CVE-2022-0324: Exploring the Vulnerability in DHCPv6 Packet Parsing Code and Its Potential Impact on DHCP Relay and Docker Systems

Recently, a critical vulnerability (CVE-2022-0324) was discovered by Eugene Lim of GovTech Singapore, which potentially affects DHCPv6 packet parsing code. This vulnerability can be exploited by a remote attacker to craft a packet that could cause a buffer overflow in a memcpy call, leading to an out-of-bounds memory write that ultimately crashes dhcp6relay. Dhcp6relay is an essential process in DHCP relay systems, and if it fails, it could result in a shutdown of the dhcp relay docker. In this post, we will analyze the vulnerability, provide code snippets to demonstrate the issue, and discuss possible mitigating steps to address it.

The Vulnerability

CVE-2022-0324 is a vulnerability in the DHCPv6 packet parsing code that can be exploited by a remote attacker to trigger a buffer overflow in a memcpy call. This can result in an out-of-bounds memory write that causes the dhcp6relay process to crash, potentially shutting down the dhcp relay docker. The vulnerability was discovered by Eugene Lim of GovTech Singapore and published on [DATE].

Exploiting the vulnerability requires crafting a malicious DHCPv6 packet and sending it to the target system. The target then attempts to process this packet without proper bounds checking, eventually leading to a buffer overflow and a crash.

This code snippet demonstrates how the vulnerability can be exploited by an attacker

#include <string.h>
#include <netinet/ip6.h>

void dhcp_parse_options(const unsigned char* buf, size_t optlen) {
    // ...
    while (optlen >= 2) {
        unsigned int optcode = buf[];
        unsigned int optsize = buf[1];

        if (opt_size > optlen) {
            // Opt_size is greater than optlen, leading to a buffer overflow vulnerability
            memcpy(out_of_bounds_data, buf, opt_size);
    }
    // ...
}

In the above example, the opt_size variable can end up being larger than the optlen variable.

Below are the original references to the discovered vulnerability

1. Official CVE-2022-0324 Vulnerability Details
2. Eugene Lim's Blog Post on the Discovery

Configure your local security policies to block unknown or unauthorized DHCPv6 packets.

3. Enable automated security updates in your operating system to ensure that you are always using the latest software.
4. Subscribe to mailing lists and security bulletins for alerts on potential vulnerabilities and exploits.

In Conclusion

CVE-2022-0324 is a critical vulnerability in DHCPv6 packet parsing code, discovered by Eugene Lim of GovTech Singapore. Attackers can exploit this vulnerability to cause a buffer overflow in memcpy, leading to an out-of-bounds write and causing dhcp6relay to crash. This, in turn, could lead to a shutdown of the dhcp relay docker, with potentially serious consequences for affected systems. Mitigation strategies include updating your software, securing your local environment, and keeping informed about emerging threats.

Timeline

Published on: 11/14/2022 17:15:00 UTC
Last modified on: 11/17/2022 23:16:00 UTC