CVE-2003-0131 in OpenSSL
Summary
by MITRE
The SSL and TLS components for OpenSSL 0.9.6i and earlier, 0.9.7, and 0.9.7a allow remote attackers to perform an unauthorized RSA private key operation via a modified Bleichenbacher attack that uses a large number of SSL or TLS connections using PKCS #1 v1.5 padding that cause OpenSSL to leak information regarding the relationship between ciphertext and the associated plaintext, aka the "Klima-Pokorny-Rosa attack."
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Analysis
by VulDB Data Team • 01/19/2025
The vulnerability described in CVE-2003-0131 represents a critical security flaw in OpenSSL implementations that affects versions 0.9.6i and earlier, as well as versions 0.9.7 and 0.9.7a. This vulnerability specifically targets the SSL and TLS cryptographic components and exploits a mathematical weakness in the PKCS #1 v1.5 padding scheme used during RSA encryption operations. The attack leverages a modified version of the Bleichenbacher attack, which was originally demonstrated in 1998 and later refined by researchers Klima, Pokorny, and Rosa. This particular variant of the attack takes advantage of the way OpenSSL handles error responses during RSA decryption operations, creating a side-channel information leak that can be exploited by remote attackers.
The technical flaw resides in how OpenSSL processes RSA decryption operations when using PKCS #1 v1.5 padding. During SSL/TLS handshakes, when clients and servers perform RSA operations for key exchange or authentication, the system returns different error messages depending on whether the padding is valid or invalid. This differential response creates a timing or error-based side-channel that allows attackers to iteratively probe the system and gradually reconstruct the RSA private key. The vulnerability operates through a process of multiple SSL or TLS connections where each connection provides a small amount of information about the relationship between the ciphertext and plaintext, ultimately enabling the attacker to recover the private key through mathematical analysis and statistical inference.
The operational impact of this vulnerability is severe and far-reaching, as it allows remote attackers to completely compromise the security of SSL/TLS connections that rely on RSA encryption. Once an attacker successfully extracts the RSA private key, they can impersonate legitimate servers, decrypt sensitive communications, and potentially gain unauthorized access to systems that were previously considered secure. This attack is particularly dangerous because it can be executed without requiring direct access to the target system, making it a significant threat to web servers, email servers, and any infrastructure relying on SSL/TLS for secure communications. The vulnerability affects the fundamental security assumptions of the TLS protocol and undermines the confidentiality and integrity guarantees that users expect from encrypted communications.
The attack pattern aligns with several elements of the MITRE ATT&CK framework, particularly in the area of credential access through exploitation of cryptographic weaknesses and side-channel attacks. This vulnerability demonstrates how improper implementation of cryptographic protocols can create information leakage channels that bypass traditional security controls. From a CWE perspective, this issue relates to CWE-310: Cryptographic Issues, specifically addressing weaknesses in cryptographic implementation and key management. Organizations should implement immediate mitigations including upgrading to OpenSSL versions 0.9.7b or later, which contain patches addressing this vulnerability, and consider disabling RSA key exchange in favor of more secure alternatives such as Diffie-Hellman key exchange. Additionally, system administrators should monitor for unusual SSL/TLS connection patterns and implement proper key rotation procedures to minimize the impact if such attacks are successfully executed against vulnerable systems.