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February 6, 2025
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How To Fix CVE-2025-20029: Command Injection Vulnerability in F5 BIG-IP TMOS Shell Exploiting System Commands?
F5 BIG-IP is a widely used application delivery controller (ADC) that provides traffic management, security, and optimization features. A recently disclosed command injection vulnerability, CVE-2025-20029, poses a significant threat to organizations utilizing affected versions of BIG-IP. This vulnerability allows an authenticated attacker with low privileges to execute arbitrary system commands, potentially leading to full system compromise. This article provides a detailed overview of CVE-2025-20029, including its impact, affected products, and practical steps security professionals can take to mitigate and remediate the vulnerability. Targeted at security professionals in DevSecOps, application security, and related fields, this guide aims to provide actionable information to safeguard F5 BIG-IP deployments.
A Short Introduction to F5 BIG-IP
F5 BIG-IP is a suite of application delivery and security products that manage network traffic and improve application performance. It combines hardware and software to provide features such as load balancing, application security, and access control. Key components of BIG-IP include:
LTM (Local Traffic Manager): Manages and optimizes application traffic within a data center.
APM (Access Policy Manager): Controls user access to applications with features like authentication and authorization.
ASM (Application Security Manager): Protects applications from web-based attacks with a web application firewall (WAF).
AFM (Advanced Firewall Manager): Provides network firewall capabilities to secure the infrastructure.
BIG-IP is crucial for organizations that require high availability, scalability, and security for their applications. Its widespread use makes it a critical target for attackers, highlighting the importance of addressing vulnerabilities like CVE-2025-20029.
Summary of CVE-2025-20029
CVE ID: CVE-2025-20029
Description: Command injection vulnerability in iControl REST and BIG-IP TMOS Shell (tmsh) save command that allows an authenticated attacker with low privileges to execute arbitrary system commands.
CVSS Score: 8.7 (High)
CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CVE-2025-20029 is a command injection vulnerability found in the iControl REST API and the BIG-IP TMOS Shell (tmsh) when using the save command. This flaw allows an authenticated attacker with low privileges to inject and execute arbitrary system commands. The vulnerability arises due to insufficient sanitization of input provided to the save command, which, when processed by the system, allows the execution of malicious code.
An attacker can exploit this vulnerability by sending a crafted request either through the iControl REST API or by executing a specially crafted tmsh save command. Successful exploitation grants the attacker the ability to execute commands with elevated privileges, potentially compromising the entire system. This type of vulnerability is especially dangerous as it bypasses typical security controls by leveraging legitimate system functionalities in unintended ways.
Given the high CVSS score and the potential for complete system compromise, it is crucial for organizations using affected BIG-IP versions to address this vulnerability immediately.
Impact of CVE-2025-20029
The impact of CVE-2025-20029 is significant due to the potential for arbitrary command execution. An attacker who successfully exploits this vulnerability can gain unauthorized access to sensitive data, modify system configurations, and disrupt critical services. This can lead to:
Confidentiality Breach: Sensitive data, such as user credentials, configuration files, and customer information, can be accessed and exfiltrated.
Integrity Compromise: System configurations can be altered, leading to instability, misconfiguration, or the introduction of malicious functionality.
Availability Disruption: Critical services can be disrupted or rendered unavailable, leading to business interruption and financial loss.
With a CVSS v3.1 base score of 8.8 and a CVSS v4.0 base score of 8.7, both rated as HIGH, the vulnerability underscores the serious risk it poses to organizations relying on F5 BIG-IP for application delivery and security. The ability to execute arbitrary system commands provides a pathway for attackers to establish persistence, escalate privileges, and launch further attacks on the network, making swift remediation essential. You can also read what is a vulnerability to learn more.
