Executive Summary

CVE-2019-25650 is a structured exception handler (SEH) buffer overflow vulnerability in River Past CamDo version 3.7.6. It occurs when a local attacker supplies a specially crafted malicious string in the Lame_enc.dll name field, causing an out-of-bounds write.

The exploit involves creating a payload with a 280-byte buffer, a Next SEH (NSEH) jump instruction, and an SEH handler address pointing to a pop-pop-ret gadget. This allows the attacker to overwrite the SEH and redirect execution flow to injected shellcode.

By triggering this overflow, the attacker can execute arbitrary code locally with the privileges of the vulnerable application, ultimately establishing a bind shell on TCP port 3110.

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Compliance Impact

CVE-2019-25650 allows local attackers to execute arbitrary code with high impact on confidentiality, integrity, and availability of the affected system. This can lead to unauthorized access, data breaches, and system compromise.

Such impacts can negatively affect compliance with common standards and regulations like GDPR and HIPAA, which require protection of sensitive data and system integrity. Exploitation of this vulnerability could result in violations of these regulations due to potential data exposure or loss of system control.

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Impact Analysis

This vulnerability allows a local attacker to execute arbitrary code on the affected system with the privileges of the River Past CamDo application.

Successful exploitation can lead to the attacker gaining control over the system by spawning a bind shell listening on TCP port 3110, which can be used to remotely execute commands.

The impact includes complete compromise of confidentiality, integrity, and availability of the affected system, as indicated by the high CVSS scores (v3.1 base score 8.4 and v4.0 base score 8.6).

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Detection Guidance

This vulnerability can be detected by checking if the River Past CamDo version 3.7.6 or earlier is installed and if the 'Lame_enc.dll' name field in the application's options menu can be manipulated.

A practical detection method involves attempting to reproduce the exploit locally by crafting a malicious payload with a 280-byte buffer, NSEH jump instruction, and SEH handler address, then injecting it into the 'Lame_enc.dll' name field to see if a bind shell is established on TCP port 3110.

While no specific network commands are provided, you can monitor your system for unexpected listening services on port 3110, which is used by the exploit's bind shell.

For example, on Windows, you can run the command: netstat -ano | findstr :3110 to check if the bind shell is active.

On Linux or other systems, use: netstat -an | grep 3110 or ss -an | grep 3110 to detect if the port is open and listening.

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Mitigation Strategies

Immediate mitigation steps include preventing local attackers from accessing the River Past CamDo application or its configuration options.

Restrict user permissions to ensure that unprivileged users cannot run or modify the application or its settings.

Monitor and block incoming or outgoing connections on TCP port 3110 to prevent or detect exploitation attempts involving the bind shell.

If possible, update to a fixed or patched version of River Past CamDo that addresses this SEH buffer overflow vulnerability.

As a temporary workaround, avoid using or modifying the 'Lame_enc.dll' name field in the application's options menu.

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