CVE-2003-0101 in Webmin
Summary
by MITRE
miniserv.pl in (1) Webmin before 1.070 and (2) Usermin before 1.000 does not properly handle metacharacters such as line feeds and carriage returns (CRLF) in Base-64 encoded strings during Basic authentication, which allows remote attackers to spoof a session ID and gain root privileges.
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Analysis
by VulDB Data Team • 12/12/2024
The vulnerability described in CVE-2003-0101 represents a critical authentication bypass flaw in the miniserv.pl component of both Webmin and Usermin software versions prior to their respective secure releases. This issue stems from improper handling of metacharacters within Base-64 encoded strings during Basic authentication processes, creating a pathway for remote attackers to manipulate authentication mechanisms and escalate privileges to root level access. The vulnerability specifically affects Webmin versions before 1.070 and Usermin versions before 1.000, making these software versions susceptible to exploitation by malicious actors without requiring valid credentials.
The technical flaw manifests in the way miniserv.pl processes authentication headers containing Base-64 encoded credentials. When attackers craft malicious Base-64 strings that include carriage return and line feed characters, the authentication parser fails to properly sanitize these metacharacters before processing the authentication request. This improper input validation creates a condition where an attacker can inject additional authentication data or manipulate existing authentication tokens, effectively bypassing the standard authentication mechanism. The vulnerability operates at the protocol level of Basic authentication, where the attacker can exploit the lack of proper sanitization to inject malicious content that gets interpreted as legitimate authentication data.
The operational impact of this vulnerability is severe and far-reaching, as it allows remote attackers to completely bypass authentication mechanisms and gain full root privileges on affected systems. This privilege escalation capability means that an attacker who successfully exploits this vulnerability can execute arbitrary code, modify system files, access sensitive data, and potentially establish persistent access to the compromised system. The vulnerability's remote exploitability eliminates the need for physical access or local system compromise, making it particularly dangerous in networked environments where these services are exposed to the internet. The ability to spoof session IDs further compounds the risk, as it allows attackers to maintain access even after initial exploitation attempts.
Mitigation strategies for this vulnerability involve immediate upgrading to patched versions of Webmin and Usermin software, specifically versions 1.070 and 1.000 respectively, which contain proper sanitization of Base-64 encoded strings and metacharacter handling. Organizations should also implement network segmentation to limit exposure of these services to untrusted networks, disable unnecessary authentication mechanisms, and monitor for suspicious authentication attempts. The vulnerability aligns with CWE-20, which describes improper input validation, and maps to ATT&CK technique T1078 for valid accounts and privilege escalation. Additionally, this flaw demonstrates the importance of proper input sanitization in authentication systems, as outlined in OWASP Top 10 security principles, particularly in relation to authentication and session management controls that should prevent injection attacks against authentication mechanisms.