CVE-2016-5410 in firewalld
Summary
by MITRE
firewalld.py in firewalld before 0.4.3.3 allows local users to bypass authentication and modify firewall configurations via the (1) addPassthrough, (2) removePassthrough, (3) addEntry, (4) removeEntry, or (5) setEntries D-Bus API method.
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Analysis
by VulDB Data Team • 09/26/2024
The vulnerability identified as CVE-2016-5410 affects firewalld versions prior to 0.4.3.3 and represents a critical authentication bypass flaw within the D-Bus interface of the firewall management system. This issue resides in the firewalld.py script which serves as the primary interface for configuring firewall rules through the D-Bus messaging system. The vulnerability stems from insufficient input validation and authentication checks within five specific D-Bus API methods that handle passthrough and entry management operations.
The technical flaw manifests through the absence of proper authentication verification when processing D-Bus method calls for adding or removing passthrough rules and entries within the firewall configuration. Attackers can exploit this weakness by directly invoking the affected D-Bus methods without proper authorization, effectively allowing any local user to modify critical network security policies. This represents a classic privilege escalation vulnerability where the system fails to validate the identity or permissions of callers attempting to modify firewall configurations through the D-Bus interface.
From an operational impact perspective, this vulnerability enables local users to gain unauthorized access to network security controls, potentially allowing them to open ports, modify rule sets, or disable firewall protections entirely. The implications extend beyond simple privilege escalation as compromised local accounts could lead to complete network exposure or facilitate further attacks. According to CWE-284, this vulnerability maps directly to inadequate access control mechanisms where the system fails to properly enforce authorization checks for critical system functions. The attack vector aligns with ATT&CK technique T1068 which describes local privilege escalation through exploitation of system vulnerabilities.
The security implications of this vulnerability are particularly severe given that firewalld serves as a core network security component in many Linux distributions. An attacker who gains local access to a system running an affected firewalld version could immediately compromise network security policies without requiring additional credentials or elevated privileges. The vulnerability affects the integrity and availability of network security controls, potentially allowing malicious actors to create backdoors or disable protective measures. Organizations implementing firewalld for network protection face significant risk exposure, as this vulnerability essentially removes the authentication layer protecting critical firewall configuration changes.
Mitigation strategies should prioritize immediate patching of firewalld to version 0.4.3.3 or later, which addresses the authentication bypass by implementing proper D-Bus method authorization checks. System administrators should also consider implementing additional monitoring of D-Bus traffic for unusual patterns of firewall configuration changes, particularly focusing on the affected API methods. Network segmentation and least privilege principles should be enforced to limit local user access to systems running firewalld, while regular security audits should verify that firewall configurations remain intact and properly enforced. The remediation process should include verification that all affected systems have been updated and that no unauthorized firewall modifications occurred during the vulnerability window.