Writing secure code today is easier than making a mistake that would lead to an XXE vulnerability. While examining a library, I wondered: is its code truly secure? At first glance, everything appeared to be filtered, and the function didn’t have the attributes that could make it vulnerable.
However, I was able to exploit an almost impossible XXE vulnerability using a combination of techniques and features.
Continue readingEvery organization has printers. Sometimes, there are Xerox WorkCentre among them, large machines that can weigh more than 100 kilos or 220 lbs.
In this writeup, I will cover two unauthenticated RCE vulnerabilities that I discovered in these printers. Next, I’ll provide a checklist for protecting your printers against attacks.
Continue readingA year ago, I wondered what a malicious page with disabled JavaScript could do.
I knew that SVG, which is based on XML, and XML itself could be complex and allow file access. Is the Same Origin Policy (SOP) correctly implemented for all possible XML and SVG syntaxes? Is access through the file:// protocol properly handled?
Since I was too lazy to read the documentation, I started generating examples using ChatGPT.
Continue readingRecently, I came across an interesting ASP.NET application. It appeared to be secure, but it accidentally revealed its source code. Later, I found out that the used method is applicable to disclose code of many other .NET web applications.
Here are the details. If you just see an IIS or .NET app, this is for you.
Continue readingCross-Origin Resource Sharing (CORS) is a web protocol that outlines how a web application on one domain can access resources from a server on a different domain. By default, web browsers have a Same-Origin Policy (SOP) that blocks these cross-origin requests for security purposes. However, CORS offers a secure way for servers to specify which origins are allowed to access their assets, thereby enabling a structured method of relaxing this policy.
In CORS, the server sends HTTP headers to instruct the browser on rules for making cross-origin requests. These rules define whether a particular HTTP request (such as GET or POST) from a certain origin is allowed. By managing the CORS headers, a server can control its resource accessibility on a case-by-case basis. This maintains the flexibility of cross-origin sharing without compromising overall security.
Continue readingMyBB is one seriously popular type of open-source forum software. However, even a popular tool can contain bugs or even bug chains that can lead to the compromise of an entire system. In this article, we’ll go over one such chain that we found.
Continue readingTo properly assess the security of a web application, it’s important to analyze it with regard to the server it will run on. Many things depend on the server, from processing user requests to the easiest way of achieving RCE. Armed with knowledge about the server, we can identify vulnerabilities in an application and make it more secure.
In this article we’ll look at Jetty, a well-known web server and Java web container that is typically deployed behind an Apache or NGINX proxy server. Here’s what we’ll cover:
Many modern websites employ an automatic issuance and renewal of TLS certificates. For enterprises, there are DigiCert services. For everyone else, there are free services such as Let’s Encrypt and ZeroSSL.
There is a flaw in a way that deployment of TLS certificates might be set up. It allows anyone to discover all domain names used by the same server. Sometimes, even when there is no HTTPS there!
In this article, I describe a new technique for discovering domain names. Afterward, I show how to use it in threat intelligence, penetration testing, and bug bounty.
Continue readingCross-Site Scripting (XSS) is one of the most commonly encountered attacks in web applications. If an attacker can inject a JavaScript code into the application output, this can lead not only to cookie theft, redirection or phishing, but also in some cases to a complete compromise of the system.
In this article I’ll show how to achieve a Remote Code Execution via XSS on the examples of Evolution CMS, FUDForum, and GitBucket.
Continue readingDuring an internal penetration test, I discovered an unauthenticated Arbitrary Object Instantiation vulnerability in LAM (LDAP Account Manager), a PHP application.
PHP’s Arbitrary Object Instantiation is a flaw in which an attacker can create arbitrary objects. This flaw can come in all shapes and sizes. In my case, the vulnerable code could have been shortened to one simple construction:
new $_GET['a']($_GET['b']);That’s it. There was nothing else there, and I had zero custom classes to give me a code execution or a file upload. In this article, I explain how I was able to get a Remote Code Execution via this construction.
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