CVE-2020-37191: Dialup Password Recovery DOS Vulnerability

CVE-2020-37191 Overview

CVE-2020-37191 is a denial of service vulnerability affecting Top Password Software Dialup Password Recovery version 1.30. The vulnerability allows attackers to crash the application by overflowing input fields with excessively large payloads. Specifically, attackers can trigger an application crash by inserting a large 5000-character payload into the User Name and Registration Code input fields, causing a buffer overflow condition.

Critical Impact

Local attackers can cause application denial of service by providing oversized input to the User Name and Registration Code fields, crashing the Dialup Password Recovery tool and disrupting password recovery operations.

Affected Products

• Top Password Software Dialup Password Recovery 1.30

Discovery Timeline

• 2026-02-11 - CVE CVE-2020-37191 published to NVD
• 2026-02-12 - Last updated in NVD database

Technical Details for CVE-2020-37191

Vulnerability Analysis

This vulnerability is classified as CWE-120 (Buffer Copy without Checking Size of Input), commonly known as a classic buffer overflow. The application fails to properly validate the length of user-supplied input before copying it into fixed-size memory buffers. When a user enters data into the User Name or Registration Code fields, the application does not enforce appropriate bounds checking, allowing attackers to submit input that exceeds the allocated buffer size.

The local attack vector requires an attacker to have access to the target system and interact with the application's user interface. The vulnerability requires user interaction, as the malicious input must be entered through the application's input fields. While the impact is limited to application availability (denial of service), this represents a failure in fundamental input validation practices.

Root Cause

The root cause is improper input validation in the registration dialog of Dialup Password Recovery 1.30. The application allocates fixed-size buffers for the User Name and Registration Code fields but does not implement adequate length checks before copying user-supplied data into these buffers. When input exceeding the buffer capacity (approximately 5000 characters) is provided, the overflow corrupts adjacent memory, leading to an application crash.

Attack Vector

The attack requires local access to a system running the vulnerable software. An attacker must launch the Dialup Password Recovery application and navigate to the registration interface. By entering approximately 5000 characters or more into either the User Name or Registration Code field and submitting the form, the attacker triggers the buffer overflow condition. This causes the application to crash, resulting in denial of service. The attack does not require authentication or elevated privileges, only physical or remote desktop access to interact with the application's GUI.

Technical details and proof-of-concept information are available in the Exploit-DB #47907 advisory. Additional information can be found in the VulnCheck Advisory on Top Password.

Detection Methods for CVE-2020-37191

Indicators of Compromise

• Unexpected crashes or termination of the DialupPasswordRecovery.exe process
• Windows Event Log entries indicating application crashes related to buffer overflow or access violations
• Multiple rapid restarts of the Dialup Password Recovery application

Detection Strategies

• Monitor for application crash events associated with Dialup Password Recovery using Windows Event Viewer
• Implement endpoint detection rules to alert on suspicious process termination patterns for password recovery utilities
• Deploy application crash monitoring to identify repeated denial of service attempts

Monitoring Recommendations

• Enable verbose logging for password recovery tool usage on workstations
• Configure SentinelOne Singularity to monitor for abnormal application behavior and crash patterns
• Review system event logs periodically for signs of buffer overflow exploitation attempts

How to Mitigate CVE-2020-37191

Immediate Actions Required

• Restrict access to the Dialup Password Recovery application to trusted administrative users only
• Consider uninstalling the vulnerable software if not actively required for business operations
• Implement application whitelisting to control which users can execute the tool

Patch Information

No vendor patch information is currently available. The vendor website can be found at Top Password Tool. Users should check for updated versions or contact the vendor directly for remediation guidance.

Workarounds

• Limit physical and remote access to systems where the vulnerable software is installed
• Use alternative password recovery tools that do not contain this vulnerability
• Implement endpoint protection solutions like SentinelOne to detect and prevent application crashes caused by exploitation attempts

# Restrict application access using Windows permissions
# Navigate to the application directory and limit execution rights
icacls "C:\Program Files\Top Password Software\Dialup Password Recovery" /inheritance:r /grant:r Administrators:F