CVE-2017-5595 in ZoneMinder
Summary
by MITRE
A file disclosure and inclusion vulnerability exists in web/views/file.php in ZoneMinder 1.x through v1.30.0 because of unfiltered user-input being passed to readfile(), which allows an authenticated attacker to read local system files (e.g., /etc/passwd) in the context of the web server user (www-data). The attack vector is a .. (dot dot) in the path parameter within a zm/index.php?view=file&path= request.
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Analysis
by VulDB Data Team • 08/26/2024
The vulnerability described in CVE-2017-5595 represents a critical path traversal flaw in ZoneMinder version 1.30.0 and earlier, where the web application fails to properly sanitize user input before passing it to the readfile() function. This weakness enables authenticated attackers to access arbitrary files on the underlying file system through a carefully crafted request that includes directory traversal sequences. The vulnerability specifically affects the file.php component within the web/views directory, making it a prime target for attackers seeking to extract sensitive system information. The flaw operates by accepting user-supplied path parameters without adequate validation or filtering, allowing malicious input to bypass normal access controls and directly reference system files.
The technical execution of this vulnerability relies on the exploitation of directory traversal sequences, particularly the ".." (dot dot) notation that allows navigation up directory levels. When an attacker crafts a request to zm/index.php?view=file&path= with a path parameter containing traversal sequences such as ../../../etc/passwd, the application processes this input directly to the readfile() function without proper sanitization. This design flaw creates a direct path to arbitrary file reading capabilities, enabling attackers to access files that should normally be restricted to authorized users only. The vulnerability is particularly dangerous because it operates within the context of the web server user account, typically www-data, which may have elevated privileges to read sensitive system files, configuration data, and potentially database credentials or application secrets.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with the ability to access critical system resources that could lead to further compromise of the affected system. An attacker who successfully exploits this vulnerability can obtain sensitive files such as /etc/passwd, /etc/shadow, or application configuration files that may contain database connection strings, API keys, or other credentials. This information can then be used to escalate privileges or launch additional attacks against the system or network. The vulnerability is particularly concerning in environments where ZoneMinder is deployed for surveillance purposes, as it could potentially expose camera configuration data, user credentials, or other sensitive operational information that could be leveraged for unauthorized access or disruption of security services.
The vulnerability aligns with CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. This weakness is classified as a direct result of inadequate input validation and sanitization, where user-provided data is not properly filtered before being used in file system operations. From an adversarial perspective, this vulnerability maps to several ATT&CK techniques including T1083 (File and Directory Discovery) and T1005 (Data from Local System), as attackers can systematically explore and extract sensitive files from the compromised system. The authentication requirement for exploitation suggests this is a privilege escalation or lateral movement vector rather than a direct remote code execution vulnerability, but the potential for information gathering remains significant.
Mitigation strategies for CVE-2017-5595 should focus on implementing proper input validation and sanitization mechanisms before any user-supplied data is processed by file system operations. The most effective approach involves implementing strict path validation that rejects any input containing directory traversal sequences or other potentially dangerous characters. Organizations should ensure that all user inputs are properly sanitized and normalized before being passed to functions like readfile(), and implement whitelist-based validation that only allows specific, expected file paths. Additionally, the web server should be configured with appropriate access controls that limit the ability of the web application to access sensitive system files, and regular security audits should be conducted to identify and remediate similar vulnerabilities in other components of the application. The vulnerability demonstrates the critical importance of input validation and proper access controls in preventing unauthorized file access and information disclosure attacks.