Security Experts:

Researchers Raise Alarm for F5 BIG-IP Malware Attacks

The urgency to patch gaping security holes in F5 Networks BIG-IP and BIG-IQ products escalated over the weekend after researchers spotted malicious in-the-wild attack activity.

Malware hunters at U.K.-based NCC Group are raising the alarm for mass scanning and “multiple exploitation attempts” with exploits targeting critical security flaws in the F5 enterprise networking infrastructure products.

The vulnerabilities were patched on March 10 and are considered high-priority fixes because of the risk of exposure to authentication bypass and remote code execution attacks.

Less than a week after the release of the patches, proof-of-concept code started circulating and, over the last weekend, NCC Group’s researchers said its honeypot infrastructure was being hit with exploitation attempts.

[SEE: BIG-IP Vulnerability Exploited to Deliver DDoS Malware ]

“This knowledge, combined with having reproduced the full exploit-chain we assess that a public exploit is likely to be available in the public domain soon,” NCC Group warned.

The researchers explain the exploitation path:

Exploitation of this vulnerability requires two steps. First, authentication has to be bypassed by leveraging the SSRF vulnerability to gain an authenticated session token. This authenticated session can then be used to interact with REST API endpoints, which would otherwise require authentication.


The most useful endpoint for an attacker is the tm/util/bash endpoint, which allows an (authenticated) user to execute commands on the underlying server with root privileges. However, as the REST API is designed for remote administration, there are many endpoints which an attacker might wish to take advantage of.


As part of the F5 patches, a command injection vulnerability was also patched in the tm/access/bundle-install-tasks REST endpoint – which could be used as an alternative way to execute arbitrary commands once authentication has been bypassed.

NCC Group also released Suricata network rules to help defenders mitigate this threat.

The U.S. government’s CISA (Cybersecurity and Infrastructure Security Agency (CISA) also released an advisory to underline the importance of reviewing F5’s advisory and applying the updates.

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Ryan Naraine is Editor-at-Large at SecurityWeek and host of the popular Security Conversations podcast series. He is a journalist and cybersecurity strategist with more than 20 years experience covering IT security and technology trends. Ryan has built security engagement programs at major global brands, including Intel Corp., Bishop Fox and Kaspersky GReAT. He is a co-founder of Threatpost and the global SAS conference series. Ryan's career as a journalist includes bylines at major technology publications including Ziff Davis eWEEK, CBS Interactive's ZDNet, PCMag and PC World. Ryan is a director of the Security Tinkerers non-profit, and a regular speaker at security conferences around the world. Follow Ryan on Twitter @ryanaraine.