CVE-2006-0818 in Mail Server
Summary
by MITRE
Absolute path directory traversal vulnerability in (1) MERAK Mail Server for Windows 8.3.8r with before IceWarp Web Mail 5.6.1 and (2) VisNetic MailServer before 8.5.0.5 allows remote authenticated users to include arbitrary files via a modified language parameter and a full Windows or UNC pathname in the lang_settings parameter to mail/index.html, which is not properly sanitized by the validatefolder PHP function, possibly due to an incomplete fix for CVE-2005-4558.
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Analysis
by VulDB Data Team • 07/12/2021
This vulnerability represents a critical directory traversal flaw in email server software that enables authenticated remote attackers to execute arbitrary file inclusion attacks. The issue affects MERAK Mail Server for Windows versions up to 8.3.8r and VisNetic MailServer versions prior to 8.5.0.5, specifically targeting the IceWarp Web Mail component. The vulnerability stems from improper input validation within the validatefolder PHP function, which fails to adequately sanitize the lang_settings parameter in the mail/index.html endpoint. Attackers can exploit this weakness by crafting malicious requests that include full Windows or UNC pathnames in the language parameter, effectively bypassing normal access controls and potentially gaining unauthorized access to sensitive system files.
The technical exploitation occurs through a carefully crafted modification of the language parameter that allows attackers to traverse directory structures and include arbitrary files from the server filesystem. This vulnerability is particularly dangerous because it operates within the web interface of email servers, which typically have elevated privileges and access to system resources. The flaw demonstrates incomplete remediation of a previous vulnerability CVE-2005-4558, indicating that security patches were not comprehensive enough to address all potential attack vectors. The validatefolder PHP function's inadequate sanitization creates a pathway for attackers to access files that should remain protected, potentially exposing configuration files, user data, or system binaries that could be used for further exploitation.
From an operational perspective, this vulnerability compromises the integrity and confidentiality of email server deployments by allowing unauthorized file access that could lead to data breaches, system compromise, or privilege escalation. The impact extends beyond simple information disclosure as attackers could potentially execute malicious code through included files or gain access to administrative functions. Organizations running affected versions of these email server solutions face significant risk of unauthorized access to their email infrastructure, potentially affecting thousands of user accounts and sensitive communications. The vulnerability's authentication requirement does not mitigate the risk substantially since email servers often have numerous legitimate users, and the attack surface remains broad enough to allow exploitation through compromised accounts or social engineering.
Security mitigations for this vulnerability should focus on implementing comprehensive input validation and sanitization measures within the affected PHP functions. Organizations should immediately update to patched versions of the affected software, specifically upgrading to IceWarp Web Mail 5.6.1 or later and VisNetic MailServer 8.5.0.5 or higher. Network segmentation and access controls should be implemented to limit exposure of the vulnerable web interface to untrusted networks. Additionally, implementing web application firewalls and monitoring for suspicious requests containing absolute paths or unusual parameter combinations can help detect exploitation attempts. This vulnerability aligns with CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) and maps to ATT&CK technique T1566 (Phishing) and T1078 (Valid Accounts) as attackers may leverage compromised credentials to exploit this weakness. Organizations should also conduct thorough security assessments of their email infrastructure to identify similar vulnerabilities and ensure comprehensive patch management processes are in place to prevent future incidents.