CVE-2015-4198 in Web Security Appliance
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the web framework on Cisco Web Security Appliance (WSA) devices with software 8.5.0-497 allows remote attackers to inject arbitrary web script or HTML via an unspecified HTTP header, aka Bug ID CSCuu24409.
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Analysis
by VulDB Data Team • 05/21/2022
The vulnerability CVE-2015-4198 represents a critical cross-site scripting flaw in Cisco Web Security Appliance devices running software version 8.5.0-497. This security weakness resides within the web framework component of the WSA platform, which serves as a crucial network security device for web content filtering and threat prevention. The vulnerability specifically manifests when the appliance processes HTTP headers from incoming web requests, creating an avenue for malicious actors to execute arbitrary code within the context of a victim's browser session. The issue stems from inadequate input validation and sanitization mechanisms within the web interface, allowing attackers to inject malicious scripts that can persistently execute against users who interact with compromised web content.
The technical exploitation of this vulnerability occurs through manipulation of HTTP headers, which are typically used for communication metadata between web clients and servers. Attackers can craft malicious HTTP requests containing specially formatted script payloads within header fields, bypassing normal security controls that would typically filter or sanitize such content. When the WSA device processes these malformed headers and subsequently displays them in web interfaces or logs, the embedded scripts execute in the browser context of authenticated users. This behavior aligns with CWE-79, which defines cross-site scripting as the improper handling of untrusted data within web applications, and represents a classic server-side injection vulnerability that can lead to session hijacking, credential theft, or arbitrary code execution. The attack vector is particularly concerning because it leverages the appliance's own web interface to deliver malicious content, making it difficult to detect through traditional network monitoring approaches.
The operational impact of CVE-2015-4198 extends beyond simple script injection, as it can compromise the entire security posture of networks relying on Cisco WSA devices for web filtering. An attacker who successfully exploits this vulnerability can potentially escalate privileges, access sensitive administrative interfaces, or redirect users to malicious websites that appear to be legitimate corporate resources. The vulnerability affects organizations that depend on web security appliances for protection against external threats, potentially undermining the very security controls designed to protect against such attacks. Network defenders face the challenge of detecting exploitation attempts that occur within the appliance's own web interface, as these attacks can appear as legitimate traffic patterns to standard intrusion detection systems. The risk is further amplified by the fact that the WSA device often operates as a central point of control for web traffic within enterprise environments, making successful exploitation potentially devastating to overall network security.
Organizations should implement immediate mitigations including applying Cisco's security patches and updates as released through their official advisory channels, which would address the specific input validation issues within the web framework. Network segmentation and monitoring should be enhanced to detect unusual HTTP header patterns that may indicate exploitation attempts, while implementing proper web application firewalls to filter malicious content at the network perimeter. Security teams should also conduct comprehensive vulnerability assessments of all WSA devices in their environment to identify affected systems and ensure proper patch management protocols are in place. The vulnerability's classification under ATT&CK technique T1566.001 for "Phishing with Malicious Content" highlights the importance of defensive measures against social engineering attacks that leverage such technical vulnerabilities. Additionally, implementing robust input sanitization policies and regular security audits of web applications can help prevent similar issues from arising in other components of the security infrastructure.