CVE-2015-0689 in Cloud Web Security
Summary
by MITRE
Cisco Cloud Web Security before 3.0.1.7 allows remote attackers to bypass intended filtering protection mechanisms by leveraging improper handling of HTTP methods, aka Bug ID CSCut69743.
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Analysis
by VulDB Data Team • 11/17/2019
Cisco Cloud Web Security represents a critical web filtering solution designed to protect enterprise networks from malicious web content and enforce security policies across organizational boundaries. The vulnerability identified as CVE-2015-0689 specifically targets the HTTP method handling mechanisms within the software's filtering engine. This flaw stems from improper validation and processing of HTTP methods, allowing malicious actors to craft requests that bypass the intended security controls. The vulnerability affects versions prior to 3.0.1.7, indicating a specific regression or implementation flaw in the software's request parsing logic that was subsequently addressed in the patched release.
The technical exploitation of this vulnerability occurs through manipulation of HTTP methods during web requests. When the system processes incoming HTTP requests, it fails to properly validate or sanitize the method types being used, creating a pathway for attackers to bypass content filtering restrictions. This improper handling allows attackers to leverage specific HTTP methods that should be blocked or restricted, enabling them to access filtered content or perform actions that would normally be prohibited by the security policies. The vulnerability specifically relates to how the system interprets and processes different HTTP methods such as GET, POST, PUT, DELETE, and others that may be used in malicious request construction.
The operational impact of this vulnerability is significant for organizations relying on Cisco Cloud Web Security for network protection. Attackers can exploit this weakness to access restricted websites, download malicious content, or bypass security controls designed to prevent unauthorized access to sensitive resources. This creates a substantial risk for enterprises as it undermines the fundamental purpose of the web filtering solution, potentially allowing malware distribution, data exfiltration, and other malicious activities to proceed undetected. The bypass capability affects the integrity of the security policy enforcement mechanisms, creating a persistent threat vector that could remain active until the system is properly updated.
Organizations should implement immediate mitigation strategies including updating to Cisco Cloud Web Security version 3.0.1.7 or later, which contains the necessary patches to address the HTTP method handling flaw. Network administrators should also consider implementing additional monitoring and logging controls to detect anomalous HTTP request patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-20, which describes improper input validation, and represents a classic example of how inadequate request parsing can create security bypass opportunities. From an ATT&CK framework perspective, this vulnerability maps to techniques involving command and control communications and persistence mechanisms, as attackers could leverage the bypass to maintain access to filtered resources. Organizations should also review their overall web security posture and consider implementing additional layers of protection such as web application firewalls and enhanced network monitoring to detect and prevent exploitation attempts.