CVE-2008-0408 in HTTP File Server
Summary
by MITRE
HTTP File Server (HFS) before 2.2c allows remote attackers to append arbitrary text to the log file by using the base64 representation of this text during HTTP Basic Authentication.
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Analysis
by VulDB Data Team • 11/07/2017
HTTP File Server version 2.2c and earlier contains a critical logging vulnerability that enables remote attackers to inject arbitrary text into the server's log files through manipulated HTTP Basic Authentication headers. This flaw resides in how the software processes authentication requests and handles base64 encoded credentials, creating an injection vector that can be exploited without requiring authentication privileges. The vulnerability specifically affects the logging mechanism that records authentication attempts, allowing malicious actors to append arbitrary content to log files through carefully crafted base64 encoded strings.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization within the HTTP Basic Authentication processing pipeline. When a client submits authentication credentials using HTTP Basic Authentication, the server base64 decodes these credentials and subsequently logs them to the file system. However, the logging component fails to properly sanitize the decoded data, permitting attackers to inject malicious content that gets written directly to the log file. This represents a classic case of inadequate output escaping and improper input filtering, which aligns with CWE-117 - Improper Output Neutralization for Logs and CWE-77 - Improper Neutralization of Special Elements used in a Command.
The operational impact of this vulnerability extends beyond simple log file corruption, as it can be leveraged for more sophisticated attacks including log poisoning, command injection, and potential privilege escalation within the server environment. Attackers can use this technique to inject malicious content that might be interpreted by log analysis tools or monitoring systems, potentially leading to further compromise of the server infrastructure. The vulnerability also violates fundamental security principles by allowing unauthorized modification of server logs, which are critical for security monitoring and incident response activities. This weakness can be categorized under ATT&CK technique T1070.002 - Indicator Removal on Host: File Deletion, as it enables attackers to modify system logs to cover their tracks.
Mitigation strategies should focus on immediate software updates to version 2.2c or later, which contain the necessary fixes for this logging vulnerability. Organizations should also implement strict input validation for all HTTP headers and authentication requests, ensuring that any base64 encoded data is properly sanitized before logging. Network monitoring should be enhanced to detect unusual patterns in log file modifications, and regular log integrity checks should be performed to identify potential injection attempts. Additionally, implementing proper access controls and authentication mechanisms, along with regular security assessments, can help prevent exploitation of similar vulnerabilities in other software components. The fix addresses the root cause by implementing proper input sanitization and output escaping for log entries, ensuring that all authentication data is properly neutralized before being written to persistent storage.