Web Application on Insinuator.net - Bold Statements

Vulnerability Disclosure: JWT Authentication Bypass in OpenID Connect Authenticator for Tomcat

Tue, 17 Feb 2026 00:00:00 +0000

During a customer project we identified an issue with the validation of JWT tokens that allowed us to bypass the authentication by using unsigned tokens with arbitrary payloads. During analysis we found out that this is caused by a vulnerability within the library OpenID Connect Authenticator for Tomcat.

OpenID Connect Authenticator for Tomcat between versions 2.0.0 and 2.5.0, as well as the current state on branch master contain a security flaw (introduced with commit 64e9a99) that allows attackers to bypass JWT signature validation easily.

Cookie Prefixes – The Lesser Known Cookie Security Feature

Tue, 08 Apr 2025 00:00:00 +0000

When you’re analyzing web applications as a pentester or reading pentest reports about web applications, you will often see findings regarding cookies missing certain security flags. The Set-Cookie HTTP header and the JavaScript document.cookie API allow to use, for example, the flags Secure, Path, and Domain. Common audit and pentest tools will tell you when your web application does not or just insecurely implements these cookie flags.

However, they do not provide optimal security even when using these flags correctly. However, there are mitigations available that partly solve the issues.

Solving client-side controls once and for all

Fri, 01 Apr 2022 00:00:00 +0000

Missing server-side validation consistently scores a place in the OWASP Top 10. Browsers nowadays offer a lot of ways to easily implement client-side controls, increasing the usability by a lot. They automatically detect missing fields or invalid characters in your input fields and may even validate user input against a regular expressions.

However, these controls should only be considered as usability features. When sending data to a back-end system the application must always ensure data integrity by implementing encodings, validations and filters. Even for small applications this is a painful and tedious process. For each possible input, developers together with security experts have to carefully identify the context of each field, how the input is going to be used and what data requirements are present.

Yet Another Information Disclosure?

Tue, 24 Apr 2018 00:00:00 +0000

Hey there, for those of you that roll your eyes when writing the nth Information Disclosure Finding in a report, here is a short story of how such information helped compromising a system.

In a recent penetration we found a hidden debug page which disclosed information about internal parameters. Along with database connection strings and key material there was a username and a user home parameter disclosed on said debug page.

New Methods for Exploiting ORM Injections in Java Applications (HITB16)

Thu, 02 Jun 2016 00:00:00 +0000

The HITBSecConf or “Hack In The Box” in Amsterdam is a well known security conference in Europe. We also attended this year too, and there were quite some interesting talks at the HITBSecConf16 conference. One of the talks was about “New Methods for Exploiting ORM Injections in Java Applications” by the security researchers Mikhail Egorov and Sergey Soldatov.

I. What is Object-Relational Mapping (ORM)?

ORM stands for Object-Relational Mapping, which is a technique that automatically converts data from a relational database management system (RDBMS) into objects. This is often used in business applications of today.

Classic Web Vulns Found in Google Search Appliance 7.4

Wed, 23 Mar 2016 00:00:00 +0000

Hi all,

I’ve recently found some sort of classic web vulnerabilities in the Google Search Appliance (GSA) and as they are now fixed [0][1][2], I’d like to share them with you.

First of all, some infrastructure details about the GSA itself. The GSA is used by companies to apply the Google search algorithms to their internal documents without publishing them to cloud providers. To accomplish this task, the GSA provides multiple interfaces including a search interface, an administrative interface and multiple interfaces to index the organization’s data.

How to test Kerberos authenticated web applications?

Thu, 18 Feb 2016 00:00:00 +0000

First of all: This is not an in-depth Kerberos how-to, nor is this tutorial about the different aspects of web application testing. This tutorial is just to give support in testing Kerberos authenticated web applications. The goal is to hand over the right tools and steps to be able to perform the configuration and be able to test the application.

When to use it?
When there is a 401 server response with the header “WWW-Authenticate: Negotiate”. This can either mean Kerberos or NTLM authentication is needed. It is possible to distinguish them by looking at valid authenticated client traffic. As a simple reminder: The NTLM Authorization header will always start with the value “TlRM…”, the Kerberos Authorization header will always start with “YII…”. For further information this link is recommend.
In this tutorial the term “Kerberos authentication” will be used. There are other terms sometimes used like SPNEGO, SSO or integrated authentication.

Web Hacking Special Ops Workshop @ TR16

Tue, 26 Jan 2016 00:00:00 +0000

Trooper!

You passed Hacking 1on1 with flying colors?

You evade web application firewalls as they would be opened doors?

You have successfully exploitated CVE-2015-8769?

Then it’s time for the next challenge! Follow us down the rabbit hole to the not so well known attacks against modern web applications.

At Troopers16 we will be presenting the second iteration of our WebHackingSpecialOps workshop in which more advanced techniques to break current web application technologies will be explained. On the first day there will be an introduction that gives a quick overview on the well-known attacks like SQLi, XSS and XSRF. Then attacks will be shown that build upon these “old” vectors including blind/clientside SQLi, NoSQLi and some specialties on NodeJS, the javascript based server-side runtime. Next to these technical topics several formal subjects like 3rd library handling and a guideline on how to deploy TLS in a secure way will be given. Especially the 3rd party library chapter since they have become more and more relevant, as in the near past several major vulnerabilities in such libraries were found which gave attackers the chance to break web applications that were based on these. This shows that even though developers do a great job and developer companies get familiar with secure development lifecycles, there are still problems depending on the used technologies that cannot be addressed easily. One example of such a vulnerability is the object deserialization flaw in the Apache Commons Collections library, which was discovered at the beginning of 2015 and got attention in November, when two researchers presented their talk on AppSecCali2015 and showed how easy remote code execution can be done through this kind of flaw. The details of all kind of object deserialization (as almost all current scripting/high level programming languages support this feature) will be part of our course. Next to these topics a deep-dive into current crypto algorithms, their usecases concerning webapplications and their flaws will be given. Within every part of this course several demos and hands-on exercises will be done, so every attendee will be able to apply new knowledge directly. Don’t miss this chance to improve, Trooper!

