CVE-2024-36432

Executive Summary

CVE-2024-36432 is a high-severity arbitrary memory write vulnerability affecting specific Supermicro motherboard models (X11DPG-HGX2, X11PDG-QT, X11PDG-OT, X11PDG-SN) with BIOS firmware versions prior to 4.4. The vulnerability allows an attacker to write arbitrary data to memory, potentially leading to system instability, denial of service, or further exploitation. With a CVSS score of 7.5, the vulnerability is remotely exploitable without authentication, making it a critical risk for exposed systems. No public proof-of-concept (PoC) or exploit code is currently available, and the EPSS score is 0.0%, indicating low exploitation activity in the wild. However, the lack of a patch for some models and the potential for memory corruption necessitate immediate attention.

CVSS Breakdown & Threat Level

• CVSS Score: 7.5 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
• Attack Vector: Network (AV:N) – Exploitable remotely.
• 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) – Impact confined to the vulnerable component.
• Confidentiality Impact: None (C:N) – No data exposure.
• Integrity Impact: None (I:N) – No data modification.
• Availability Impact: High (A:H) – Potential for system crash or denial of service.

Threat Level: High. The vulnerability is remotely exploitable with low complexity and no authentication, making it a prime target for attackers seeking to disrupt operations or gain a foothold in critical infrastructure.

Deep Dive & Mechanics

The vulnerability resides in the BIOS firmware of Supermicro X11DPG-HGX2, X11PDG-QT, X11PDG-OT, and X11PDG-SN motherboards. It is classified as CWE-787 (Out-of-bounds Write), which occurs when software writes data beyond the bounds of an allocated memory buffer. In this case, the BIOS firmware fails to properly validate input or memory boundaries during certain operations, allowing an attacker to write arbitrary data to arbitrary memory locations.

The attack vector is network-based, meaning an attacker can send specially crafted packets to the motherboard's management interface (likely IPMI or BMC) to trigger the vulnerability. Since no authentication is required, the attacker can exploit the flaw without valid credentials. The impact is primarily on availability, as arbitrary memory writes can corrupt critical system structures, leading to system crashes, hangs, or unpredictable behavior. However, in some scenarios, memory corruption could be leveraged for privilege escalation or code execution, though this is not confirmed.

The vulnerability affects BIOS firmware versions before 4.4. The patch (version 4.4) likely includes input validation and bounds checking to prevent the out-of-bounds write. Without the patch, systems remain exposed.

Vulnerable vs. Patched Code

No specific code snippets are available for this vulnerability. However, based on the CWE-787 classification, the vulnerable code likely involves a memory copy or write operation without proper bounds checking. For example:

Vulnerable (pseudo-code):

void process_packet(char *input, size_t len) {
    char buffer[256];
    memcpy(buffer, input, len); // No bounds check on len
}

Patched (pseudo-code):

void process_packet(char *input, size_t len) {
    char buffer[256];
    if (len > sizeof(buffer)) {
        // Handle error
        return;
    }
    memcpy(buffer, input, len);
}

The patch ensures that the length of the input does not exceed the buffer size, preventing out-of-bounds writes.

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

• Target: Supermicro X11DPG-HGX2 motherboard with BIOS firmware version 4.2.
• Attacker: Kali Linux machine on the same network.
• Tools: Nmap, Metasploit (if module available), custom Python script for fuzzing.

Exploitation Steps:

1. Reconnaissance: Scan the target's IPMI/BMC interface (default port 623/UDP for IPMI).

   nmap -sU -p 623 <target_ip>
   

2. Fuzzing: Use a custom script to send malformed packets to the BMC to trigger the vulnerability.

   import socket
   import struct
   
   target_ip = "192.168.1.100"
   port = 623
   
   # Craft a malformed packet (example)
   packet = b"\x00" * 1000  # Oversized payload
   
   sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
   sock.sendto(packet, (target_ip, port))
   sock.close()
   

3. Exploit: If a public exploit becomes available, use it to crash the system or gain control. Currently, no exploit is public.

Note: Since no PoC is available, this is a theoretical approach. Always obtain proper authorization before testing.

Blue Team (Defensive)

Detection:

• Monitor for unusual network traffic to port 623/UDP (IPMI).
• Look for oversized or malformed packets targeting the BMC.
• Use IDS/IPS rules to alert on anomalous IPMI traffic.

Mitigation:

• Isolate management interfaces on a separate VLAN.
• Restrict access to the BMC via firewall rules.
• Apply the BIOS firmware patch (version 4.4) as soon as possible.

Indicators of Compromise (IOCs)

• Network: Unusual traffic to UDP port 623 (IPMI) from unknown sources.
• System: Unexpected system crashes or reboots without clear cause.
• Logs: IPMI logs showing failed authentication attempts or malformed packet errors.
• Memory: Corrupted memory regions in the BIOS firmware (requires forensic analysis).

Detection Engineering

YARA Rule

rule CVE_2024_36432_Supermicro_BIOS {
    meta:
        description = "Detects potential exploitation of CVE-2024-36432 in Supermicro BIOS"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-36432"
    strings:
        $s1 = "X11DPG-HGX2" ascii wide nocase
        $s2 = "X11PDG-QT" ascii wide nocase
        $s3 = "X11PDG-OT" ascii wide nocase
        $s4 = "X11PDG-SN" ascii wide nocase
        $s5 = "BIOS" ascii wide nocase
    condition:
        any of ($s1, $s2, $s3, $s4) and $s5
}

Sigma Rule

title: CVE-2024-36432 Supermicro BIOS Arbitrary Memory Write
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects network traffic targeting Supermicro BMC interfaces potentially exploiting CVE-2024-36432
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2024-36432
logsource:
    category: network
    product: suricata
detection:
    selection:
        dest_port: 623
        protocol: udp
        payload_length: "> 512"  # Oversized packets
    condition: selection
falsepositives:
    - Legitimate IPMI management traffic
level: high

Suricata Rule

alert udp any any -> any 623 (msg:"CVE-2024-36432 Supermicro BIOS Arbitrary Memory Write"; content:"|00|"; depth:1; offset:0; dsize:>512; classtype:attempted-dos; sid:1000001; rev:1;)

Remediation & Mitigation

1. Patch: Update BIOS firmware to version 4.4 or later for affected models. Check Supermicro's support site for the latest firmware.
2. Network Segmentation: Isolate management interfaces (IPMI/BMC) on a separate VLAN with strict access controls.
3. Firewall Rules: Block access to UDP port 623 from untrusted networks.
4. Monitoring: Enable logging on BMC and monitor for anomalous traffic.
5. Incident Response: If exploitation is suspected, isolate the system, collect logs, and perform forensic analysis.

Valters IT
Securing Digital Frontiers