CVE-2007-0357 in Fritz!DSL
Summary
by MITRE
Directory traversal vulnerability in the AVM IGD CTRL Service in Fritz!DSL 02.02.29 allows remote attackers to read arbitrary files via ..%5C (URL-encoded dot dot backslash) sequences in a URI requested from the AR7 webserver.
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Analysis
by VulDB Data Team • 09/30/2017
The vulnerability identified as CVE-2007-0357 represents a critical directory traversal flaw within the AVM IGD CTRL Service component of Fritz!DSL firmware version 02.02.29. This security weakness resides in the AR7 webserver implementation that handles HTTP requests, specifically failing to properly validate and sanitize URI paths containing directory traversal sequences. The flaw manifests when the webserver processes requests containing URL-encoded sequences such as ..%5C which translates to ../ in standard notation, allowing attackers to navigate outside the intended directory structure and access arbitrary files on the system.
The technical exploitation of this vulnerability leverages the webserver's insufficient input validation mechanisms that fail to properly interpret and filter malicious URI sequences. When the AR7 webserver receives a request containing the ..%5C pattern, it does not adequately sanitize the path components, enabling an attacker to traverse the file system hierarchy and potentially access sensitive system files, configuration data, or other restricted resources. This weakness directly maps to CWE-22, which defines improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The vulnerability demonstrates a fundamental failure in input validation and access control implementation within the webserver component.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides remote attackers with unauthorized access to potentially sensitive system resources. An attacker could exploit this weakness to read system configuration files, user credentials, or other confidential data stored within the device's file system. The remote nature of the attack means that exploitation does not require physical access to the device, making it particularly dangerous for network-connected devices. This vulnerability could enable attackers to gather intelligence about the device's configuration, potentially leading to further exploitation or privilege escalation within the network infrastructure.
Security mitigation strategies for this vulnerability should focus on implementing proper input validation and sanitization within the webserver component. Organizations should ensure that all URI paths are properly validated and that directory traversal sequences are rejected or properly encoded before processing. The implementation of proper access controls and sandboxing mechanisms within the webserver can prevent unauthorized file access attempts. Additionally, regular firmware updates and security patches should be deployed to address known vulnerabilities. This remediation approach aligns with the ATT&CK framework's mitigation strategies for privilege escalation and credential access techniques, particularly addressing the use of valid accounts and exploitation of vulnerabilities as outlined in the technique descriptions. System administrators should also consider network segmentation and access control measures to limit potential attack surfaces and reduce the impact of successful exploitation attempts.