CVE-2003-0083 in HTTP Server
Summary
by MITRE
Apache 1.3 before 1.3.25 and Apache 2.0 before version 2.0.46 does not filter terminal escape sequences from its access logs, which could make it easier for attackers to insert those sequences into terminal emulators containing vulnerabilities related to escape sequences, a different vulnerability than CVE-2003-0020.
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Analysis
by VulDB Data Team • 08/25/2025
The vulnerability identified as CVE-2003-0083 represents a critical security flaw in Apache web server versions prior to 1.3.25 and 2.0.46, specifically addressing the improper handling of terminal escape sequences within access log files. This issue arises from the server's failure to sanitize escape sequences that may be present in user input, particularly in HTTP requests that are logged to the access log files. When these logs are subsequently viewed in terminal emulators or text editors that interpret escape sequences, attackers can potentially exploit this behavior to inject malicious commands or manipulate the terminal display.
The technical flaw stems from the absence of proper input validation and sanitization mechanisms within Apache's logging subsystem. When user agents submit requests containing escape sequences such as ANSI escape codes, these sequences are directly written to the access log files without filtering or encoding. This behavior creates a potential attack vector where an attacker could craft HTTP requests containing malicious escape sequences that would be executed when the log file is viewed in a terminal environment. The vulnerability operates under the principle that log files can become attack surfaces when they contain unfiltered user input, particularly in environments where these logs are regularly examined by system administrators.
The operational impact of this vulnerability extends beyond simple logging concerns and can lead to significant security implications in environments where Apache access logs are regularly reviewed. When administrators or automated tools parse these log files using terminal emulators or text viewers that support escape sequences, attackers can potentially execute arbitrary commands or manipulate terminal sessions. This creates a scenario where the vulnerability becomes a persistent threat vector that could be exploited over time as logs are reviewed and analyzed. The risk is particularly elevated in environments where log files are accessed using vulnerable terminal applications or where log viewing tools do not properly sanitize escape sequences, potentially allowing attackers to perform terminal-based attacks such as command injection or display manipulation.
This vulnerability aligns with CWE-117, which addresses improper output neutralization for logs, and demonstrates how logging mechanisms can become attack surfaces when they fail to properly sanitize user input. The issue also relates to ATT&CK technique T1070.004, which involves the manipulation of log data to evade detection or gain additional access. Organizations using affected Apache versions face the risk of indirect command execution through log file viewing activities, making this vulnerability particularly dangerous in administrative environments where logs are frequently monitored. The attack vector differs from CVE-2003-0020 as it specifically targets the terminal rendering of log files rather than the web server itself, though both vulnerabilities highlight the importance of proper input sanitization in web server components.
Mitigation strategies for CVE-2003-0083 require immediate patching of affected Apache installations to versions 1.3.25 and 2.0.46 or later, which contain proper escape sequence filtering mechanisms. Organizations should also implement additional defensive measures including the use of log viewers that properly sanitize escape sequences, regular log file monitoring for suspicious content, and the implementation of centralized logging solutions that provide better control over log data presentation. System administrators should be trained to recognize potential escape sequence injection attempts and implement proper log rotation and access controls to limit exposure. Additionally, organizations should consider implementing web application firewalls or intrusion detection systems that can identify and block requests containing potentially malicious escape sequences, providing an additional layer of protection against this specific vulnerability.