F5 BIG-IP Flaw Let Hackers Execute Arbitrary System Commands

F5 Networks have addressed critical vulnerabilities in its BIG-IP networking device. The vulnerability tracked as CVE-2021-23031 is a privilege escalation issue on BIG-IP Advanced Web Application Firewall (WAF) and Application Security Manager (ASM) Traffic Management User Interface (TMUI).

BIG-IP Flaw

According to the security advisory, when this vulnerability is exploited, an authenticated attacker with access to the Configuration utility can execute arbitrary system commands, create or delete files, and/or disable services.

Similarly, this flaw may result in complete system compromise. BIG-IP systems have the option of running in Appliance mode.

This appliance mode is designed to meet the needs of customers in, particularly sensitive sectors by limiting the BIG-IP system administrative access to match that of a typical network appliance and not a multi-user UNIX device.

The flaw has a severity score of 8.8, nevertheless, the security advisory says, for customers using the Appliance Mode, applies some technical restrictions, the severity score raises to 9.9 out of 10.

Also, only a limited number of customers are impacted by the issue in a critical mode.

“The limited number of customers using Appliance mode have Scope: Changed, which raises the CVSSv3 score to 9.9”, reads the security advisory.

Product	Branch	Versions known to be vulnerable1	Fixes introduced in	Severity	CVSSv3 score2	Vulnerable component or feature
BIG-IP (Advanced WAF and ASM)	16.x	16.0.0 – 16.0.1	16.1.0 16.0.1.2	High — Critical – Appliance mode only3	8.8 — 9.93	TMUI/Configuration utility
15.x	15.1.0 – 15.1.2	15.1.3
14.x	14.1.0 – 14.1.4	14.1.4.1
13.x	13.1.0 – 13.1.3	13.1.4
12.x	12.1.0 – 12.1.5	12.1.6
11.x	11.6.1 – 11.6.5	11.6.5.3
BIG-IP (all other modules)	16.x	None	Not applicable	Not vulnerable	None	None
15.x	None	Not applicable
14.x	None	Not applicable
13.x	None	Not applicable
12.x	None	Not applicable
11.x	None	Not applicable
BIG-IQ Centralized Management	8.x	None	Not applicable	Not vulnerable4	None	None
7.x	None	Not applicable
6.x	None	Not applicable
F5OS	1.x	None	Not applicable	Not vulnerable	None	None
Traffix SDC	5.x	None	Not applicable	Not vulnerable	None	None

 List of Issues Addressed by F5

F5 mentions that users can eliminate this vulnerability by installing a version listed in the Fixes column.

F5 addressed 30 high-severity vulnerabilities in multiple products, which include authenticated remote command execution flaws, cross-site scripting (XSS) issues, request forgery issues, insufficient permission, and denial-of-service flaws.

Mitigation

F5 states that the only mitigation is to remove access for users who are not completely trusted since this attack is conducted by legitimate and authenticated users.

• Block Configuration utility access through self IP addresses.
• Block Configuration utility access through the management interface These mitigations restrict access to the Configuration utility to only trusted networks or devices, thereby limiting the attack surface.