CVE-2007-6598 in Dovecot
Summary
by MITRE
Dovecot before 1.0.10, with certain configuration options including use of %variables, does not properly maintain the LDAP+auth cache, which might allow remote authenticated users to login as a different user who has the same password.
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Analysis
by VulDB Data Team • 07/30/2021
The vulnerability described in CVE-2007-6598 affects Dovecot email server software versions prior to 1.0.10, specifically when certain configuration options are enabled including the use of %variables. This issue represents a significant authentication bypass flaw that exploits improper cache management within the LDAP authentication mechanism. The vulnerability stems from the server's failure to correctly maintain the LDAP+auth cache, creating a condition where authenticated users can potentially impersonate other users who share identical passwords. This type of flaw falls under the category of improper authentication handling and cache management issues that can lead to privilege escalation and unauthorized access to user accounts.
The technical implementation of this vulnerability occurs when Dovecot processes LDAP authentication requests with variable substitution enabled through %variables in configuration files. When the LDAP+auth cache is not properly maintained, the system fails to correctly invalidate or update cached authentication results for users who have the same password. This cache inconsistency allows an authenticated user to leverage the flawed cache state to gain access to accounts belonging to other users who happen to share the same password. The vulnerability specifically targets the interaction between Dovecot's authentication caching mechanism and LDAP directory services, creating a scenario where cached credentials can be reused inappropriately across different user contexts.
From an operational impact perspective, this vulnerability presents a serious security risk for organizations relying on Dovecot for email authentication with LDAP backends. Attackers who have already gained access to any user account on the system can exploit this flaw to move laterally within the organization by accessing other accounts that share identical passwords. This creates a potential for widespread unauthorized access to email accounts, potentially compromising sensitive communications, personal data, and business information. The vulnerability is particularly dangerous because it requires minimal additional privileges beyond initial authentication, making it an attractive target for attackers seeking to expand their access within a compromised environment.
The security implications of this vulnerability align with several CWE categories including CWE-287 Improper Authentication and CWE-200 Information Exposure. The flaw also maps to ATT&CK techniques such as T1078 Valid Accounts and T1566 Phishing, as it enables attackers to leverage legitimate user credentials to access additional accounts. Organizations using Dovecot with LDAP authentication should prioritize immediate patching to version 1.0.10 or later, which addresses the cache management issue. Additional mitigations include implementing strict password policies to prevent password reuse, monitoring authentication logs for suspicious activity, and configuring Dovecot with proper cache invalidation settings. Security teams should also consider implementing multi-factor authentication to reduce the impact of credential compromise and establish network segmentation to limit lateral movement capabilities.