CVE-2005-2809 in Secure Internet Live Conferencing
Summary
by MITRE
silc daemon (silcd.c) in Secure Internet Live Conferencing (SILC) 1.0 and earlier allows local users to overwrite arbitrary files via a symlink attack on the silcd.[PID].stats temporary file.
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Analysis
by VulDB Data Team • 06/24/2018
The vulnerability identified as CVE-2005-2809 affects the Secure Internet Live Conferencing (SILC) daemon implementation, specifically within the silcd.c component of SILC version 1.0 and earlier. This represents a critical security flaw that enables local attackers to manipulate the system through a carefully crafted symlink attack against temporary file handling mechanisms. The vulnerability resides in how the daemon manages temporary files during its operation, creating an opportunity for privilege escalation and arbitrary file modification.
The technical flaw manifests through improper handling of temporary files with predictable naming patterns. When the SILC daemon operates, it creates temporary files named silcd.[PID].stats where PID represents the process identifier. Local users can exploit this predictable naming convention by creating symbolic links with the same names before the daemon attempts to write to these files. This symlink attack allows attackers to redirect the daemon's write operations to arbitrary locations on the filesystem, potentially overwriting critical system files or configuration data. The vulnerability directly relates to CWE-377, which addresses insecure temporary file creation practices, and CWE-378, which covers the creation of temporary files with insecure permissions.
The operational impact of this vulnerability extends beyond simple file overwriting capabilities. Attackers can leverage this weakness to modify system configuration files, inject malicious code into the daemon process, or even escalate privileges if the daemon runs with elevated permissions. The attack requires local system access but does not necessitate network connectivity, making it particularly dangerous in environments where local privilege escalation is a concern. This vulnerability can be exploited to maintain persistent access to systems, modify audit trails, or compromise the integrity of the entire SILC communication infrastructure. The attack vector aligns with ATT&CK technique T1059.001 for executing commands through the daemon process and T1078 for gaining access through local accounts.
Mitigation strategies for this vulnerability involve immediate patching of the SILC daemon to version 1.1 or later where the temporary file handling has been corrected. System administrators should ensure that temporary files are created with proper permissions and atomic operations to prevent symlink attacks. The recommended approach includes implementing proper file descriptor management, using secure temporary file creation functions, and ensuring that daemon processes run with minimal required privileges. Additionally, monitoring for suspicious temporary file creation patterns and implementing proper file system permissions can help detect and prevent exploitation attempts. Organizations should also consider implementing mandatory access controls and regular security audits to identify similar vulnerabilities in other software components.