F-Secure identifies serious security issues in F5’s BIG-IP load balancers

Cyber security provider F-Secure is advising organizations using F5 Networks’ BIG-IP load balancer, which is popular amongst governments, banks, and other large corporations, to address security issues in some common configurations of the product.

Adversaries can exploit these insecurely configured load balancers to penetrate networks and perform a wide variety of attacks against organizations, or individuals using web services managed by a compromised device.

The security issue is present in the Tcl programming language that BIG-IP’s iRules (the feature that BIG-IP uses to direct incoming web traffic) are written in. Certain coding practices allow attackers to inject arbitrary Tcl commands which could be executed in the security context of the target Tcl script.

In some cases, exploiting a vulnerable system can be as simple as submitting a command or piece of code as part of a web request, that the technology will execute for the attacker. To make matters worse, there are cases where the compromised device will not record the adversaries’ actions, meaning there would be no evidence that an attack took place. In other cases, an attacker could delete logs that contain evidence of their post-exploit activities – severely hindering any incident investigations.

“This configuration issue is really quite severe because it’s stealthy enough for an attacker to get in, achieve a wide variety of objectives, and then cover their tracks. Plus, many organizations aren’t prepared to find or fix issues that are buried deep in software supply chains, which adds up to a potentially big security problem,” explains F-Secure Senior Security Consultant Christoffer Jerkeby. “Unless you know what to look for, it’s tough to foresee this problem occurring, and even harder to deal with in an actual attack.”

F-Secure has helped develop some free, open-source tools that organizations can use to identify insecure configurations in their BIG-IP implementations.

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