Contact Sales

GoSecure Blog

Beyond XSS: Edge Side Include Injection

Update: A new blog post has been published as a follow up to this article : ESI Part 2: Abusing specific implementations.

Abusing Caching Servers into SSRF and Client-Side Attacks

While conducting a security assessment, we noticed an unexpected behavior in the markup language Edge Side Includes (ESI), a language used in many popular HTTP surrogates (reverse proxies, load balancers, caching servers, proxy servers). We identified that successful ESI attacks can lead to Server Side Request Forgery (SSRF), various Cross-Site Scripting (XSS) vectors that bypass the HTTPOnly cookie mitigation flag, and server-side denial of service. We call this technique ESI Injection.

Read More

Topics: appsec, SSRF, vulnerability, web, XSS, ESI, exploitation, Featured

Detecting deserialization bugs with DNS exfiltration

At the moment, Java deserialization vulnerabilities are becoming well known by vendors and attackers. Nevertheless, pentesters will still encounter these types of vulnerabilities. The low-hanging fruits can be identified with the current tools. Most of the available tools rely on the command execution API. However, the command from the payload may fail because of Operating System specific conditions. Additionally, the command used might be missing or the arguments it requires may differ due to the version of the command or the flavor installed (ie: GNU netcat vs OpenBSD netcat for example).

Read More

Topics: deserialization, detection, vulnerability, web, weblogic, dns, exploit, java, jboss, jenkins

Binary Webshell Through OPcache in PHP 7

In this article, we will be looking at a new exploitation technique using the default OPcache engine from PHP 7.  Using this attack vector, we can bypass certain hardening techniques that disallow the file write access in the web directory. This could be used by an attacker to execute his own malicious code in a hardened environment.

Read More

Topics: web, exploitation, opcache, php, php7, Featured