CVE-2021-36095 in Community Edition
Summary
by MITRE • 09/06/2021
Malicious attacker is able to find out valid user logins by using the "lost password" feature. This issue affects: OTRS AG ((OTRS)) Community Edition version 6.0.1 and later versions. OTRS AG OTRS 7.0.x version 7.0.28 and prior versions.
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Analysis
by VulDB Data Team • 09/09/2021
This vulnerability represents a critical information disclosure flaw that undermines the authentication security model of the OTRS Community Edition platform. The issue stems from the implementation of the "lost password" functionality which inadvertently reveals whether a given email address corresponds to an existing user account within the system. This type of vulnerability falls under the category of account enumeration attacks and aligns with CWE-204, which specifically addresses information exposure through improper error handling. The flaw exists because the application provides different response messages depending on whether the email address exists in the user database, creating a clear signal that can be exploited by malicious actors.
The technical implementation of this vulnerability allows attackers to systematically test email addresses against the password recovery endpoint to identify valid user accounts within the OTRS system. When a valid email address is submitted, the application typically returns a success message indicating that a password reset email has been sent. However, when an invalid email address is submitted, the response may differ significantly, potentially indicating that no account exists for that email address. This differential response behavior creates a straightforward method for attackers to enumerate valid user accounts without requiring any prior authentication credentials. The vulnerability affects both version 6.0.1 and later of the Community Edition, as well as all versions of OTRS 7.0.x prior to 7.0.28, indicating this was a persistent flaw across multiple release lines.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with a critical reconnaissance step for subsequent attack phases. Once valid user accounts are identified, attackers can proceed with various exploitation techniques including credential stuffing attacks against the compromised accounts, social engineering campaigns leveraging the known valid email addresses, or even targeted phishing attacks. This vulnerability directly maps to the attack pattern described in the MITRE ATT&CK framework under T1078 Valid Accounts, where adversaries leverage valid accounts to maintain persistent access. The exposure of legitimate user email addresses also increases the risk of targeted attacks against specific individuals within the organization, as attackers can now identify which employees have access to the OTRS system and potentially use this information for more sophisticated social engineering operations.
The security implications of this vulnerability are particularly severe given that OTRS systems are commonly used for customer service and help desk management, often containing sensitive organizational data and communication. Attackers who successfully enumerate valid user accounts can then attempt to compromise individual accounts through password reuse attacks, as many users employ the same credentials across multiple systems. Organizations using affected OTRS versions should immediately implement mitigations including disabling or modifying the password recovery functionality, implementing rate limiting on password reset requests, and ensuring that all responses to password recovery attempts are consistent regardless of whether the email address exists in the system. Additionally, network-level controls such as intrusion detection systems should be configured to monitor for unusual patterns of password recovery requests that may indicate enumeration attempts. The vulnerability highlights the importance of consistent error handling and response design in authentication systems, as proper implementation should ensure that all authentication-related endpoints provide identical responses to prevent information leakage about system state.