How to remediate – WorldMail IMAP Server Traversal Arbitrary Mail Spool Access

1. Introduction

The WorldMail IMAP Server Traversal Arbitrary Mail Spool Access vulnerability affects Eudora WorldMail, a mail server for Windows. This flaw allows authenticated attackers to access other users’ messages and manage folders on the system. Successful exploitation could lead to sensitive information disclosure and potential instability of the affected host. The impact is likely to be medium in terms of confidentiality, integrity, and availability.

2. Technical Explanation

The Eudora WorldMail IMAP server does not properly filter directory traversal sequences within mailbox names or restrict access to mailboxes. This allows an attacker with valid credentials to navigate outside the intended user’s mailbox directory and access other users’ data, or manipulate system folders. The vulnerability is tracked as CVE-2005-3189.

• Root cause: Missing input validation on mailbox names when handling IMAP requests.
• Exploit mechanism: An attacker sends specially crafted IMAP commands containing directory traversal characters (e.g., “..”) to access files and directories outside their assigned mailbox. For example, an attacker could use a command like “SELECT “…/../../otheruser” to attempt to access another user’s mailbox.
• Scope: Affected products are Eudora WorldMail versions prior to a currently unknown patch.

3. Detection and Assessment

Confirming vulnerability requires checking the version of WorldMail installed on systems. A thorough assessment involves attempting to access other user mailboxes.

• Quick checks: Use the Windows “Program Files” directory or the registry (e.g., reg query HKLMSOFTWAREEudora) to identify the WorldMail version.
• Scanning: Nessus plugin ID d69b5a45 can detect this vulnerability, but results should be verified manually.
• Logs and evidence: Examine WorldMail IMAP server logs for failed or unusual access attempts involving directory traversal characters in mailbox names. Log file locations vary depending on the installation configuration.

reg query HKLMSOFTWAREEudora /v Version

4. Solution / Remediation Steps

Currently, there is no known patch available for this vulnerability. The following steps outline a risk mitigation approach.

4.1 Preparation

• No services need to be stopped, but monitor server performance closely during testing.
• Roll back plan: Restore from backup or revert the system snapshot if issues arise. A change window may be needed depending on business impact.

4.2 Implementation

1. Step 1: Implement strict access controls to limit user privileges to only their assigned mailboxes. This is a temporary mitigation until a patch becomes available.
2. Step 2: Monitor WorldMail logs for any suspicious activity, particularly attempts to access unauthorized mailboxes.
3. Step 3: Consider disabling IMAP if it’s not essential and alternative protocols are available.

4.3 Config or Code Example

Before

# No specific access controls configured - all authenticated users can potentially access any mailbox.

After

# Configure WorldMail with user-specific permissions to restrict access to only their assigned mailboxes. (Configuration details vary depending on the version of WorldMail.) 

4.4 Security Practices Relevant to This Vulnerability

List only practices that directly address this vulnerability type. Use neutral wording and examples instead of fixed advice.

• Practice 1: Least privilege – restrict user access rights to the minimum necessary for their role, reducing the impact if an account is compromised.
• Practice 2: Input validation – carefully validate all user-supplied input, including mailbox names, to prevent directory traversal attacks.

4.5 Automation (Optional)

No automation scripts are available due to the lack of a patch and version specific configuration requirements.

5. Verification / Validation

• Post-fix check: Verify that users can only access their assigned mailboxes through the IMAP interface.
• Re-test: Attempt to access other user’s mailboxes using directory traversal commands (e.g., “SELECT “…/../../otheruser”). Access should be denied.
• Smoke test: Confirm that legitimate email sending and receiving functionality remains operational for all users.
• Monitoring: Monitor WorldMail logs for failed access attempts to unauthorized mailboxes, indicating potential exploitation attempts.

# Attempt to access another user's mailbox using IMAP commands - should result in an error message.

6. Preventive Measures and Monitoring

Update security baselines and consider adding input validation checks during deployment.

• Baselines: Update security baselines or policies to require strict access controls for mail servers.
• Pipelines: Implement static analysis tools (SAST) in the CI/CD pipeline to identify potential input validation vulnerabilities in custom code.
• Asset and patch process: Establish a regular patch review cycle for all server software, including email servers.

7. Risks, Side Effects, and Roll Back

Implementing strict access controls may disrupt existing workflows if users previously had broader access privileges.

• Risk or side effect 1: Users may experience limited functionality if their access is overly restricted. Monitor user feedback and adjust permissions accordingly.
• Roll back: Restore the WorldMail configuration from backup if issues arise, reverting to the previous access control settings.

8. References and Resources

Link only to sources that match this exact vulnerability.

• Vendor advisory or bulletin: No official vendor advisory is currently available.
• NVD or CVE entry: CVE-2005-3189
• Product or platform documentation relevant to the fix: Refer to Eudora WorldMail documentation for access control configuration details (version specific).