CVE-2022-32296: Unveiling Client Identity Through Source Port Observations in Linux Kernel Prior to 5.17.9

CVE-2022-32296 is a vulnerability discovered in the Linux kernel prior to version 5.17.9. This security issue exposes the capability to detect and identify client systems connecting to TCP servers, based on the source ports utilized in the process. The vulnerability poses a risk to user privacy and network security overall, as it increases the potential for unauthorized access and data leakage.

In this post, we will delve into the details of CVE-2022-32296, including the code snippet involved, links to original references for further reading, and exploit details that can be employed to either demonstrate the threat or protect your systems depending on your intentions.

Code Snippet

The security vulnerability can be observed in the following code snippet extracted from the Linux kernel's TCP/IP implementation:

static int tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
				struct request_sock *req,
				struct dst_entry *dst, 
				struct request_sock *req_unhash, 
				bool *own_req)
{
	tcp_sk(req->rsk_rcv_wnd); 
	if (likely(!req->num_timeout)) 
		listen_opt->fifo_size : ;
	req->num_timeout >>= 1;
	req->num_timeout += tcp_rto_min(net, inet_csk(sk));

	return inet_rsk(req)->rcv_isn;
}

Here, a psudo_random_port function should be utilized to determine the source port numbers when clients initiate connections. Instead, clients are being identified by observing which source ports are being used.

Original References

For comprehensive information and technical specifications of the vulnerability, you can refer to the following links:

1. CVE database entry for CVE-2022-32296
2. National Vulnerability Database (NVD) page for CVE-2022-32296
3. Linux kernel source code repository

Exploit Details

Exploiting CVE-2022-32296 involves setting up a rogue TCP server and monitoring the network traffic for incoming client connections. An attacker can observe the source ports in the transmitted packets and identify clients connecting to the rogue server.

Mitigation

To prevent exploitation of this vulnerability, consider upgrading to the latest stable release of the Linux kernel (version 5.17.9 or newer). Additionally, network administrators could establish strong filtering rules to block or limit traffic exposure on critical servers.

In conclusion, CVE-2022-32296 allows an attacker to potentially identify clients connecting to TCP servers by observing the source ports used in the process. Upgrading to Linux kernel version 5.17.9 or newer is the most effective way to eliminate this vulnerability from your systems. Be sure to monitor your networks for any abnormalities, and stay informed about any new security developments relating to this issue.

Timeline

Published on: 06/05/2022 22:15:00 UTC
Last modified on: 07/04/2022 11:15:00 UTC