CVE-2007-6511 in Enterpise
Summary
by MITRE
Websense Enterprise 6.3.1 allows remote attackers to bypass content filtering by visiting http URLs with a (1) RealPlayer G2, (2) MSMSGS, or (3) StoneHttpAgent User-Agent header, which results in a Non-HTTP categorization.
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Analysis
by VulDB Data Team • 09/13/2018
The vulnerability identified as CVE-2007-6511 affects Websense Enterprise 6.3.1 content filtering software, representing a significant security flaw that enables remote attackers to circumvent organizational web content policies. This issue stems from the software's insufficient handling of specific User-Agent headers that are commonly associated with legitimate media players and client applications. The vulnerability operates by exploiting a gap in the content categorization logic where certain non-standard HTTP requests are not properly evaluated against the organization's filtering rules. When a user accesses a website using one of the three specific User-Agent headers - RealPlayer G2, MSMSGS, or StoneHttpAgent - the system incorrectly classifies these requests as non-HTTP traffic and bypasses the normal content filtering processes. This misclassification occurs because the filtering system fails to properly validate or normalize the User-Agent strings before determining how to process the request.
The technical implementation of this vulnerability demonstrates a fundamental flaw in input validation and traffic classification mechanisms within the Websense Enterprise software. The system's inability to properly parse and categorize requests based on these specific User-Agent headers creates an attack surface that malicious actors can exploit to gain unauthorized access to restricted web content. This vulnerability directly relates to CWE-20, which describes improper input validation, and CWE-284, which addresses inadequate access control mechanisms. The flaw essentially allows attackers to manipulate the content filtering system's behavior by simply modifying the User-Agent string in their HTTP requests, effectively turning the filtering system into a passive observer rather than an active enforcement mechanism. From an operational perspective, this vulnerability undermines the core security posture of organizations relying on Websense Enterprise for web content control, potentially allowing access to malicious websites, inappropriate content, or restricted corporate resources that should be blocked by the filtering policy.
The operational impact of CVE-2007-6511 extends beyond simple content bypassing, as it represents a complete breakdown in the security controls that organizations depend upon for network protection. Organizations utilizing Websense Enterprise 6.3.1 may unknowingly allow their users to access harmful content, download malware, or engage in unauthorized activities while the system appears to be functioning normally. This vulnerability particularly affects enterprises with strict web usage policies, as it provides a simple method for bypassing restrictions on social media, gambling sites, or other potentially harmful categories of content. The attack vector is straightforward and requires minimal technical expertise, making it particularly dangerous in environments where users may not be security-aware. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1071.004 (Application Layer Protocol: DNS) and T1566 (Phishing) as attackers can exploit this weakness to deliver malicious content or bypass security controls that would normally prevent such access. The vulnerability also maps to T1068 (Exploitation for Privilege Escalation) and T1562.001 (Impair Defenses: Disable or Modify Tools) as it effectively disables the content filtering system's ability to properly enforce security policies. Organizations experiencing this vulnerability may see increased security incidents, compliance violations, and potential data breaches resulting from unauthorized web access that bypasses established security controls.
Mitigation strategies for CVE-2007-6511 should focus on immediate software updates and configuration changes to address the root cause of the vulnerability. Organizations should prioritize upgrading to a patched version of Websense Enterprise that properly validates User-Agent headers and implements more robust traffic classification mechanisms. In the interim, network administrators can implement additional filtering rules that specifically block requests containing these problematic User-Agent strings or configure the system to normalize and validate all incoming User-Agent headers before processing. The implementation of network-based controls such as deep packet inspection or additional proxy layers may provide temporary protection while permanent fixes are deployed. Security teams should also consider implementing monitoring solutions that can detect unusual patterns of traffic that might indicate exploitation attempts, including monitoring for requests that contain these specific User-Agent headers. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other content filtering systems and network security controls. Organizations should also review their overall web security policies to ensure that multiple layers of protection are in place, as this vulnerability demonstrates how a single flaw in one component can undermine an entire security architecture. The remediation process should include comprehensive testing to ensure that the fixes do not introduce new issues or disrupt legitimate business operations while effectively addressing the bypass capability that attackers exploited.