CVE-2020-37187: SpotDialup DoS Vulnerability

CVE-2020-37187 Overview

CVE-2020-37187 is a denial of service vulnerability affecting SpotDialup version 1.6.7. The vulnerability exists in the registration name input field and allows attackers to crash the application by exploiting improper input validation. When a user pastes a specially crafted 1000-character buffer payload into the 'Name' field during registration, the application fails to properly handle the oversized input, resulting in an application crash.

Critical Impact

Attackers can cause denial of service by crashing the SpotDialup application through a buffer overflow in the registration name field, potentially disrupting dial-up connectivity management.

Affected Products

• SpotDialup 1.6.7

Discovery Timeline

• 2026-02-11 - CVE CVE-2020-37187 published to NVD
• 2026-02-12 - Last updated in NVD database

Technical Details for CVE-2020-37187

Vulnerability Analysis

This vulnerability is classified as CWE-120 (Buffer Copy without Checking Size of Input), a classic buffer overflow condition. The flaw occurs when the SpotDialup application accepts user input in the registration 'Name' field without implementing proper bounds checking. The application expects a reasonably sized string for the name field but fails to validate the length of user-supplied input before copying it into a fixed-size buffer.

When an attacker provides a 1000-character payload, the application attempts to store this data in a buffer that cannot accommodate such a large string. This results in memory corruption and subsequent application termination. The vulnerability requires local access and user interaction to exploit, as the attacker must either have direct access to the machine running SpotDialup or social engineer a user into pasting the malicious payload.

Root Cause

The root cause of CVE-2020-37187 is the absence of input length validation in the registration name processing routine. The application performs a buffer copy operation without first verifying that the source data fits within the destination buffer's allocated size. This is a fundamental secure coding violation where user-controlled input is trusted without sanitization.

Attack Vector

The attack vector requires local access to the system running SpotDialup 1.6.7. An attacker must generate a buffer payload consisting of approximately 1000 characters and paste this payload into the 'Name' input field within the application's registration interface. Upon submission or field processing, the oversized input triggers the buffer overflow condition, causing the application to crash.

The local attack vector and requirement for user interaction (either by the attacker directly or through social engineering) limits the exploitability of this vulnerability. However, in shared computing environments or scenarios where attackers have limited local access, this vulnerability could be used to disrupt dial-up connectivity services.

Detection Methods for CVE-2020-37187

Indicators of Compromise

• SpotDialup application crashes or unexpected terminations during registration attempts
• Windows Event Log entries indicating application faults in spotdialup.exe or related processes
• Unusually long strings (1000+ characters) found in application input fields or log files

Detection Strategies

• Monitor for repeated application crashes of SpotDialup through Windows Event Viewer
• Implement application whitelisting and monitoring to detect unauthorized interaction with SpotDialup
• Use endpoint detection and response (EDR) solutions to identify buffer overflow exploitation attempts

Monitoring Recommendations

• Configure SentinelOne agents to monitor for process crashes and memory corruption events in SpotDialup
• Enable application crash logging and review logs for patterns consistent with denial of service attempts
• Deploy file integrity monitoring on SpotDialup installation directories to detect tampering

How to Mitigate CVE-2020-37187

Immediate Actions Required

• Restrict access to systems running SpotDialup 1.6.7 to trusted users only
• Consider disabling or uninstalling SpotDialup if it is not essential for operations
• Implement application control policies to limit who can interact with the vulnerable application
• Monitor for exploitation attempts using endpoint security solutions

Patch Information

No vendor patch information is currently available for this vulnerability. The software vendor (NSAuditor) has not released a security advisory addressing this specific issue. Organizations should check the NSA Auditor Homepage for potential updates or patches. Additional technical details are available through the VulnCheck Security Advisory and Exploit-DB #47904.

Workarounds

• Limit physical and remote access to machines running the affected software
• Deploy network segmentation to isolate systems using legacy dial-up management tools
• Implement user training to prevent social engineering attacks that might trick users into pasting malicious payloads
• Consider migrating to alternative dial-up management solutions that are actively maintained

# Disable SpotDialup service if not required (Windows)
# Stop the application from running at startup
reg delete "HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run" /v SpotDialup /f

# Alternatively, restrict user access via NTFS permissions
icacls "C:\Program Files\SpotDialup" /deny Users:(OI)(CI)(RX)