CVE-2015-0693 in Web Security Appliance
Summary
by MITRE
Cisco Web Security Appliance (WSA) devices with software 8.5.0-ise-147 do not properly restrict use of the pickle Python module during certain tunnel-status checks, which allows local users to execute arbitrary Python code and gain privileges via a crafted pickle file, aka Bug ID CSCut39259.
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Analysis
by VulDB Data Team • 05/09/2022
The vulnerability identified as CVE-2015-0693 affects Cisco Web Security Appliance devices running software version 8.5.0-ise-147, representing a critical security flaw that undermines the integrity of the system's privilege management mechanisms. This issue stems from improper restrictions on the pickle Python module usage during specific tunnel-status checks, creating an exploitable condition that enables local attackers to execute arbitrary code with elevated privileges. The vulnerability is particularly concerning as it allows attackers who already have local access to escalate their privileges and potentially gain full system control, making it a significant threat vector for both insider attacks and compromised accounts.
The technical flaw manifests in the improper handling of Python pickle module operations within the WSA's tunnel-status checking functionality. The pickle module in Python is designed for serializing and deserializing Python objects, but it is inherently dangerous when used with untrusted data because it can execute arbitrary code during the deserialization process. In this case, the WSA software fails to properly validate or restrict pickle operations during tunnel-status checks, allowing a local attacker to craft a malicious pickle file that, when processed by the system, triggers code execution. This represents a classic example of insecure deserialization vulnerability that can be exploited to bypass normal security controls and privilege boundaries.
The operational impact of this vulnerability extends beyond simple code execution, as it fundamentally compromises the security model of the Cisco Web Security Appliance. Local users who can create or modify files on the system can leverage this flaw to execute arbitrary Python code with the privileges of the affected service account, which typically has elevated system permissions. This privilege escalation capability can lead to complete system compromise, data exfiltration, and potential lateral movement within the network environment where the appliance operates. The vulnerability affects organizations relying on WSA for web security filtering, potentially exposing their network infrastructure to unauthorized access and malicious activities.
Mitigation strategies for CVE-2015-0693 should prioritize immediate software updates to address the vulnerability, as Cisco has released patches specifically designed to fix the insecure pickle module usage in the affected software versions. Organizations should also implement strict file access controls and monitoring to detect unauthorized modifications to system files that might be used to create malicious pickle payloads. Network segmentation and privilege minimization practices should be enforced to limit the potential impact of successful exploitation. From a compliance perspective, this vulnerability aligns with CWE-502 which describes "Deserialization of Untrusted Data" and relates to ATT&CK technique T1059.007 for Python-based execution, making it critical for organizations to address through both immediate patching and broader security posture improvements.