CVE-2007-3108 in OpenSSL
Summary
by MITRE
The BN_from_montgomery function in crypto/bn/bn_mont.c in OpenSSL 0.9.8e and earlier does not properly perform Montgomery multiplication, which might allow local users to conduct a side-channel attack and retrieve RSA private keys.
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Analysis
by VulDB Data Team • 01/13/2025
The vulnerability identified as CVE-2007-3108 resides within the OpenSSL cryptographic library version 0.9.8e and earlier, specifically within the BN_from_montgomery function located in the crypto/bn/bn_mont.c file. This flaw represents a critical weakness in the implementation of Montgomery multiplication, a fundamental algorithm used in elliptic curve cryptography and RSA operations. The vulnerability arises from improper handling of the Montgomery reduction process, which is essential for efficient modular arithmetic in cryptographic computations.
The technical flaw manifests as a side-channel attack vector that exploits timing variations and power consumption patterns during cryptographic operations. When the BN_from_montgomery function fails to properly execute Montgomery multiplication, it creates observable differences in execution time that can be measured and analyzed by local attackers. This timing leakage occurs because the function does not perform constant-time operations, allowing adversaries to infer information about the secret RSA private key through careful measurement of computational delays. The vulnerability specifically impacts the Montgomery reduction algorithm which is used extensively in RSA decryption and signature operations, making it particularly dangerous for systems relying on RSA-based security.
From an operational perspective, this vulnerability presents a significant risk to systems running vulnerable OpenSSL versions, as local attackers with access to the system can potentially extract RSA private keys through sophisticated side-channel analysis techniques. The attack requires only local access to the system, making it more accessible than many other cryptographic attacks that require network-based exploitation. Once successful, the compromise of RSA private keys can lead to complete system compromise, as attackers can forge digital signatures, decrypt sensitive communications, and impersonate legitimate services. The impact extends beyond individual systems to potentially affect entire cryptographic infrastructures that depend on RSA key pairs.
The vulnerability maps to CWE-310, which specifically addresses cryptographic weaknesses related to side-channel attacks, and aligns with ATT&CK technique T1552.004 for unsecured credentials. Organizations should immediately upgrade to OpenSSL versions 0.9.8f or later where this vulnerability has been patched. Additional mitigations include implementing constant-time algorithm implementations, monitoring system access logs for suspicious activity, and conducting regular security assessments. System administrators should also consider deploying intrusion detection systems to monitor for potential side-channel attack patterns and ensure that cryptographic operations are properly isolated from potential attackers. The patch addresses the underlying implementation issue by ensuring that Montgomery multiplication operations execute in constant time regardless of input values, thereby eliminating the timing variations that enabled the side-channel attack.