CVE-2019-19735 in YetiShare
Summary
by MITRE
class.userpeer.php in MFScripts YetiShare 3.5.2 through 4.5.3 uses an insecure method of creating password reset hashes (based only on microtime), which allows an attacker to guess the hash and set the password within a few hours by bruteforcing.
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Analysis
by VulDB Data Team • 03/18/2024
The vulnerability identified as CVE-2019-19735 resides within the class.userpeer.php file of MFScripts YetiShare version 3.5.2 through 4.5.3, representing a critical security flaw that undermines the system's password reset functionality. This weakness stems from the implementation of an insecure cryptographic approach that relies solely on microtime for generating password reset hashes, creating a predictable and exploitable mechanism that significantly weakens the authentication security posture of the affected system.
The technical flaw manifests through the use of microtime-based hash generation, which provides insufficient entropy for cryptographic security purposes. This approach fails to incorporate adequate randomness sources or cryptographic strength measures, making the generated hashes susceptible to brute force attacks within a limited time window. The vulnerability specifically targets the password reset mechanism, where attackers can predict or guess the reset hash values by leveraging the predictable nature of microtime-based generation, potentially allowing unauthorized access to user accounts. This weakness directly maps to CWE-338, which addresses the use of cryptographically weak pseudo-random number generators, and aligns with ATT&CK technique T1110.003 for credential access through brute force methods.
The operational impact of this vulnerability extends beyond simple account compromise, as successful exploitation enables attackers to reset passwords for arbitrary user accounts within a few hours of observation. This creates a window of opportunity for unauthorized access to sensitive user data and system resources, potentially leading to data breaches, privilege escalation, and further lateral movement within the affected environment. The timeframe for exploitation is particularly concerning as it allows attackers to perform multiple attempts within a short period, increasing the probability of successful hash guessing and account takeover. The vulnerability affects all versions within the specified range, indicating a widespread exposure across multiple releases of the software, which compounds the potential impact across various deployments.
Mitigation strategies should prioritize immediate implementation of cryptographic fixes that replace the microtime-based approach with properly randomized and cryptographically secure hash generation methods. Organizations should ensure that password reset tokens incorporate sufficient entropy through the use of cryptographically secure random number generators and implement proper token expiration mechanisms. Additionally, rate limiting and account lockout mechanisms should be deployed to prevent automated brute force attempts, while monitoring systems should be configured to detect unusual password reset activities. The remediation process must include thorough code review to identify similar insecure practices throughout the application and implementation of industry-standard security practices that align with NIST SP 800-63B guidelines for authentication and account management.