloudFront or an Application Load Balancer to serve content for a public website, but you also want to block requests from attackers.

Block all requests except the ones that you specify — This is useful when you want to serve content for a restricted website whose users are readily identifiable by properties in web requests, such as the IP addresses that they use to browse to the website. Count the requests that match the properties that you specify — When you want to allow or block requests based on new properties in web requests, you first can configure AWS WAF to count the requests that match those properties without allowing or blocking those requests.

When you're confident that you specified the correct properties, you can change the behavior to allow or block requests. Additional protection against web attacks using conditions that you specify. You can define conditions by using characteristics of web requests such as the following:.

Strings that appear in requests, either specific strings or string that match regular expression regex patterns. Rules that can allow, block, or count web requests that meet the specified conditions.

Alternatively, rules can block or count web requests that not only meet the specified conditions, but also exceed a specified number of requests in any 5-minute period. AWS Shield Advanced incurs additional charges. The Firewall Manager service automatically applies your rules and other security protections across your accounts and resources, even as you add new accounts and resources.

Javascript is disabled or is unavailable in your browser. Please refer to your browser's Help pages for instructions. Did this page help you? Thanks for letting us know we're doing a good job! You can define conditions by using characteristics of web requests such as the following: IP addresses that requests originate from.

Country that requests originate from. Values in request headers.Take a look at our Documentation section for full details about every Burp Suite tool, function and configuration option. This extension add headers to all Burp requests to bypass some WAF products. The following headers are automatically added to all requests:. You can also download them from here, for offline installation into Burp. Please note that extensions are written by third party users of Burp, and PortSwigger Web Security makes no warranty about their quality or usefulness for any particular purpose.

Support Center. Getting Started. Getting Started Home. Burp Suite Documentation Take a look at our Documentation section for full details about every Burp Suite tool, function and configuration option. Knowledge Base. Extensions can be written in Java, Python or Ruby. BApp Store. Release Notes. The following headers are automatically added to all requests: X-Originating-IP: This is probably the top bypass technique i the tool. It isn't unusual for a WAF to be configured to trust itself The "Content-Type" header can remain unchanged in each request, removed from all requests, or by modified to one of the many other options for each request.

The "Host" header can also be modified. Poorly configured WAFs might be configured to only evaluate requests based on the correct FQDN of the host found in this header, which is what this bypass targets. The request type option allows the Burp user to only use the remaining bypass techniques on the given request method of "GET" or "POST", or to apply them on all requests. This can be used to bypass poorly written rules that rely on path information. The path obfuscation feature modifies the last forward slash in the path to a random value, or by default does nothing.

The last slash can be modified to one of many values that in many cases results in a still valid request but can bypass poorly written WAF rules that rely on path information. The parameter obfuscation feature is language specific. The "Set Configuration" button activates all the settings that you have chosen. All of these features can be combined to provide multiple bypass options.

API documentation Sample extensions. Writing your first Burp Suite extension View community discussions about Extensibility. You can view the source code for this BApp by visiting our GitHub page.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. If nothing happens, download GitHub Desktop and try again.

If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again. Add headers to all Burp requests to bypass some WAF products. This extension will automatically add the following headers to all requests.

I have been adding features rapidly and it is very possible that the above will be in the code by the time anyone actually reads this. Skip to content. Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.

Sign up. Java Python. Java Branch: master. Find file. Sign in Sign up. Go back. Launching Xcode If nothing happens, download Xcode and try again.

Latest commit Fetching latest commit…. X-Originating-IP: This is probably the top bypass technique i the tool.

XSS Filter Evasion Cheat Sheet

It isn't unusual for a WAF to be configured to trust itself The "Content-Type" header can remain unchanged in each request, removed from all requests, or by modified to one of the many other options for each request.

The "Host" header can also be modified.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Server Fault is a question and answer site for system and network administrators. It only takes a minute to sign up.

Bypassing web application firewalls using HTTP headers

My concern is a WAF bypass. What do you think is the best way to whitelist so that the aws load balancers only takes traffic from the sucuri waf?

My ec2s are running on nginx. Looks like NLB does not have a security group and nginx may not see the real ip of the user. Any thoughts? I also need the features of ALB thats why I have both.

I can roll out my own nginx load balancers but I'd like less problem and I need it for some other AWS features. You can use that to limit which IPs traffic can from from. That relies on NLB not messing with that information. If so this would work well with the ALB security groups. Another approach is that Securi most likely sets the X-Forwarded-For header.

Once that's done you have another method using Nginx that lets you block all hosts other than those you allow. Sign up to join this community. The best answers are voted up and rise to the top.

Home Questions Tags Users Unanswered. Asked 1 year, 10 months ago. Active 1 year, 10 months ago. Viewed times. With NLB, the security group of the instances is used for access control. That's why the NLB itself has no security group. To help clarify: Where is this WAF located, logically and physically? If so, your configuration may eventually fail if the ALB needs to scale up or down or in or out.

From the route53, the A records are pointed to the sucury ip. The sucury then talks to the NLB. Yes, I see the problem, here. Since the NLB target group is connecting to addresses, not instances, you lose the ability to use security groups on the ALB, because the source address is always the NLB address.

Can the Sucuri not use a hostname instead of static IPs to connect to the backend?


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