CVE-2000-0857 in muh
Summary
by MITRE
The logging capability in muh 2.05d IRC server does not properly cleanse user-injected format strings, which allows remote attackers to cause a denial of service or execute arbitrary commands via a malformed nickname.
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Analysis
by VulDB Data Team • 05/27/2018
The vulnerability described in CVE-2000-0857 represents a critical security flaw in the muh 2.05d Internet Relay Chat server implementation that stems from improper handling of user input within logging functions. This issue manifests when the IRC server processes user nicknames that contain format string specifiers, which are typically used in programming contexts to control output formatting. The server fails to properly sanitize or escape these format specifiers before incorporating them into log messages, creating a potential vector for exploitation that can be leveraged by remote attackers to manipulate the server's behavior.
The technical mechanism behind this vulnerability operates through format string injection attacks that exploit weaknesses in how the muh IRC server handles string formatting operations within its logging subsystem. When a user connects to the IRC server with a nickname containing format specifiers such as %s, %d, or other printf-style formatting characters, the server's logging function processes this input without adequate validation or sanitization. This allows attackers to inject malicious format specifiers that can cause the logging function to read from memory locations or execute unintended operations, potentially leading to arbitrary code execution or denial of service conditions.
The operational impact of this vulnerability extends beyond simple service disruption to encompass potential complete system compromise. Attackers can leverage this flaw to cause the IRC server to crash or behave unpredictably, resulting in denial of service for legitimate users. More critically, the format string injection could enable arbitrary code execution if the server process has sufficient privileges, allowing attackers to gain unauthorized access to the system hosting the IRC server. This vulnerability affects the availability and integrity of the IRC service, potentially compromising the entire infrastructure that relies on the server for communication.
Mitigation strategies for this vulnerability require immediate implementation of input validation and sanitization measures within the IRC server's logging functionality. System administrators should ensure that all user-supplied input, particularly nicknames and other identifying information, undergo proper cleansing before being processed by logging functions. The recommended approach involves implementing strict validation of input characters and escaping special format specifiers to prevent their interpretation by string formatting functions. Additionally, this vulnerability highlights the importance of following secure coding practices and adhering to standards such as the CWE (Common Weakness Enumeration) classification for format string vulnerabilities, which falls under CWE-134. Organizations should also consider implementing network segmentation and access controls to limit exposure, while monitoring for suspicious connection patterns that may indicate exploitation attempts. The ATT&CK framework categorizes this type of vulnerability under privilege escalation and execution techniques, emphasizing the need for comprehensive security measures that address both the immediate flaw and broader system security posture.