CVE-2002-1359 in PuTTY
Summary
by MITRE
Multiple SSH2 servers and clients do not properly handle large packets or large fields, which may allow remote attackers to cause a denial of service or possibly execute arbitrary code via buffer overflow attacks, as demonstrated by the SSHredder SSH protocol test suite.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 07/05/2025
The vulnerability identified as CVE-2002-1359 represents a critical buffer overflow issue affecting SSH2 implementations across multiple server and client platforms. This flaw stems from inadequate handling of oversized packets and fields within the SSH2 protocol stack, creating exploitable conditions that can be leveraged by remote attackers to compromise system integrity. The vulnerability was particularly significant because SSH2 was becoming the standard for secure remote access, making widespread exploitation potential a serious concern for network security infrastructure.
The technical implementation of this vulnerability occurs when SSH2 servers and clients fail to validate packet sizes and field dimensions before processing incoming data. When malformed or oversized packets are received, the protocol implementations do not properly bounds-check the data structures, leading to memory corruption that manifests as buffer overflows. These buffer overflows can occur during various stages of the SSH2 handshake process, key exchange operations, or data transmission phases where large data fields are processed. The specific nature of the flaw allows attackers to craft malicious packets that exceed the allocated buffer space, causing memory corruption that can result in program termination or potentially arbitrary code execution.
The operational impact of CVE-2002-1359 extends beyond simple denial of service conditions to encompass potential system compromise and unauthorized access. Remote attackers can exploit this vulnerability to cause service disruption by triggering buffer overflows that crash SSH services, rendering systems inaccessible to legitimate users. However, the more dangerous aspect involves potential code execution capabilities that could allow attackers to gain unauthorized access to systems running vulnerable SSH implementations. This makes the vulnerability particularly attractive to threat actors seeking to establish persistent access to network infrastructure, as SSH services are commonly used for administrative access to critical systems.
The SSHredder SSH protocol test suite demonstrated the exploitability of this vulnerability by creating specific packet structures that would trigger the buffer overflow conditions in multiple SSH2 implementations. This validation confirmed that the issue was not isolated to a single vendor's implementation but rather represented a fundamental flaw in how SSH2 protocols were handling large data structures across different software platforms. The vulnerability's exploitation typically requires minimal network access and can be automated, making it particularly dangerous in environments where SSH services are widely deployed. Organizations with vulnerable SSH implementations face significant risk of unauthorized access, data compromise, and potential lateral movement within their networks.
Mitigation strategies for CVE-2002-1359 require immediate patching of affected SSH implementations and implementation of network-level controls to monitor for suspicious packet patterns. System administrators should prioritize updating SSH software to versions that properly validate packet sizes and implement robust bounds checking mechanisms. Network segmentation and access control measures can help limit the potential impact of exploitation by restricting access to SSH services to authorized users and systems. Additionally, implementing intrusion detection systems that can identify and block malformed SSH packets can provide defense-in-depth protection against this class of vulnerability. The vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and represents a specific implementation weakness in the SSH2 protocol that violates security best practices established in industry standards for secure protocol design.
The broader implications of this vulnerability highlight the critical importance of proper input validation and bounds checking in network protocol implementations. This flaw demonstrates how seemingly minor implementation details in cryptographic protocols can create significant security weaknesses that affect entire ecosystems. Organizations should implement comprehensive security testing procedures that include protocol-level validation and boundary condition testing to identify similar vulnerabilities before they can be exploited by adversaries. The vulnerability also underscores the need for continuous security monitoring and rapid response capabilities to address emerging threats in widely deployed network services.