CVE-2017-15361 in RSA Library
Summary
by MITRE
The Infineon RSA library 1.02.013 in Infineon Trusted Platform Module (TPM) firmware, such as versions before 0000000000000422 - 4.34, before 000000000000062b - 6.43, and before 0000000000008521 - 133.33, mishandles RSA key generation, which makes it easier for attackers to defeat various cryptographic protection mechanisms via targeted attacks, aka ROCA. Examples of affected technologies include BitLocker with TPM 1.2, YubiKey 4 PGP key generation, and the Cached User Data encryption feature in Chrome OS.
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Analysis
by VulDB Data Team • 12/27/2024
The vulnerability identified as CVE-2017-15361 represents a critical flaw in the Infineon RSA library version 1.02.013 embedded within Trusted Platform Module firmware implementations. This weakness manifests during the RSA key generation process, where the cryptographic library fails to properly randomize certain mathematical parameters that should remain unpredictable and unique for each generated key. The flaw affects multiple TPM firmware versions, specifically those before build numbers 0000000000000422 through 4.34, 000000000000062b through 6.43, and 0000000000008521 through 133.33, creating a widespread impact across numerous security-critical systems. The vulnerability has been categorized as ROCA (Return of Coppersmith's Attack) due to its reliance on mathematical techniques that allow attackers to factorize RSA moduli by exploiting predictable mathematical structures in the key generation algorithm. This weakness directly violates the fundamental cryptographic principle that RSA key generation must produce unpredictable and independent prime numbers that form the basis of secure encryption.
The technical implementation of this vulnerability stems from a flawed random number generation process within the RSA key generation routine, where certain parameters such as the prime factors used in key construction follow predictable mathematical sequences rather than true random distributions. This predictable pattern allows attackers to use mathematical algorithms to reverse-engineer the private keys from the corresponding public keys, effectively breaking the encryption that these systems are designed to provide. The flaw specifically impacts the generation of RSA-2048 and RSA-3072 bit keys, where the mathematical structure of the primes reveals patterns that make factorization computationally feasible for determined attackers. This issue creates a significant risk because the RSA key generation process should produce keys that are computationally infeasible to break through brute force or mathematical attacks, but instead produces keys with mathematical weaknesses that can be exploited using known factorization techniques.
The operational impact of CVE-2017-15361 extends across numerous security technologies that rely on TPM-based key generation and encryption mechanisms. Systems utilizing BitLocker encryption with TPM 1.2 are particularly vulnerable, as the encryption keys used to protect disk data can be recovered by attackers who exploit the predictable patterns in the RSA key generation process. Similarly, YubiKey 4 devices that generate PGP keys through the affected TPM firmware become compromised, potentially allowing attackers to decrypt communications or impersonate users. Chrome OS systems using Cached User Data encryption features are also at risk, as the encryption keys protecting user data can be reverse-engineered. The vulnerability affects both hardware security modules and software implementations that depend on the compromised TPM library, creating a cascading security risk that extends far beyond the immediate TPM implementations. Organizations using affected systems may experience unauthorized access to encrypted data, compromised digital signatures, and potential elevation of privileges through the exploitation of the mathematical weaknesses in the RSA key generation process.
Mitigation strategies for CVE-2017-15361 require immediate action to replace or upgrade affected TPM firmware versions to patched implementations that properly randomize the RSA key generation parameters. System administrators should conduct comprehensive inventory assessments to identify all affected devices, including hardware security modules, computers, and embedded systems that utilize the vulnerable Infineon TPM firmware. The remediation process involves updating firmware to versions that address the predictable random number generation issue, typically requiring a complete system reboot and firmware update procedure. Organizations must also consider reissuing cryptographic keys across all affected systems, as any keys generated using the vulnerable library should be considered compromised. Security teams should implement monitoring procedures to detect potential exploitation attempts and establish protocols for key rotation and system verification. The vulnerability demonstrates the critical importance of proper random number generation in cryptographic implementations and highlights the necessity of regular security audits of embedded firmware components. This issue aligns with CWE-330 (Use of Insufficiently Random Values) and represents a classic example of how mathematical weaknesses in cryptographic algorithms can be exploited through advanced cryptanalysis techniques, as documented in various ATT&CK framework categories related to credential access and privilege escalation through cryptographic weaknesses.