CVE-2014-5386 in HipHop Virtual Machine
Summary
by MITRE
The mcrypt_create_iv function in hphp/runtime/ext/mcrypt/ext_mcrypt.cpp in Facebook HipHop Virtual Machine (HHVM) before 3.3.0 does not seed the random number generator, which makes it easier for remote attackers to defeat cryptographic protection mechanisms by leveraging the use of a single initialization vector.
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Analysis
by VulDB Data Team • 04/10/2022
The vulnerability identified as CVE-2014-5386 resides within Facebook's HipHop Virtual Machine implementation, specifically affecting the mcrypt_create_iv function in the mcrypt extension. This flaw represents a critical weakness in cryptographic randomness implementation that directly impacts the security of encryption operations performed by HHVM-based applications. The issue stems from the function's failure to properly seed the random number generator, creating predictable cryptographic outputs that undermine the fundamental security assumptions of encryption mechanisms.
The technical root cause of this vulnerability lies in the improper initialization of the random number generation process within the mcrypt_create_iv function. When a random number generator lacks proper seeding, it typically produces predictable sequences of numbers, especially when the same initial conditions are used repeatedly. In cryptographic contexts, this predictability creates severe security implications as attackers can potentially reconstruct the random sequence used to generate initialization vectors, thereby compromising the confidentiality and integrity of encrypted data. The vulnerability specifically affects HHVM versions prior to 3.3.0, indicating that this was a known issue that required explicit patching to address.
The operational impact of this vulnerability extends beyond simple cryptographic weakness to encompass broader security implications for applications relying on HHVM's mcrypt functionality. Remote attackers can exploit this flaw to defeat cryptographic protection mechanisms by leveraging the predictable nature of the initialization vectors generated by the vulnerable function. This weakness particularly affects applications that use mcrypt for encryption operations, potentially allowing attackers to decrypt sensitive information, forge cryptographic signatures, or perform other malicious activities that rely on compromised randomness. The vulnerability aligns with CWE-330, which addresses the use of insufficiently random values in cryptographic contexts, and represents a clear violation of the principle that cryptographic operations require high-quality randomness to maintain security guarantees.
From an adversarial perspective, this vulnerability creates opportunities for attackers to perform cryptanalysis against encrypted communications or stored data. The predictable initialization vectors generated by the flawed function can be exploited through various techniques including known-plaintext attacks, statistical analysis, or pattern recognition methods that take advantage of the non-random nature of the generated values. The attack surface is particularly concerning in web applications where HHVM is used for encryption operations, as remote attackers can potentially compromise the entire cryptographic infrastructure of the application. This vulnerability maps to ATT&CK technique T1583.001, which involves the use of cryptographic keys or random values to bypass security controls, and demonstrates how fundamental implementation flaws can create systemic security weaknesses.
Mitigation strategies for this vulnerability require immediate patching of affected HHVM installations to version 3.3.0 or later, where the random number generator is properly seeded during initialization. Organizations should also conduct comprehensive audits of their HHVM-based applications to identify all usages of the mcrypt_create_iv function and assess the cryptographic impact of the vulnerability. Additional protective measures include implementing proper entropy sources for random number generation, monitoring for unusual cryptographic behavior patterns, and ensuring that all cryptographic operations within HHVM applications are validated against known security standards. Security teams should also consider implementing network-level monitoring to detect potential exploitation attempts targeting this specific vulnerability, as the predictable nature of the generated values may create detectable patterns in network traffic or application behavior.