CVE-2019-19805 in YetiShare
Summary
by MITRE
_account_forgot_password.ajax.php in MFScripts YetiShare 3.5.2 through 4.5.3 takes a different amount of time to return depending on whether an email address is configured for the account name provided. This can be used by an attacker to enumerate accounts by guessing email addresses.
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Analysis
by VulDB Data Team • 03/18/2024
This vulnerability exists in the account_forgot_password.ajax.php component of MFScripts YetiShare versions 3.5.2 through 4.5.3, representing a timing attack against the password reset functionality. The flaw stems from inconsistent response times when processing account enumeration requests, where the system returns different processing durations based on whether a valid email address is associated with the provided account name. This timing variation creates a side-channel information leak that allows attackers to determine the existence of specific accounts through careful analysis of response delays.
The technical implementation of this vulnerability demonstrates a classic timing side-channel attack pattern that violates the principle of constant-time execution for security-critical operations. When an attacker submits a username or email address to the password reset endpoint, the system's response time varies significantly depending on whether the input corresponds to an existing account. This behavior directly maps to CWE-203, which describes the disclosure of information through timing variations, and represents a failure to implement consistent-time operations for authentication checks.
From an operational impact perspective, this vulnerability enables account enumeration attacks that can lead to unauthorized account discovery and subsequent exploitation attempts. Attackers can systematically test email addresses against the password reset functionality, identifying valid accounts within the system that can then be targeted through password spraying, credential stuffing, or other account compromise techniques. The vulnerability particularly affects systems where email addresses serve as primary account identifiers, creating a significant risk for user account compromise and potential data breaches.
The attack vector operates through a methodical process of sending multiple password reset requests with varying email addresses and measuring response times to distinguish between valid and invalid accounts. This technique aligns with ATT&CK tactic TA0001 (Initial Access) and technique T1566 (Phishing), as it enables attackers to gather intelligence about valid user accounts before launching more sophisticated attacks. The vulnerability also intersects with ATT&CK technique T1078 (Valid Accounts) since successful enumeration can lead to unauthorized access using discovered credentials.
Mitigation strategies should focus on implementing constant-time response handling for all authentication-related operations, ensuring that the system responds with consistent timing regardless of whether an account exists. Organizations should apply the latest security patches from MFScripts, implement rate limiting on password reset requests, and consider additional security controls such as CAPTCHA mechanisms to prevent automated enumeration attempts. The fix should ensure that all account validation operations execute in constant time, eliminating the timing variations that enable this attack. Additionally, implementing proper input validation and account lockout mechanisms can further reduce the risk of successful enumeration attacks.