F5 is warning of active abuse of a critical security flaw in BIG-IP less than a week after its public disclosure that could result in the execution of arbitrary system commands as part of an exploit chain.

Tracked as CVE-2023-46747 (CVSS score: 9.8), the vulnerability allows an unauthenticated attacker with network access to the BIG-IP system through the management port to achieve code execution. A proof-of-concept (PoC) exploit has since been made available by ProjectDiscovery.

It impacts the following versions of the software -

• 17.1.0 (Fixed in 17.1.0.3 + Hotfix-BIGIP-17.1.0.3.0.75.4-ENG)
• 16.1.0 - 16.1.4 (Fixed in 16.1.4.1 + Hotfix-BIGIP-16.1.4.1.0.50.5-ENG)
• 15.1.0 - 15.1.10 (Fixed in 15.1.10.2 + Hotfix-BIGIP-15.1.10.2.0.44.2-ENG)
• 14.1.0 - 14.1.5 (Fixed in 14.1.5.6 + Hotfix-BIGIP-14.1.5.6.0.10.6-ENG)
• 13.1.0 - 13.1.5 (Fixed in 13.1.5.1 + Hotfix-BIGIP-13.1.5.1.0.20.2-ENG)

Now the company is alerting that it has "observed threat actors using this vulnerability to exploit CVE-2023-46748," which refers to an authenticated SQL injection vulnerability in the BIG-IP Configuration utility.

"This vulnerability may allow an authenticated attacker with network access to the Configuration utility through the BIG-IP management port and/or self IP addresses to execute arbitrary system commands," F5 noted in an advisory for CVE-2023-46748 (CVSS score: 8.8).

In other words, bad actors are chaining the two flaws to run arbitrary system commands. To check for indicators of compromise (IoCs) associated with the SQL injection flaw, users are recommended to check the /var/log/tomcat/catalina.out file for suspicious entries like below -

{...}
 java.sql.SQLException: Column not found: 0.
 {...)
 sh: no job control in this shell
 sh-4.2$ <EXECUTED SHELL COMMAND>
 sh-4.2$ exit.

The Shadowserver Foundation, in a post on X (formerly Twitter), said it has been "seeing F5 BIG-IP CVE-2023-46747 attempts in our honeypot sensors" since October 30, 2023, making it imperative that users move quickly to apply the fixes.