CVE-2001-0834 in ht:
Summary
by MITRE
htsearch CGI program in htdig (ht://Dig) 3.1.5 and earlier allows remote attackers to use the -c option to specify an alternate configuration file, which could be used to (1) cause a denial of service (CPU consumption) by specifying a large file such as /dev/zero, or (2) read arbitrary files by uploading an alternate configuration file that specifies the target file.
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Analysis
by VulDB Data Team • 10/04/2025
The CVE-2001-0834 vulnerability resides within the htsearch CGI program of htdig version 3.1.5 and earlier, representing a critical security flaw that enables remote attackers to manipulate the search functionality through improper configuration file handling. This vulnerability specifically exploits the -c command-line option which allows users to specify an alternate configuration file, creating a pathway for both denial of service attacks and unauthorized file access. The ht://Dig project was a widely used web search engine that indexed web content through automated crawling processes, making this vulnerability particularly dangerous in environments where search functionality was exposed to external users.
The technical flaw manifests through the improper validation of user-supplied configuration file paths, allowing attackers to craft malicious input that bypasses normal file access controls. When the -c option is utilized, the htsearch program accepts any file path provided by the attacker without adequate sanitization or access control checks. This creates two distinct attack vectors: the first involves specifying large files such as /dev/zero to consume excessive CPU resources and memory, leading to denial of service conditions where legitimate search operations become impossible. The second vector enables attackers to read arbitrary files from the system by uploading specially crafted configuration files that reference sensitive target files, potentially exposing system information, configuration data, or even user credentials stored in accessible locations.
The operational impact of this vulnerability extends beyond simple service disruption to encompass serious data confidentiality risks. Attackers can leverage this flaw to extract sensitive information from the system, including but not limited to system configuration files, database connection details, or application-specific data that might be referenced in the configuration files. The vulnerability's exploitation requires minimal technical skill and can be executed through standard web browser interactions, making it particularly dangerous as it allows automated attacks against vulnerable systems. This flaw particularly affects web servers running htdig search functionality where the htsearch CGI program is accessible to unauthenticated users, creating an attack surface that could be exploited by anyone with access to the web interface.
Mitigation strategies for CVE-2001-0834 should prioritize immediate patching of affected systems, with the most effective solution being the upgrade to htdig versions that address this specific vulnerability. System administrators should implement restrictive file access controls on the htsearch program and its associated configuration directories, ensuring that only authorized users can access or modify these critical components. Network-level protections such as web application firewalls can help detect and block malicious requests containing the -c parameter with suspicious file paths. Additionally, implementing proper input validation and sanitization measures within the application code can prevent the acceptance of arbitrary file paths. From a compliance perspective, this vulnerability aligns with CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) and CWE-77 (Improper Neutralization of Special Elements used in a Command), and represents a technique categorized under ATT&CK tactic TA0043 (Reconnaissance) and technique T1213 (Data from Information Repositories) for information gathering and data exfiltration activities. Organizations should also consider implementing monitoring and alerting mechanisms to detect unusual CPU consumption patterns or unauthorized file access attempts that might indicate exploitation of this vulnerability.