Products Affected by CVE-2025-20029
The following BIG-IP versions are affected by CVE-2025-20029:
|
Product
|
Branch
|
Versions Known to be Vulnerable
|
Fixes Introduced In
|
|---|---|---|---|
|
BIG-IP (all modules)
|
17.x
|
17.1.0 - 17.1.2
|
|
|
BIG-IP (all modules)
|
16.x
|
16.1.0 - 16.1.5
|
|
|
BIG-IP (all modules)
|
15.x
|
15.1.0 - 15.1.10
|
|
|
BIG-IP Next (all modules)
|
All
|
None
|
Not applicable
|
|
BIG-IP Next Central Manager
|
All
|
None
|
Not applicable
|
|
BIG-IP Next SPK
|
All
|
None
|
Not applicable
|
|
BIG-IP Next CNF
|
All
|
None
|
Not applicable
|
|
BIG-IQ Centralized Management
|
All
|
None
|
Not applicable
|
|
F5OS-A
|
All
|
None
|
Not applicable
|
|
F5OS-C
|
All
|
None
|
Not applicable
|
|
NGINX (all products)
|
All
|
None
|
Not applicable
|
|
Traffix SDC
|
All
|
None
|
Not applicable
|
Important Notes:
F5 evaluates only software versions that have not yet reached the End of Technical Support (EoTS) phase of their lifecycle.
BIG-IQ Centralized Management, F5OS, NGINX, and Traffix SDC are not affected by this vulnerability.
How to Check Your Product is Vulnerable?
To determine if your F5 BIG-IP installation is vulnerable to CVE-2025-20029, follow these steps:
1. Check the BIG-IP Version:
Log into the BIG-IP Configuration utility.
Navigate to System > Platform.
Note the version number displayed.
Compare the version number to the list of vulnerable versions provided in the "Products Affected by CVE-2025-20029" section.
2. Verify the Affected Components:
Confirm that you are using the iControl REST API or the TMOS Shell (tmsh) with the
savecommand.If these components are in use and the version is within the vulnerable range, your system is likely susceptible.
3. Monitor System Logs:
Examine system logs for any unusual activity related to the iControl REST API or TMOS Shell, particularly around the save command.
Look for unexpected command executions or attempts to access sensitive files or directories.
4. Run Vulnerability Scans:
Utilize vulnerability scanners that include checks for CVE-2025-20029. Ensure the scanner is up-to-date with the latest vulnerability definitions.
Review the scan results for any findings related to this vulnerability. Also check the vulnerability assessments strategy for identifying and prioritizing system risks.
How to Fix CVE-2025-20029?
To remediate CVE-2025-20029, follow these steps:
1. Apply the Patch:
Upgrade your F5 BIG-IP system to a fixed version. Refer to the "Products Affected by CVE-2025-20029" section for the appropriate fixed version for your branch.
Download the software update from the F5 Downloads site.
Follow the F5 upgrade guide to install the update.
2. Mitigation Strategies (If Patching Is Not Immediately Possible):
Restrict Access to iControl REST:
* Limit access to the iControl REST interface to only trusted networks or devices.
* Change the Port Lockdown setting to Allow None for each self IP address in the system. If you must open any ports, use the Allow Custom option, taking care to disallow access to iControl REST.
* Block iControl REST access through the management interface by restricting management access only to trusted users and devices over a secure network.
Restrict Access to the BIG-IP command line through SSH:
* Block SSH access through self IP addresses by changing the Port Lockdown setting to Allow None for each self IP address on the system. If you must open any ports, use the Allow Custom option, taking care to block access to SSH.
* Restrict management access to F5 products to only trusted users and devices over a secure network.
Monitor Activity:
* Monitor and audit all activities related to iControl REST and BIG-IP TMOS Shell, especially the save command.
* Implement network segmentation to limit the potential impact if the vulnerability is exploited.
* Regularly review and update authentication mechanisms to ensure they are as robust as possible. You can read what is authentication bypass for more information.
Important Considerations:
Before making changes to the configuration of your self IP addresses, refer to F5's documentation on port lockdown behavior and securing access to the BIG-IP system.
Ensure that you have a backup of your BIG-IP configuration before applying any updates or mitigations.
Monitor F5's security advisories for any new information or guidance related to this vulnerability.
As this attack is conducted by legitimate, authenticated users, there is no viable mitigation that also allows users access to the BIG-IP system. The only mitigation is to remove access for users who are not completely trusted. You can implement zero trust security to enhance the security.
By following these steps, security professionals can effectively address CVE-2025-20029 and protect their F5 BIG-IP deployments from potential exploitation.
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Arun KL
Arun KL is a cybersecurity professional with 15+ years of experience in IT infrastructure, cloud security, vulnerability management, Penetration Testing, security operations, and incident response. He is adept at designing and implementing robust security solutions to safeguard systems and data. Arun holds multiple industry certifications including CCNA, CCNA Security, RHCE, CEH, and AWS Security.
