CVE-2020-5873 in BIG-IP
Summary
by MITRE
On BIG-IP 15.0.0-15.0.1, 14.1.0-14.1.2.3, 13.1.0-13.1.3.1, 12.1.0-12.1.5, and 11.6.1-11.6.5 and BIG-IQ 5.2.0-7.1.0, a user associated with the Resource Administrator role who has access to the secure copy (scp) utility but does not have access to Advanced Shell (bash) can execute arbitrary commands using a maliciously crafted scp request.
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Analysis
by VulDB Data Team • 05/01/2020
The vulnerability identified as CVE-2020-5873 represents a critical privilege escalation flaw within F5 Networks BIG-IP and BIG-IQ platforms that affects multiple version ranges across different product lines. This security weakness specifically targets systems where users possess the Resource Administrator role but lack direct access to the Advanced Shell interface. The vulnerability stems from insufficient input validation and access control mechanisms within the secure copy utility implementation, creating an exploitable condition that allows maliciously crafted scp requests to bypass intended security restrictions. The flaw exists in the way the system processes scp commands, particularly when handling user-provided parameters that should normally be restricted or validated before execution. This issue directly violates the principle of least privilege and demonstrates a significant gap in the access control model implemented by the F5 platform.
The technical exploitation of this vulnerability occurs through the manipulation of scp request parameters that are processed by the underlying system without proper sanitization or authorization checks. When a Resource Administrator with scp access attempts to execute a maliciously crafted scp command, the system fails to properly validate the input, allowing arbitrary command execution to occur through the scp utility. This creates a pathway for attackers to bypass the intended security boundaries that separate different user roles and access levels. The vulnerability operates at the command execution layer where scp requests are translated into system commands, and the lack of proper input validation allows attackers to inject additional commands that would normally be restricted to users with higher privileges. This type of flaw is categorized under CWE-78 as "Improper Neutralization of Special Elements used in an OS Command" and aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter.
The operational impact of CVE-2020-5873 is severe as it provides attackers with a means to escalate privileges from a limited Resource Administrator role to potentially full system access without requiring additional authentication or elevated privileges. An attacker who has already gained access to a system with Resource Administrator privileges can leverage this vulnerability to execute arbitrary commands with the same privileges as the system itself, effectively bypassing the intended security controls. This vulnerability can be exploited to gain access to sensitive system information, modify configurations, install malware, or establish persistent access points within the network infrastructure. The widespread affected versions across multiple BIG-IP and BIG-IQ releases means that organizations with legacy systems are particularly vulnerable, as the flaw exists across several major product versions that may not have been updated regularly. The implications extend beyond simple command execution, as this vulnerability can be used as a stepping stone for further attacks within the network environment.
Organizations should immediately implement mitigations including applying the official F5 security patches released to address this vulnerability, which typically involve updating the affected software versions to those containing the necessary security fixes. Network segmentation and access control measures should be enhanced to limit the scope of potential exploitation, particularly restricting scp access to only trusted users and systems. Monitoring should be implemented to detect suspicious scp activities and unusual command execution patterns that may indicate exploitation attempts. Security teams should conduct comprehensive vulnerability assessments to identify all systems running affected versions of BIG-IP or BIG-IQ software and prioritize remediation efforts accordingly. Additionally, implementing proper role-based access controls and regularly reviewing user permissions can help reduce the attack surface for this type of privilege escalation. The vulnerability demonstrates the importance of maintaining up-to-date security patches and proper access control enforcement within critical infrastructure systems, as it represents a fundamental flaw in the security architecture that can be exploited by attackers with relatively limited initial access privileges.