CVE-2016-5020 in BIG-IP
Summary
by MITRE
F5 BIG-IP before 12.0.0 HF3 allows remote authenticated users to modify the account configuration of users with the Resource Administration role and gain privilege via a crafted external Extended Application Verification (EAV) monitor script.
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Analysis
by VulDB Data Team • 01/29/2019
The vulnerability identified as CVE-2016-5020 affects F5 BIG-IP systems running versions prior to 12.0.0 HF3, representing a critical privilege escalation flaw within the application delivery controller infrastructure. This vulnerability specifically targets systems that utilize the Resource Administration role, which grants users certain administrative capabilities within the BIG-IP environment. The flaw manifests through a crafted external Extended Application Verification (EAV) monitor script that allows authenticated users to manipulate account configurations, effectively enabling them to escalate their privileges beyond their original authorization levels.
The technical implementation of this vulnerability stems from insufficient input validation and access control mechanisms within the EAV monitor functionality. When users with the Resource Administration role execute or modify EAV monitor scripts, the system fails to properly validate the integrity and authorization of these external scripts. This weakness creates an opportunity for malicious actors to craft scripts that can manipulate user account configurations, potentially allowing them to elevate their privileges or gain unauthorized access to additional administrative functions. The vulnerability operates at the application layer and requires authentication, making it exploitable by users who already possess some level of access to the system.
The operational impact of CVE-2016-5020 is significant for organizations relying on F5 BIG-IP appliances for their network infrastructure. Successful exploitation could enable attackers to gain elevated privileges within the BIG-IP management interface, potentially leading to complete compromise of the application delivery controller. This vulnerability particularly affects organizations that utilize the Resource Administration role for their operational workflows, as it directly undermines the principle of least privilege that should govern access controls within critical infrastructure systems. The ability to modify account configurations also opens pathways for persistent access and further lateral movement within the network environment.
Organizations should immediately implement the vendor-provided security patches for F5 BIG-IP version 12.0.0 HF3 or later to remediate this vulnerability. Additionally, network administrators should conduct thorough audits of user accounts with Resource Administration roles to ensure proper access controls are in place. The mitigation strategy should include implementing strict monitoring of EAV monitor script execution and access patterns, as well as reviewing and limiting the number of users with Resource Administration privileges. This vulnerability aligns with CWE-284, which addresses improper access control in software systems, and represents a clear violation of the principle of least privilege that is fundamental to secure system design. Organizations should also consider implementing the ATT&CK framework's privilege escalation techniques to better understand and defend against similar vulnerabilities in their infrastructure.