CVE-2002-1360 in PuTTY
Summary
by MITRE
Multiple SSH2 servers and clients do not properly handle strings with null characters in them when the string length is specified by a length field, which could allow remote attackers to cause a denial of service or possibly execute arbitrary code due to interactions with the use of null-terminated strings as implemented using languages such as C, as demonstrated by the SSHredder SSH protocol test suite.
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Analysis
by VulDB Data Team • 06/17/2024
This vulnerability affects Secure Shell version 2 implementations across both server and client components, exploiting a fundamental flaw in how null-terminated strings are processed within the protocol's string handling mechanisms. The issue stems from improper validation of string lengths when length fields are used to specify string boundaries rather than relying on null termination. In C-based implementations, this creates a dangerous scenario where attackers can manipulate string data to bypass length checks, potentially leading to buffer overflows or other memory corruption issues. The vulnerability manifests when SSH2 protocol implementations encounter strings containing null characters that are embedded within data structures where length fields are used to determine string boundaries, creating a mismatch between the declared length and the actual string content.
The technical exploitation occurs through carefully crafted malicious packets that contain strings with embedded null characters, where the length field indicates a different size than the actual string content. This discrepancy can cause the SSH implementation to process the string incorrectly, potentially leading to memory corruption that could result in denial of service conditions or in some cases arbitrary code execution. The vulnerability is particularly dangerous because it leverages the inherent weaknesses of null-terminated string handling in C programming languages, where functions like strcpy and strcat do not check for buffer boundaries when encountering null characters. This creates opportunities for attackers to manipulate memory layout and potentially execute malicious code within the context of the SSH process. The specific exploitation vector was demonstrated through the SSHredder SSH protocol test suite, which revealed how null character insertion could trigger unexpected behavior in the protocol parsing logic.
The operational impact of CVE-2002-1360 extends beyond simple denial of service to potentially enable remote code execution in vulnerable implementations, making it a critical security concern for any systems relying on SSH2 for remote access and administration. Organizations running affected SSH2 implementations face significant risk of unauthorized access, system compromise, and potential data breaches. The vulnerability affects a broad range of SSH2 implementations including popular open source and commercial products, making it particularly widespread. Systems that depend on SSH2 for secure communications, remote administration, and automated operations are all at risk, with the potential for attackers to gain persistent access to network resources. The impact is compounded by the fact that SSH2 is widely used in enterprise environments for critical infrastructure management, making successful exploitation potentially devastating for organizations.
Mitigation strategies for CVE-2002-1360 require immediate patching of affected SSH2 implementations, with organizations prioritizing updates from their vendors or applying security patches from trusted sources. The vulnerability is classified under CWE-129 Input Validation and CWE-120 Buffer Overflow, with potential ATT&CK techniques including T1059 Command and Scripting Interpreter and T1499 Endpoint Denial of Service. Network administrators should implement additional monitoring and intrusion detection measures to identify potential exploitation attempts, particularly looking for malformed SSH packets containing null characters in string fields. System hardening measures including disabling unnecessary SSH2 features, implementing strict access controls, and deploying network segmentation can help reduce the attack surface. Organizations should also consider implementing automated patch management processes to ensure timely deployment of security updates. The vulnerability highlights the importance of proper string handling in security-critical applications and reinforces the need for comprehensive input validation and boundary checking in all network protocol implementations. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other network protocols and applications.