CVE-2023-21839

In early 2023 a vulnerability was found in the Oracle WebLogic IIOP/T3 protocol. When the IIOP/T3 protocol is enabled, unauthenticated attackers are able to execute arbitrary commands on the system. The vulnerability’s sink point was the following class weblogic.deployment.jms.ForeignOpaqueReference.class which contains a function getReferent which calls the following code:

try {
	var5 = var4.lookup(this.remoteJNDIName);
}

This allows the attacker to initiate a JNDI injection attack by hosting malicious code on their own JNDI server to be downloaded and run by WebLogic. However, due to mitigations put in place by Java this JNDI injection technique used by the exploit is only exploitable on WebLogic Server running older versions of Java.

In the last few years Oracle has applied several restrictions that aimed to prevent attackers from exploiting JNDI Injection vulnerabilities. One example of such restriction is the trustURLCodebase property which was introduced in Java Development Kit 8 – Update 121. This property prevents vulnerable applications from loading malicious objects from remote RMI repositories. Later, a similar restriction was added also to cover LDAP repositories.

Since those restrictions were added, exploiting JNDI Injection vulnerabilities now depends on existing gadgets, which means the classes used in the exploit must reside in the vulnerable application class path for the exploit to work.

CVE-2024-20931

In the January 2024 patch released by Oracle, a remote command execution vulnerability CVE-2024-20931 based on the Weblogic T3\IIOP protocol was fixed. This vulnerability still exploits the getReferent function inside weblogic.deployment.jms.ForeignOpaqueReference.class but it bypasses the patch put in place by CVE-2023-21839. It does this by setting the malicious JNDI url to the environment variable java.naming.provider.url:

String providerURL = (String) this.jndiEnvironment.get("java.naming.provider.url");

which gets initialized after getReferent is called and allows for this JNDI injection to be exploited in an alternate manner.

Caveats

This vulnerability has the same Java version limitations of its predecessor. In order for the WebLogic Server to be vulnerable it must be running Java <= 1.8.0_151. Given that this version of java is over six years old, the attacker value of this unauthenticated RCE vulnerability is quite low.

References

https://glassyamadeus.github.io/2024/01/31/CVE_2024_20931/
https://github.com/dinosn/CVE-2024-20931