CVE-2008-7159 in Silc Toolkit
Summary
by MITRE
The silc_asn1_encoder function in lib/silcasn1/silcasn1_encode.c in Secure Internet Live Conferencing (SILC) Toolkit before 1.1.8 allows remote attackers to overwrite a stack location and possibly execute arbitrary code via a crafted OID value, related to incorrect use of a %lu format string.
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Analysis
by VulDB Data Team • 08/22/2021
The vulnerability identified as CVE-2008-7159 represents a critical stack-based buffer overflow condition within the Secure Internet Live Conferencing (SILC) Toolkit library. This flaw exists in the silc_asn1_encoder function located in lib/silcasn1/silcasn1_encode.c, specifically affecting versions prior to 1.1.8. The vulnerability stems from improper handling of ASN.1 encoding operations where a crafted OID value can trigger memory corruption through incorrect format string usage. The SILC Toolkit serves as a comprehensive framework for secure internet communications, implementing various cryptographic protocols and mechanisms for real-time conferencing and messaging systems.
The technical exploitation of this vulnerability occurs through a format string vulnerability that allows attackers to manipulate the stack memory layout during ASN.1 encoding operations. When processing a crafted OID value, the function incorrectly utilizes a %lu format specifier without proper bounds checking or validation of the input data. This improper format string handling enables attackers to overwrite adjacent stack memory locations, potentially leading to arbitrary code execution. The vulnerability specifically targets the stack memory management during the encoding process, where the function fails to validate the length or structure of the OID data before performing format string operations. The flaw aligns with CWE-121 Stack-based Buffer Overflow, which describes vulnerabilities where data written to a buffer extends beyond the buffer's boundaries and overwrites adjacent memory locations.
The operational impact of this vulnerability extends beyond simple code execution, as it can enable remote attackers to gain unauthorized control over systems running vulnerable versions of the SILC Toolkit. Attackers can leverage this vulnerability to execute malicious code with the privileges of the affected process, potentially leading to complete system compromise. The remote nature of the attack means that exploitation can occur without requiring local access to the target system, making it particularly dangerous in networked environments where SILC services are exposed to external traffic. This vulnerability affects various applications and services that utilize the SILC Toolkit for secure communications, including instant messaging systems, secure conferencing platforms, and other real-time communication applications that depend on the toolkit's ASN.1 encoding capabilities.
Mitigation strategies for this vulnerability require immediate patching of affected systems to upgrade to SILC Toolkit version 1.1.8 or later, which contains the necessary fixes for the format string handling issue. Organizations should also implement network segmentation and access controls to limit exposure of vulnerable services to untrusted networks. The remediation process should include comprehensive vulnerability scanning to identify all systems running affected versions of the toolkit, followed by coordinated patch deployment and system validation. Additionally, security monitoring should be enhanced to detect potential exploitation attempts through unusual network traffic patterns or memory corruption indicators. This vulnerability demonstrates the critical importance of proper input validation and format string handling in cryptographic libraries, aligning with ATT&CK technique T1059.007 for command and scripting interpreter and T1547.001 for registry run keys or startup folder, as attackers may attempt to establish persistence through compromised systems. Organizations should also consider implementing automated patch management systems to ensure timely deployment of security updates and prevent similar vulnerabilities from remaining unpatched in production environments.