CVE-2008-1429 in Silc-server
Summary
by MITRE
Secure Internet Live Conferencing (SILC) Server before 1.1.1 allows remote attackers to cause a denial of service (daemon crash) via a NEW_CLIENT packet without a nickname.
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Analysis
by VulDB Data Team • 08/09/2019
The vulnerability identified as CVE-2008-1429 affects the Secure Internet Live Conferencing SILC Server version 1.1.0 and earlier, representing a critical denial of service weakness that can be exploited by remote attackers to crash the daemon service. This vulnerability specifically targets the server's handling of client connection packets, particularly the NEW_CLIENT packet which is fundamental to the SILC protocol's client-server communication framework. The flaw exists in the server's packet validation logic where it fails to properly handle client connection requests that lack essential identifying information, specifically the nickname field that is typically required for client registration within the SILC network infrastructure.
The technical nature of this vulnerability stems from inadequate input validation within the SILC server's protocol implementation, where the daemon does not properly check for the presence of required fields in the NEW_CLIENT packet before attempting to process the connection request. This represents a classic buffer overflow or null pointer dereference scenario that occurs when the server attempts to access memory locations or process data structures without verifying that the expected fields are present in the incoming packet. The vulnerability maps to CWE-476 which describes NULL Pointer Dereference, and more broadly to CWE-20 which encompasses Improper Input Validation. The flaw demonstrates a fundamental security weakness in the server's robustness and error handling capabilities, where the system fails gracefully when encountering malformed packets rather than implementing proper defensive mechanisms.
From an operational perspective, this vulnerability presents significant risk to organizations relying on SILC servers for secure communication services, as it allows remote attackers to disrupt service availability without requiring authentication or specialized privileges. The denial of service impact can be severe as it effectively renders the SILC server unavailable to legitimate users, potentially disrupting real-time communication channels and collaborative environments that depend on the service. Attackers can exploit this vulnerability by simply sending a specially crafted NEW_CLIENT packet that omits the nickname field, causing the server daemon to crash and restart, which may result in service interruption and potential data loss. This vulnerability aligns with ATT&CK technique T1499.004 which describes Network Denial of Service, and specifically targets the availability aspect of the CIA triad by compromising service accessibility.
The recommended mitigations for this vulnerability include immediate patching of the SILC server to version 1.1.1 or later, which contains the necessary fixes to properly validate client connection packets and handle missing nickname fields gracefully. Organizations should also implement network monitoring to detect unusual packet patterns that may indicate exploitation attempts, and establish proper input validation procedures within their network infrastructure to prevent malformed packets from reaching the vulnerable server components. Additionally, deploying intrusion detection systems that can identify and block suspicious NEW_CLIENT packet patterns will provide an additional layer of defense. The vulnerability highlights the importance of robust error handling and input validation in security-critical applications, emphasizing that all external inputs must be validated and sanitized before processing to prevent exploitation of similar weaknesses in other components of the communication infrastructure.