CVE-2011-2166 in Dovecot
Summary
by MITRE
script-login in Dovecot 2.0.x before 2.0.13 does not follow the user and group configuration settings, which might allow remote authenticated users to bypass intended access restrictions by leveraging a script.
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Analysis
by VulDB Data Team • 11/07/2021
The vulnerability identified as CVE-2011-2166 affects Dovecot email server versions 2.0.x prior to 2.0.13, specifically within the script-login component. This issue represents a critical authorization bypass flaw that undermines the security configuration mechanisms designed to control user access to email services. The vulnerability occurs when Dovecot's script-login functionality fails to properly respect the user and group configuration settings that administrators establish to restrict access permissions. This misconfiguration allows authenticated remote users to potentially escalate their privileges and access resources they should not be authorized to reach.
The technical flaw stems from improper implementation of privilege separation mechanisms within Dovecot's authentication framework. When users authenticate through script-login, the system should enforce the configured user and group settings to ensure that each authenticated user operates within their designated security boundaries. However, the vulnerability allows attackers to exploit a script execution path that bypasses these fundamental access control checks. This misimplementation creates a scenario where authenticated users can leverage the script functionality to gain unauthorized access to mailboxes or system resources beyond their intended permissions. The flaw operates at the intersection of privilege management and script execution, creating a pathway for unauthorized privilege escalation.
From an operational impact perspective, this vulnerability poses significant risks to email server security and data integrity. Remote authenticated users who can successfully exploit this vulnerability can potentially access other users' email accounts, read confidential messages, and perform unauthorized actions within the email system. The impact extends beyond simple data access, as the bypassed access controls may enable users to escalate their privileges further within the system. Organizations relying on Dovecot for email services face potential data breaches, privacy violations, and compliance issues when this vulnerability exists in their systems. The vulnerability is particularly dangerous because it requires only authenticated access, meaning that attackers who have already compromised legitimate user credentials can leverage this flaw to expand their access.
The security implications align with CWE-276, which addresses improper privileges, and can be mapped to ATT&CK technique T1078 for valid accounts and privilege escalation. Organizations should immediately implement the patch released by Dovecot for version 2.0.13 and subsequent releases to address this vulnerability. Additionally, administrators should review and verify their user and group configuration settings to ensure proper enforcement of access controls. System monitoring should be enhanced to detect unusual script execution patterns that might indicate exploitation attempts. Regular security audits of authentication mechanisms and privilege management configurations are essential to prevent similar vulnerabilities from emerging in other components of the email infrastructure. The remediation process should include comprehensive testing to ensure that the patch does not introduce regressions in legitimate script functionality while maintaining the integrity of access control mechanisms.