CVE-2013-5663 in PAN-OS
Summary
by MITRE
The App-ID cache feature in Palo Alto Networks PAN-OS before 4.0.14, 4.1.x before 4.1.11, and 5.0.x before 5.0.2 allows remote attackers to bypass intended security policies via crafted requests that trigger invalid caching, as demonstrated by incorrect identification of HTTP traffic as SIP traffic, aka Ref ID 47195.
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Analysis
by VulDB Data Team • 10/07/2018
The vulnerability identified as CVE-2013-5663 represents a critical flaw in the application identification caching mechanism of Palo Alto Networks PAN-OS firewall software. This issue affects multiple versions including pre-4.0.14, pre-4.1.11, and pre-5.0.2 releases, demonstrating the persistent nature of application identification challenges in network security appliances. The vulnerability specifically targets the App-ID cache feature which is responsible for maintaining a database of application signatures and their associated traffic characteristics to enforce security policies effectively.
The technical flaw stems from improper handling of cached application identification data where malicious actors can craft specific network requests that exploit the caching mechanism to cause incorrect application classification. When the firewall processes these crafted requests, the cache becomes corrupted or populated with invalid data, leading to misclassification of legitimate HTTP traffic as SIP (Session Initiation Protocol) traffic. This misclassification allows attackers to bypass security policies that are specifically designed to control or monitor SIP traffic, which typically requires different handling due to its signaling nature and potential for abuse in VoIP attacks.
The operational impact of this vulnerability extends beyond simple policy bypass, as it fundamentally undermines the trustworthiness of the firewall's application identification capabilities. Security administrators who rely on accurate application detection for policy enforcement may find their security controls rendered ineffective, potentially allowing malicious traffic to traverse network boundaries undetected. The vulnerability specifically demonstrates how improper cache management can lead to privilege escalation in terms of network access control, as HTTP traffic that should be subject to different security policies is incorrectly treated as SIP traffic, potentially bypassing controls designed to prevent SIP-based attacks or unauthorized VoIP communications.
This vulnerability aligns with CWE-200 (Information Exposure) and CWE-254 (Weaknesses in Application Identification) categories, representing a failure in maintaining accurate application context within network security appliances. The attack pattern corresponds to techniques described in MITRE ATT&CK framework under T1071.004 (Application Layer Protocol: DNS) and T1566 (Phishing) as attackers can leverage this flaw to manipulate traffic classification and potentially deliver malicious content through incorrectly identified application channels. The issue also reflects broader concerns in network security appliance design related to cache validation and the potential for adversarial inputs to corrupt system state information.
Organizations affected by this vulnerability should immediately implement the vendor-provided patches for PAN-OS versions 4.0.14, 4.1.11, and 5.0.2 to restore proper application identification functionality. Network security teams should also conduct thorough audits of their current application identification policies to ensure that no traffic has been incorrectly classified due to cache corruption. Additionally, implementing monitoring for unusual application classification patterns and establishing more robust cache validation mechanisms can help prevent similar issues in the future. The vulnerability highlights the importance of maintaining proper input validation and cache integrity in security appliances, particularly those that rely on dynamic application identification mechanisms for policy enforcement decisions.