CVE-2015-0886 in Jbcrypt
Summary
by MITRE
Integer overflow in the crypt_raw method in the key-stretching implementation in jBCrypt before 0.4 makes it easier for remote attackers to determine cleartext values of password hashes via a brute-force attack against hashes associated with the maximum exponent.
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Analysis
by VulDB Data Team • 05/01/2022
The vulnerability described in CVE-2015-0886 represents a critical weakness in the jBCrypt password hashing implementation that affects systems relying on this library for secure credential storage. This integer overflow flaw exists within the crypt_raw method's key-stretching algorithm, specifically impacting the handling of exponent values during the hashing process. The vulnerability stems from improper bounds checking and arithmetic operations that fail to properly validate input parameters, creating a scenario where attackers can exploit mathematical overflow conditions to manipulate the hashing behavior.
The technical implementation of this vulnerability involves an integer overflow occurring in the key-stretching mechanism that determines how many iterations the hashing algorithm should perform. When the maximum exponent value is reached, the integer overflow causes the system to wrap around to a much smaller value, effectively reducing the computational complexity of the hash. This reduction in complexity means that attackers can perform brute-force attacks against the compromised hashes with significantly reduced computational effort compared to what would normally be required. The flaw specifically affects versions of jBCrypt prior to 0.4, indicating that this was a known issue that required specific patching to address the underlying arithmetic overflow conditions.
The operational impact of this vulnerability extends far beyond simple password cracking capabilities, as it fundamentally undermines the security assurances provided by the password hashing mechanism. Attackers can leverage this weakness to significantly reduce the time required to reverse-engineer password hashes, making systems vulnerable to credential compromise at an accelerated rate. This vulnerability directly impacts the security of applications that depend on jBCrypt for password storage, potentially exposing user credentials and sensitive authentication data. The reduced computational requirements for brute-force attacks mean that attackers can test exponentially more password combinations within the same timeframe, effectively nullifying the security benefits that should be provided by the key-stretching algorithm.
The security implications of this vulnerability align with several established threat frameworks including the ATT&CK matrix under credential access techniques, where adversaries can exploit weaknesses in cryptographic implementations to gain unauthorized access to systems. From a CWE perspective, this vulnerability maps to CWE-190 Integer Overflow or Wraparound, which specifically addresses the dangers of arithmetic operations that exceed the maximum representable value for the data type. The flaw also demonstrates characteristics consistent with CWE-310 Cryptographic Issues, as it weakens the cryptographic strength of the hashing implementation. Organizations utilizing affected versions of jBCrypt should immediately implement patch management procedures to upgrade to version 0.4 or later, which contains the necessary fixes to prevent integer overflow conditions. Additionally, system administrators should conduct comprehensive security assessments to identify any potentially compromised credentials and implement additional monitoring for suspicious authentication activities that might indicate exploitation attempts.
The mitigation strategy for this vulnerability requires immediate remediation through software updates, but also necessitates a broader security posture review. Organizations should verify that all systems using jBCrypt have been updated to versions that properly handle integer overflow conditions in the key-stretching algorithm. Security teams must also consider implementing additional layers of protection such as account lockout mechanisms, multi-factor authentication, and regular security scanning to detect potential exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper input validation and arithmetic boundary checking in cryptographic implementations, particularly when dealing with iterative hashing algorithms that rely on computationally intensive operations to provide security guarantees.