CVE-2011-2167 in Dovecot
Summary
by MITRE
script-login in Dovecot 2.0.x before 2.0.13 does not follow the chroot configuration setting, which might allow remote authenticated users to conduct directory traversal attacks by leveraging a script.
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Analysis
by VulDB Data Team • 11/07/2021
The vulnerability identified as CVE-2011-2167 affects Dovecot email server software versions 2.0.x prior to 2.0.13, specifically within the script-login component. This issue represents a critical security flaw that undermines the intended security boundaries established through chroot configuration settings. The vulnerability arises from the script-login functionality failing to properly respect the chroot jail configuration that administrators implement to restrict the service's access to system resources and directories.
The technical flaw manifests when remote authenticated users exploit the script-login component to perform directory traversal attacks. Despite the chroot configuration being properly set to limit the service's access to specific directories, the script-login functionality ignores these restrictions and allows attackers to navigate beyond the designated chroot boundaries. This occurs because the script execution mechanism does not properly validate or sanitize file paths before processing them, enabling malicious users to craft requests that bypass the intended directory restrictions.
The operational impact of this vulnerability is significant as it provides authenticated attackers with unauthorized access to directories outside the intended chroot environment. Attackers can leverage this flaw to access sensitive system files, configuration data, or other resources that should remain isolated within the chroot jail. The vulnerability particularly affects environments where Dovecot is configured to use chroot for security isolation, as the protection mechanism becomes ineffective against this specific attack vector.
From a cybersecurity perspective, this vulnerability aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as directory traversal. The issue also maps to ATT&CK technique T1059.008, which covers the use of script-based commands and scripts for execution within compromised systems. Organizations running affected Dovecot versions face increased risk of privilege escalation and data exposure, particularly when the script-login functionality is enabled and configured for use by authenticated users.
The recommended mitigation involves upgrading to Dovecot version 2.0.13 or later, which includes fixes specifically addressing the chroot configuration handling in the script-login component. Administrators should also review their current chroot configurations and ensure that script execution capabilities are properly restricted. Additional protective measures include implementing network segmentation, monitoring for unusual script execution patterns, and conducting regular security audits of mail server configurations to identify and remediate similar vulnerabilities. Organizations should also consider implementing additional access controls and privilege restrictions for script execution components within their email infrastructure.