CVE-2024-41206

Executive Summary

CVE-2024-41206 is a stack-based buffer over-read vulnerability in tsMuxer, a popular tool for multiplexing and demultiplexing MPEG-TS streams. The flaw exists in the nightly build version nightly-2024-03-14-01-51-12 and allows an attacker to cause information disclosure by crafting a malicious TS video file. The vulnerability is triggered when tsMuxer processes a specially crafted TS file, leading to a read beyond the bounds of a stack buffer. This can leak sensitive memory contents, potentially exposing credentials, encryption keys, or other confidential data. The vulnerability has a CVSS score of 0.0 (placeholder) and an EPSS score of 0.0%, indicating low exploitation likelihood at this time. No public exploit code or patch is currently available.

Supply Chain & Package Security

tsMuxer is not distributed via NPM, PyPI, Go, or Ruby registries. It is typically compiled from source or downloaded as a binary from the official GitHub repository. Users should verify the integrity of downloaded binaries and consider building from source to reduce supply chain risks.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (placeholder)
• Attack Vector: Local (requires user to open a malicious file)
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required (victim must open the crafted TS file)
• Scope: Unchanged
• Confidentiality Impact: High (information disclosure)
• Integrity Impact: None
• Availability Impact: None
• Threat Level: Medium (due to information disclosure potential)

Deep Dive & Mechanics

The vulnerability is a classic stack-based buffer over-read (CWE-125). In tsMuxer, when parsing a TS file, the program reads data into a fixed-size stack buffer without proper bounds checking. An attacker can craft a TS file with a malformed packet that causes the program to read beyond the allocated buffer, leaking adjacent stack memory. This memory may contain sensitive data such as file paths, environment variables, or other processed data.

The vulnerable code path is likely in the TS packet parsing routine, where a loop reads data from the file into a buffer but does not validate the length of the data before copying. The over-read occurs when the program attempts to read more bytes than the buffer can hold, causing it to read from the stack beyond the buffer's end.

Vulnerable vs. Patched Code

Since no patch is available, we can only describe the vulnerable code pattern.

Vulnerable Code (Conceptual):

void parse_ts_packet(uint8_t *packet, int length) {
    uint8_t buffer[188]; // Fixed-size buffer
    for (int i = 0; i < length; i++) {
        buffer[i] = packet[i]; // No bounds check
    }
}

Patched Code (Conceptual):

void parse_ts_packet(uint8_t *packet, int length) {
    uint8_t buffer[188];
    int copy_len = (length < 188) ? length : 188; // Bounds check
    for (int i = 0; i < copy_len; i++) {
        buffer[i] = packet[i];
    }
}

Exploitation & Lab Setup

Red Team

1. Crafting the Malicious TS File: Use a hex editor to modify a valid TS file. Overwrite a packet's payload with a large number of bytes (e.g., 256 bytes) to trigger the over-read.
2. Delivery: Send the crafted file via email, download link, or physical media.
3. Trigger: The victim opens the file with tsMuxer (e.g., tsMuxerGUI malicious.ts).
4. Information Leak: The program may output leaked memory to stdout, stderr, or a log file. Capture this output to extract sensitive data.

Example Command:

tsMuxerGUI malicious.ts

Blue Team

1. Detection: Monitor for tsMuxer processes reading unusually large TS files or crashing with segmentation faults.
2. Prevention: Restrict execution of tsMuxer to trusted users and sandbox the application.
3. Response: If a crash is detected, capture the core dump and analyze it for leaked data. Isolate the affected system.

Indicators of Compromise (IOCs)

• File Hashes (SHA256): (Placeholder - compute from actual malicious file)
• Process Name: tsMuxerGUI or tsMuxer
• Network Activity: None (local vulnerability)
• Log Entries: Segmentation fault or buffer over-read errors in system logs
• File Artifacts: Malicious TS files with abnormal packet sizes (>188 bytes)

Detection Engineering

YARA Rule

rule CVE_2024_41206_tsMuxer_Overread {
    meta:
        description = "Detects malicious TS files exploiting CVE-2024-41206"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-41206"
    strings:
        $ts_header = { 47 } // TS sync byte
        $large_packet = /.{189,}/ // Packet larger than 188 bytes
    condition:
        $ts_header at 0 and #large_packet > 0
}

Sigma Rule

title: CVE-2024-41206 tsMuxer Buffer Over-Read
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects tsMuxer crashes due to buffer over-read
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\tsMuxerGUI.exe'
        CommandLine|contains: '.ts'
    condition: selection
falsepositives:
    - Legitimate large TS files
level: medium

Suricata Rule

alert tcp any any -> any any (msg:"CVE-2024-41206 tsMuxer Buffer Over-Read"; flow:to_client; content:"|47|"; offset:0; depth:1; content:"|00 00 00 00|"; within:188; byte_test:1,>,188,0; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Avoid using tsMuxer nightly build nightly-2024-03-14-01-51-12. Roll back to a previous stable version if available.
2. Workaround: Do not open untrusted TS files with tsMuxer. Use alternative tools like FFmpeg for TS processing.
3. Long-term: Monitor the tsMuxer GitHub repository for patches. Apply the fix once released.
4. Compensating Controls: Run tsMuxer in a sandboxed environment (e.g., Docker, Firejail) to limit the impact of information disclosure.

Valters IT
DevSecOps & Cyber Threat Intelligence