CVE-2020-37192: MSN Password Recovery XXE Vulnerability

CVE-2020-37192 Overview

MSN Password Recovery version 1.30 contains an XML External Entity (XXE) injection vulnerability that allows attackers to read local system files through crafted XML input. Attackers can exploit the 'Favorites' tab by injecting a malicious XML file that references external entities to retrieve sensitive system configuration information.

Critical Impact

Local attackers can leverage this XXE vulnerability to exfiltrate sensitive system files, potentially exposing credentials, configuration data, and other confidential information stored on the affected system.

Affected Products

• MSN Password Recovery 1.30

Discovery Timeline

• 2026-02-11 - CVE-2020-37192 published to NVD
• 2026-02-12 - Last updated in NVD database

Technical Details for CVE-2020-37192

Vulnerability Analysis

This vulnerability is classified as CWE-611 (Improper Restriction of XML External Entity Reference). The XML parser in MSN Password Recovery fails to properly restrict external entity references when processing XML input through the 'Favorites' tab functionality. This oversight allows an attacker to craft malicious XML documents that include external entity declarations, which the parser will resolve and include in the document content.

The local attack vector requires user interaction, as the victim must load or import a malicious XML file. Once processed, the attacker-controlled XML can reference local system files using file:// URI schemes or other protocols supported by the underlying XML parser.

Root Cause

The root cause of this vulnerability lies in the insecure configuration of the XML parser used by MSN Password Recovery. The application does not disable external entity processing or Document Type Definition (DTD) processing when parsing XML files from the 'Favorites' feature. This allows external entities defined in the XML document's DTD to be resolved, leading to unauthorized file access.

Attack Vector

The attack requires local access to the target system and user interaction. An attacker must craft a malicious XML file containing XXE payloads and convince the user to load this file through the 'Favorites' tab in MSN Password Recovery. When the application processes the malicious XML, external entity references are resolved, causing the contents of specified local files to be included in the parsed document. This data can then be exfiltrated through various techniques such as out-of-band data extraction or error-based extraction.

The vulnerability mechanism involves injecting malicious XML that includes external entity declarations targeting sensitive files such as configuration files, credential stores, or system information. When the XML parser processes these entities, it reads the file contents and incorporates them into the document, making them accessible to the attacker. For detailed technical information, see the Exploit-DB #47896 entry and the VulnCheck Advisory.

Detection Methods for CVE-2020-37192

Indicators of Compromise

• Presence of unexpected XML files in user directories or application data folders containing DTD declarations with ENTITY references
• MSN Password Recovery accessing files outside its normal operational scope (e.g., system configuration files, hosts file, sensitive user data)
• XML files imported into the application containing suspicious DOCTYPE declarations or external entity definitions

Detection Strategies

• Monitor file system access patterns for MSN Password Recovery process accessing sensitive system files it would not normally require
• Implement endpoint detection rules to identify XML files containing common XXE payload patterns such as <!ENTITY declarations with SYSTEM or PUBLIC identifiers
• Configure application whitelisting to alert on unusual file access by MSN Password Recovery executables

Monitoring Recommendations

• Enable detailed file access auditing on sensitive directories and system files
• Deploy endpoint detection and response (EDR) solutions to monitor process behavior and file access patterns
• Implement user awareness training regarding the risks of importing untrusted XML files into applications

How to Mitigate CVE-2020-37192

Immediate Actions Required

• Avoid importing XML files from untrusted or unknown sources into MSN Password Recovery
• Consider discontinuing use of MSN Password Recovery 1.30 until a patched version is available
• Implement application sandboxing to limit the application's access to sensitive system files
• Monitor the Top Password website for security updates

Patch Information

No vendor patch information is currently available for this vulnerability. Organizations should monitor the vendor's official website and security advisories for updates. In the absence of an official patch, implementing the recommended workarounds and limiting the application's use is strongly advised.

Workarounds

• Do not import or load XML files from untrusted sources through the 'Favorites' functionality
• If possible, use an alternative password recovery tool that does not exhibit this vulnerability
• Restrict file system permissions to limit the application's ability to read sensitive system files
• Consider running the application in a sandboxed environment or virtual machine to contain potential exploitation

# Example: Restrict application permissions (Windows)
# Use Software Restriction Policies or AppLocker to limit file access
# icacls command to restrict read access to sensitive files for the application user
icacls C:\Windows\System32\config /deny "Users:(R)"