CVE-2023-23559: An In-Depth Analysis of Integer Overflow in the Linux Kernel's RNDIS_WLAN Driver

In the world of cybersecurity, the discovery of vulnerabilities in popular systems is an ongoing process, and among these, the Linux kernel is always a prime target. In this post, we will delve into the details of a recent vulnerability found in the Linux kernel, assigned to CVE-2023-23559. This vulnerability affects the RNDIS WLAN driver (drivers/net/wireless/rndis_wlan.c) in Linux kernel versions up to and including 6.1.5. The issue stems from an integer overflow in the addition operation within the rndis_query_oid function. The following sections will provide an overview of the affected code, the vulnerability's consequences, and mitigations to protect your Linux system.

Affected Code and Technical Analysis

The vulnerability, as mentioned before, lies in the "rndis_query_oid" function located in the "drivers/net/wireless/rndis_wlan.c" file of the Linux kernel. A code snippet of the affected function is provided below:

static int rndis_query_oid(struct usbnet *usbdev,
	u32 oid, void *buf, unsigned int len)
{
	struct rndis_wlan_private *priv = get_rndis_wlan_priv(usbdev);
...
   unsigned int copy_len;
...
   copy_len = min(priv->stats_len, skb->len);
   if (copy_len < req_len)
     n = -EOVERFLOW;
   else
     n = ;

   memcpy(buf, skb->data, copy_len);
...
}

In the code snippet above, the integer overflow vulnerability originates from the calculation of the copy_len value by using the min function. In the case where an attacker can control both priv->stats_len and skb->len values, they can manipulate these variables to force an overflow to occur in the addition operation. This, in turn, can cause undefined behavior and open a door for potential exploitation.

Exploit Details

The exploit itself would require an attacker to manipulate and control the values in the affected driver. Currently, there are no known active exploits in the wild targeting this specific CVE. However, given the substantial userbase and the sheer number of Linux-based systems deployed worldwide, a successful exploitation could potentially impact a large number of users and organizations.

Upon a successful exploit, an attacker might be able to leverage the undefined behavior to escalate privileges, access sensitive data, or execute arbitrary code on the target Linux system, leading to increased security risks.

Original References

The vulnerability was first discovered in the Linux kernel tree accessible through the following link:

- Linux kernel source: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/wireless/rndis_wlan.c?id=v6.1.5

The CVE-2023-23559 was assigned by MITRE

- CVE Details: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-23559

To protect your Linux system from this vulnerability, you should follow these recommendations

1. Regularly update your Linux kernel to the latest versions, as they often include security patches and bug fixes for known vulnerabilities.
2. Keep an eye on your Linux distribution's security advisories and apply recommended updates as soon as they become available.

Conclusion

CVE-2023-23559 highlights the importance of staying up-to-date with the latest security patches and keeping an eye on newly discovered Linux kernel vulnerabilities. As system administrators and users, we must remain vigilant and proactive in mitigating threats to keep our infrastructure and data secure.

Timeline

Published on: 01/13/2023 01:15:00 UTC
Last modified on: 03/02/2023 16:15:00 UTC