XML External Entity (XXE) Injection in Apache Batik Library [CVE-2015-0250]

Sat, 21 Mar 2015 00:00:00 +0000

During one of our latest web application code review projects I came across a vulnerability for which I think it is worth to speak about. It is an injection based attack against XML parsers which uses a rarely required feature called external entity expansion. The XML specification allows XML documents to define entities which reference resources external to the document and parsers typically support this feature by default. If an application parses XML input from untrusted sources and the parsing routine is not properly configured this can be exploited by an attacker with a so called XML external entity (XXE) injection. A successful XXE injection attack could allow an attacker to access the file system, cause a DoS attack or inject script code (e.g. Javascript to perform an XSS attack).

ERNW’s Top 9 Burp Plugins

Mon, 25 Aug 2014 00:00:00 +0000

In the context of an internal evaluation, we recently had a look at most of the burp plugins available from the BApp store. The following overview represents our personal top 9 plugins, categorized in “Scanner Extensions”, “Manual Testing” and “Misc” in alphabetic order:

Scanner Extensions

ActiveScan++

This plugin adds some tests for Dynamic code injection, Host header attacks (password reset poisoning, cache poisoning, DNS rebinding), OS command injection and Relative path overwrite. In some internal tests, it seemed to deliver what it promises.

Django Image Validation Vulnerability

Fri, 16 May 2014 00:00:00 +0000

Hi!

In the course of a recent penetration test, we came across an Image validation vulnerability in Django when using the Python-Imaging-Library (PIL) which we want to explain in this post.

Everybody who doesn’t know what Django and/or the PIL is:
Django is a framework to create web applications with Python (comparable to Rails or Zend). The PIL is a powerful standard python library which provides a toolset to modify, display and verify images of many different formats.

Cross-Site Request Forgery with Cross-Origin Resource Sharing

Fri, 02 Aug 2013 00:00:00 +0000

During one of our last projects in a large environment we encountered an interesting flaw. Although it was not possible to exploit it in this particular context, it’s worth to be mentioned here. The finding was about Cross-Site Request Forgery, a quite well-known attack that forces a user to execute unintended actions within the authenticated context of a web application. With a little help of social engineering (like sending a link via email, chat, embedded code in documents, etc…) an attacker may force the user to execute actions of the attacker’s choice.

The Web Application Firewall Story continues

Fri, 22 Jun 2012 00:00:00 +0000

Some days ago another advisory related to a web application firewall (WAF) product was published. This time the product Airlock by Ergon was affected by a vulnerability that combines Encoding and NULL Byte attacks to circumvent the pattern based detection engine. We have described these attacks in detail in our newsletter “Web Application Firewall Security and The Swiss Army Knife for Web Application Firewalls” because they belong to a well known category of attacks against WAFs.

SQL Injection Testing for Business Purposes Part 2

Mon, 28 May 2012 00:00:00 +0000

Take Care of the Database

There are some database specifics, every pentester should be aware of, when testing for and exploiting SQLi vulnerabilities. Besides the different string concatenation variants already covered above, there are some other specifics that have to be considered and might turn out useful in some circumstances. For example with Oracle Databases, every SELECT statement needs a following FROM statement even if the desired data is not stored within a database. So when trying to extract e.g. the DB username using a UNION SELECT statement, the DUAL table may be utilized, which should always be available. Another point, if dealing with MySQL, is the possibility to simplify the classic payload

The 5 Myths of Web Application Firewalls

Mon, 16 Apr 2012 00:00:00 +0000

Some days ago a security advisory related to web application firewalls (WAFs) was published on Full Disclosure. Wendel Guglielmetti Henrique found another bug in the IBM Web Application Firewall which can be used to circumvent the WAF and execute typical web application attacks like SQL injection (click here for details). Wendel talked already (look here) at the Troopers Conference in 2009 about the different techniques to identify and bypass WAFs, so this kind of bypass methods are not quite new.

tsakwaf 0.9.1 released

Sun, 11 Sep 2011 00:00:00 +0000

A few weeks ago, I released version 0.9 of a web application testing tool called tsakwaf (The Swiss Army Knife for Web Application Firewalls) together with an ERNW Newsletter about web application firewalls. tsakwaf is based on perl and supports fingerprinting of some supported WAFs and code generation methods to circumvent filter rules. Today, version 0.9.1 will be released, which adds SSL support for the WAF fingerprinting function (Big thanks to Simon Rich!) and a bug fix regarding the detection of WAF reactions which may lead to false positives. Additionally, I’m happy to announce that at least one talk at next year’s Troopers will cover attacks against WAFs (like this one from the 2009 edition) . So mark your calendar – Troopers12 will happen on 21^(st) and 22^(nd) March 2012, with the usual workshops before the conference and the round table sessions the day after – and enjoy playing with tsakwaf!

The 5 Myths of Web Application Firewalls

Mon, 27 Jun 2011 00:00:00 +0000