CVE-2016-5100 in Froxlor
Summary
by MITRE
Froxlor before 0.9.35 uses the PHP rand function for random number generation, which makes it easier for remote attackers to guess the password reset token by predicting a value.
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Analysis
by VulDB Data Team • 11/14/2022
The vulnerability identified as CVE-2016-5100 affects Froxlor versions prior to 0935 and represents a critical weakness in the application's cryptographic implementation. This flaw stems from the application's reliance on PHP's rand function for generating random numbers, specifically for password reset tokens. The rand function in PHP is known to be a linear congruential generator that produces predictable sequences when not properly seeded or when the seed is derived from predictable sources. This predictable behavior fundamentally compromises the security of the password reset mechanism, creating a significant attack surface for remote adversaries seeking to compromise user accounts.
The technical implementation of this vulnerability demonstrates a fundamental misunderstanding of cryptographic requirements within web applications. When Froxlor generates password reset tokens, it utilizes the rand function which does not provide cryptographically secure random numbers. This violates established security principles outlined in NIST SP 800-90A and CWE-330, which specifically address the use of insecure random number generators for security-critical operations. The predictable nature of the rand output means that an attacker who can observe or estimate the sequence can potentially calculate valid reset tokens for arbitrary user accounts, effectively bypassing the authentication protection mechanisms.
The operational impact of this vulnerability extends beyond simple account compromise, as it enables a range of sophisticated attacks within the broader context of the ATT&CK framework. An attacker could leverage this weakness to perform account takeover operations, credential stuffing attacks, or even establish persistent access through password reset mechanisms. The vulnerability aligns with ATT&CK technique T1566, which covers credential harvesting through social engineering and automated attacks, and T1078, which addresses legitimate credentials use. The ease of exploitation makes this particularly dangerous as it requires minimal technical sophistication while providing significant access privileges to the affected system.
Mitigation strategies for CVE-2016-5100 must address both immediate remediation and long-term architectural improvements. The primary solution involves upgrading to Froxlor version 0935 or later, which implements proper cryptographic random number generation using PHP's random_int or random_bytes functions. Organizations should also conduct comprehensive security assessments to identify other instances of insecure random number usage within their applications, as this represents a common pattern in legacy codebases. Additionally, implementing proper entropy sources and ensuring that all security-critical random number generation utilizes cryptographically secure methods aligns with industry best practices and helps prevent similar vulnerabilities from emerging in future implementations.