CVE-2020-37120: Rubo DICOM Viewer Buffer Overflow RCE Flaw

CVE-2020-37120 Overview

CVE-2020-37120 is a stack-based buffer overflow vulnerability affecting Rubo DICOM Viewer 2.0, a medical imaging software used for viewing DICOM (Digital Imaging and Communications in Medicine) files. The vulnerability exists in the DICOM server name input field, where insufficient bounds checking allows attackers to overflow the buffer and overwrite the Structured Exception Handler (SEH). By crafting a malicious text file with a carefully constructed payload, attackers can achieve arbitrary code execution on vulnerable systems.

Critical Impact

Successful exploitation of this vulnerability allows attackers to execute arbitrary code on systems running Rubo DICOM Viewer 2.0, potentially compromising medical imaging workstations and sensitive patient data.

Affected Products

• Rubo DICOM Viewer 2.0
• Systems importing malicious configuration files through the DICOM server name field

Discovery Timeline

• 2026-02-05 - CVE-2020-37120 published to NVD
• 2026-02-05 - Last updated in NVD database

Technical Details for CVE-2020-37120

Vulnerability Analysis

This vulnerability is classified as CWE-121 (Stack-based Buffer Overflow), a dangerous memory corruption issue that occurs when an application writes data beyond the boundaries of a stack-allocated buffer. In the case of Rubo DICOM Viewer 2.0, the application fails to properly validate the length of input provided in the DICOM server name field before copying it to a fixed-size buffer on the stack.

The attack requires local access and user interaction, as the victim must open or import a maliciously crafted file containing the exploit payload. When the oversized input is processed, it overwrites adjacent memory on the stack, including the Structured Exception Handler (SEH) chain. SEH overwrite is a classic Windows exploitation technique where attackers replace the exception handler pointer with addresses pointing to attacker-controlled code or ROP gadgets.

Root Cause

The root cause of this vulnerability is improper input validation in the DICOM server name processing functionality. The application allocates a fixed-size buffer on the stack to store the server name but does not enforce length restrictions on user-supplied input. This allows attackers to provide input exceeding the buffer's capacity, leading to a classic stack-based buffer overflow condition. The absence of modern exploit mitigations or their bypassability enables reliable SEH overwrite attacks.

Attack Vector

The attack vector for CVE-2020-37120 involves creating a specially crafted text file containing an oversized payload designed to trigger the buffer overflow. When a user opens or imports this malicious file using Rubo DICOM Viewer 2.0, the application processes the server name field without proper bounds checking.

The exploitation process involves overflowing the stack buffer with a carefully crafted payload that:

1. Fills the buffer with padding data
2. Overwrites the SEH chain with attacker-controlled addresses
3. Includes shellcode or ROP chain for code execution
4. Triggers an exception to invoke the corrupted exception handler

Technical details and proof-of-concept code are available through the Exploit-DB entry #48351. Additional technical information can be found in the VulnCheck Advisory.

Detection Methods for CVE-2020-37120

Indicators of Compromise

• Presence of unusually large text files or configuration files being opened by Rubo DICOM Viewer
• Application crashes or unexpected termination of dicom_viewer.exe processes
• Anomalous child processes spawned from Rubo DICOM Viewer application
• Evidence of shellcode execution patterns in memory analysis

Detection Strategies

• Monitor for Rubo DICOM Viewer 2.0 installations across the environment using asset inventory tools
• Implement application crash monitoring to detect potential exploitation attempts
• Deploy endpoint detection rules to identify SEH overwrite exploitation patterns
• Use file integrity monitoring on DICOM configuration directories for suspicious file additions

Monitoring Recommendations

• Enable Windows Application Event Log monitoring for application fault events from Rubo DICOM Viewer
• Configure SentinelOne to alert on suspicious memory access patterns and exception handling anomalies
• Monitor for unusual file operations involving the DICOM Viewer application
• Implement behavioral analysis for detecting code execution from stack memory regions

How to Mitigate CVE-2020-37120

Immediate Actions Required

• Discontinue use of Rubo DICOM Viewer 2.0 if possible, as the software appears to be discontinued
• Isolate systems running Rubo DICOM Viewer from network access where feasible
• Implement strict file import policies to prevent users from opening untrusted files
• Consider migrating to actively maintained DICOM viewing software with security support

Patch Information

No official vendor patch is available for this vulnerability. The Rubomedical website for DICOM Viewer is only accessible via the Wayback Archive, indicating the product may be abandoned. Organizations should prioritize migrating to alternative DICOM viewing solutions that receive active security updates and support.

Workarounds

• Restrict the application's ability to open files from untrusted sources using Windows Software Restriction Policies
• Implement application whitelisting to prevent execution of unauthorized code
• Deploy Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR) at the OS level if not already enabled
• Consider running the application in an isolated virtual environment to limit the impact of potential exploitation

Organizations using medical imaging software should ensure that endpoint protection solutions like SentinelOne Singularity are deployed and configured to detect and prevent buffer overflow exploitation attempts.