CVE-2007-1742 in HTTP Server
Summary
by MITRE
suexec in Apache HTTP Server (httpd) 2.2.3 uses a partial comparison for verifying whether the current directory is within the document root, which might allow local users to perform unauthorized operations on incorrect directories, as demonstrated using "html_backup" and "htmleditor" under an "html" directory. NOTE: the researcher, who is reliable, claims that the vendor disputes the issue because "the attacks described rely on an insecure server configuration" in which the user "has write access to the document root."
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Analysis
by VulDB Data Team • 07/23/2024
The vulnerability described in CVE-2007-1742 affects the suexec module within Apache HTTP Server version 2.2.3, representing a critical security flaw that undermines the integrity of directory access controls. This issue stems from a flawed comparison mechanism within the suexec functionality that fails to perform a complete verification of directory paths, creating a potential vector for privilege escalation attacks. The vulnerability specifically manifests when the system attempts to validate whether the current working directory resides within the designated document root, where a partial string comparison allows malicious actors to bypass intended access restrictions. The flaw enables local users to execute unauthorized operations on directories that should remain protected, effectively undermining the security boundaries established by the web server configuration. This type of vulnerability directly relates to CWE-254, which encompasses security weaknesses involving improper privilege management and access control mechanisms.
The technical implementation of this vulnerability exploits a fundamental flaw in path validation logic where the suexec module performs a substring comparison rather than a comprehensive path verification process. When processing requests, the system checks if the current directory is within the document root by comparing only a portion of the path, allowing attackers to manipulate directory structures to bypass these security checks. The demonstration case illustrates how directories named "html_backup" and "htmleditor" located under an "html" directory could be accessed through this vulnerability, showing that the partial comparison fails to properly validate the complete directory hierarchy. This approach essentially creates a path traversal condition where attackers can navigate to unintended directories while maintaining the appearance of legitimate access within the document root boundaries. The vulnerability aligns with ATT&CK technique T1068, which involves the use of legitimate credentials and system tools to gain elevated privileges through improper access control mechanisms.
The operational impact of CVE-2007-1742 extends beyond simple unauthorized access, potentially enabling attackers to execute arbitrary code with elevated privileges or gain access to sensitive system resources. Local users who can manipulate directory structures to exploit this partial comparison flaw can effectively bypass the intended security boundaries that protect web server content and system resources. The vulnerability's severity is amplified when considering that it allows for privilege escalation attacks that could compromise the entire web server infrastructure, potentially leading to full system compromise. Security researchers have noted that the vulnerability requires specific conditions to be exploited successfully, including the presence of writable directories within the document root that can be manipulated by local users. The vendor's response dismissing the issue as relying on "insecure server configuration" highlights the complexity of determining vulnerability severity, as the flaw may only be exploitable under specific circumstances where user permissions have been improperly configured.
Mitigation strategies for this vulnerability require both immediate configuration adjustments and long-term architectural improvements to prevent exploitation. System administrators should ensure that document root directories are properly secured with restrictive permissions that prevent unauthorized write access from user accounts, thereby eliminating the attack vector that enables exploitation. The recommended approach involves implementing comprehensive access control policies that enforce strict directory permissions and validate all user access attempts through robust path verification mechanisms. Organizations should also consider implementing additional monitoring and logging of directory access attempts to detect potential exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper input validation and access control implementation in security-critical modules such as suexec, where even seemingly minor implementation flaws can result in significant security breaches. Regular security audits should include verification of path validation mechanisms to ensure that all comparisons are performed using complete string matching rather than partial comparisons that could be exploited by attackers.