CVE-2002-1358 in PuTTY
Summary
by MITRE
Multiple SSH2 servers and clients do not properly handle lists with empty elements or strings, which may allow remote attackers to cause a denial of service or possibly execute arbitrary code, as demonstrated by the SSHredder SSH protocol test suite.
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Analysis
by VulDB Data Team • 06/17/2024
The vulnerability described in CVE-2002-1358 represents a critical flaw in SSH2 implementations that affects both server and client components across multiple vendors. This weakness stems from improper handling of malformed data structures, specifically lists containing empty elements or strings during SSH protocol negotiations. The issue manifests when SSH2 implementations fail to validate or properly process these edge cases in protocol communications, creating potential attack vectors that can be exploited by remote adversaries. The vulnerability was particularly significant because SSH2 was becoming widely adopted for secure remote access and network communications, making any flaws in its implementation potentially devastating to network security infrastructure.
The technical root cause of this vulnerability lies in the insufficient input validation mechanisms within SSH2 protocol implementations. When processing SSH2 protocol messages containing lists with empty elements, the affected systems fail to properly sanitize or reject malformed data structures. This parsing error creates a condition where attackers can craft specially crafted protocol messages that trigger unexpected behavior in the target implementation. The flaw typically occurs during key exchange, authentication, or session establishment phases where SSH2 clients and servers must process structured data containing potentially empty list elements. According to CWE classification, this vulnerability maps to CWE-129: Improper Validation of Array Index, as the systems fail to properly validate the bounds and content of data structures. The vulnerability can be categorized under CWE-20: Improper Input Validation, specifically manifesting as improper handling of malformed data structures in protocol implementations.
The operational impact of CVE-2002-1358 extends beyond simple denial of service to potentially enabling remote code execution in vulnerable implementations. Attackers can exploit this weakness by sending specially crafted SSH2 protocol messages that contain empty elements in lists, causing the target system to crash or behave unpredictably. In some implementations, this malformed data processing can lead to buffer overflows or other memory corruption conditions that may allow arbitrary code execution. The SSHredder SSH protocol test suite demonstrated this vulnerability by creating test cases that specifically targeted these parsing weaknesses, showing that even legitimate protocol implementations could be exploited through carefully crafted malformed data. The attack surface is particularly wide given that SSH2 was being adopted across enterprise networks, cloud environments, and critical infrastructure systems where remote access was essential. From an ATT&CK framework perspective, this vulnerability aligns with T1210: Exploitation of Remote Services and T1059: Command and Scripting Interpreter, as it enables adversaries to compromise systems through protocol-level exploitation and potentially gain execution privileges.
Mitigation strategies for CVE-2002-1358 require immediate patching of affected SSH implementations, with system administrators prioritizing updates from vendors such as OpenSSH, SSH Communications Security, and other SSH2 implementations. Organizations should implement network segmentation and access controls to limit exposure to potentially compromised SSH services, while also deploying intrusion detection systems that can identify suspicious SSH protocol traffic patterns. Regular security assessments should include testing for proper handling of edge cases in protocol implementations, particularly focusing on data structure validation during key exchange and authentication phases. System administrators should also consider implementing SSH protocol monitoring and logging to detect anomalous behavior that might indicate exploitation attempts. The vulnerability underscores the importance of robust input validation and proper error handling in cryptographic protocol implementations, as highlighted in security standards such as NIST SP 800-53 and ISO/IEC 27001. Organizations should also maintain updated threat intelligence feeds to monitor for exploitation attempts targeting this specific vulnerability class and ensure that all SSH implementations undergo rigorous security testing for edge case handling before deployment in production environments.