CVE-2018-5762 in Clearpath MCP
Summary
by MITRE
The TLS implementation in the TCP/IP networking module in Unisys ClearPath MCP systems with TCP-IP-SW 58.1 before 58.160, 59.1 before 059.1a.17 (IC #17), and 60.0 before 60.044 might allow remote attackers to decrypt TLS ciphertext data by leveraging a Bleichenbacher RSA padding oracle, aka a ROBOT attack.
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Analysis
by VulDB Data Team • 01/08/2020
The vulnerability identified as CVE-2018-5762 represents a critical security flaw within the TLS implementation of Unisys ClearPath MCP systems, specifically affecting TCP-IP-SW versions prior to their respective security patches. This vulnerability stems from an insufficient implementation of RSA padding verification within the cryptographic subsystem, creating a pathway for remote attackers to exploit the system through a well-known cryptographic attack vector. The flaw manifests in systems running TCP-IP-SW version 58.1 before 58.160, 59.1 before 059.1a.17, and 60.0 before 60.044, making these deployments particularly susceptible to targeted attacks that could compromise the confidentiality of encrypted communications.
The technical exploitation of this vulnerability relies on the Bleichenbacher RSA padding oracle attack, which was first demonstrated by Daniel Bleichenbacher in 1998 and later refined in the context of the ROBOT (Return Of the Bleichenbacher's Oracle Threat) attack. This attack exploits the way the system handles RSA decryption operations, specifically when the system returns different error messages depending on whether the RSA padding is valid or invalid. This oracle allows an attacker to iteratively determine the plaintext of encrypted data through multiple queries, effectively breaking the encryption. The attack operates by sending specially crafted RSA ciphertexts to the vulnerable system and observing the responses to deduce the original plaintext, thereby enabling the decryption of TLS ciphertext data without possessing the corresponding private keys.
The operational impact of this vulnerability extends beyond simple data confidentiality breaches, as it fundamentally undermines the security assurances provided by TLS encryption in mission-critical environments. Organizations utilizing Unisys ClearPath MCP systems in sensitive sectors such as financial services, healthcare, or government operations face significant risks when these systems remain unpatched, as attackers could potentially intercept and decrypt sensitive communications including authentication credentials, personal data, and proprietary information. The vulnerability particularly affects systems where TLS is used for secure remote access, database communications, and web services, making it a serious concern for enterprises maintaining legacy infrastructure that continues to support critical business processes.
Mitigation strategies for CVE-2018-5762 require immediate implementation of vendor-provided security patches and updates to the affected TCP-IP-SW versions, specifically upgrading to versions 58.160, 059.1a.17, and 60.044 respectively. Organizations should also consider implementing additional security controls such as disabling vulnerable RSA key sizes, implementing proper monitoring for unusual cryptographic operations, and conducting thorough vulnerability assessments to identify any other potential cryptographic weaknesses in their network infrastructure. From a cybersecurity perspective, this vulnerability aligns with CWE-327, which addresses the use of weak cryptographic algorithms and improper implementation of cryptographic functions, and maps to ATT&CK techniques related to credential access and defense evasion through exploitation of cryptographic vulnerabilities. System administrators should also consider implementing network segmentation and additional monitoring to detect potential exploitation attempts, while maintaining awareness of the broader implications of legacy system vulnerabilities in modern threat landscapes.