CVE-2001-1470 in SSH
Summary
by MITRE
The IDEA cipher as implemented by SSH1 does not protect the final block of a message against modification, which allows remote attackers to modify the block without detection by changing its cyclic redundancy check (CRC) to match the modifications to the message.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 11/17/2024
The vulnerability described in CVE-2001-1470 represents a critical cryptographic flaw in the implementation of the International Data Encryption Algorithm within Secure Shell version 1 protocol. This weakness specifically targets the integrity protection mechanisms of SSH1's encryption implementation, creating a scenario where attackers can manipulate encrypted data without detection. The issue stems from an improper handling of the final block in the encryption process, which fundamentally undermines the security assurances that cryptographic protocols are designed to provide.
The technical root cause of this vulnerability lies in the flawed implementation of the IDEA cipher's block processing within SSH1's cryptographic framework. When encrypting data, SSH1 processes messages in blocks and applies cyclic redundancy check mechanisms to ensure data integrity. However, the implementation fails to properly secure the final block of data, allowing attackers to modify the encrypted content while simultaneously adjusting the CRC value to match the altered data. This creates a situation where the cryptographic checksum verification becomes ineffective, as the attacker can manipulate both the encrypted data and its accompanying integrity check. The vulnerability specifically affects the way the final block is handled during the encryption process, where the integrity protection mechanism is either absent or insufficiently applied.
The operational impact of this vulnerability extends beyond simple data modification, as it fundamentally compromises the security model of SSH1 connections. Attackers can exploit this weakness to perform man-in-the-middle attacks, modify sensitive data during transmission, or manipulate authentication processes without detection by the receiving system. The vulnerability affects all implementations of SSH1 that utilize the IDEA cipher for encryption, making it particularly dangerous given the widespread adoption of SSH1 in network infrastructure. This weakness allows adversaries to potentially alter login credentials, system commands, or other sensitive information transmitted through SSH1 connections, undermining the confidentiality and integrity guarantees that users expect from secure communication protocols.
This vulnerability aligns with CWE-310, which addresses cryptographic weakness, and specifically relates to improper implementation of cryptographic integrity checks within network protocols. The flaw demonstrates a clear violation of the principle of authenticated encryption, where both confidentiality and integrity must be maintained simultaneously. From an ATT&CK perspective, this vulnerability maps to T1566, which covers phishing techniques, as attackers can exploit the modified data to gain unauthorized access or manipulate system behavior. The weakness also connects to T1071, which deals with application layer protocols, as it affects SSH protocol implementation. Organizations using SSH1 with IDEA cipher implementations face significant risk of undetected data manipulation, making this vulnerability particularly dangerous for environments where secure communication is critical. The remediation strategy requires immediate migration to SSH2 protocol implementations, which properly address these cryptographic integrity concerns, along with the implementation of additional network monitoring to detect potential exploitation attempts.