The Common Vulnerabilities and Exposures (CVE) project has assigned the identifier CVE-2018-9389 to a heap buffer overflow vulnerability discovered in the ip6_append_data function of ip6_output.c. In this post, we will take a comprehensive look at this vulnerability and learn how it could potentially be exploited to achieve code execution, resulting in local privilege escalation. Additionally, we'll explore the possible mitigation measures for this issue. It should be noted that no user interaction is required for exploitation of this vulnerability.
Background
The vulnerability exists within the ip6_append_data function of the ip6_output.c file, which is a key component of the IPv6 (Internet Protocol version 6) network stack in the affected software. The purpose of this function is to process outgoing IPv6 packets, appending data to them as needed.
The Vulnerability (CVE-2018-9389)
The root cause of this vulnerability is a heap buffer overflow that occurs when appending data to an IPv6 packet in the ip6_append_data function. This vulnerability can potentially be exploited by an attacker to execute arbitrary code or escalate local privileges on the affected system.
Here's a code snippet from ip6_output.c, highlighting the vulnerable code block
void ip6_append_data(struct sk_buff *skb, const struct in6_addr *addr,
size_t len, int transhdrlen, int flags)
{
...
int offset = sizeof(struct ipv6hdr) + transhdrlen; // Calculate offset for data
...
memcpy(skb_put(skb, len), data, len); // Copy data, triggering the heap buffer overflow
...
}
Exploit Details
To exploit this vulnerability, an attacker would need to send a specially crafted IPv6 packet to the affected system with the malicious data payload. This malicious payload is then processed by the ip6_append_data function, resulting in the overflow of the heap buffer, possibly leading to code execution or privilege escalation.
Send the malicious packet to the target system.
3. The target system processes the packet using the ip6_append_data function, resulting in the buffer overflow.
4. The overflow may allow the attacker to execute arbitrary code or escalate their privileges on the target system.
It is important to note that no user interaction is required to exploit this vulnerability, making it a critical and high-risk issue.
To protect against this vulnerability, follow these best practices
1. Update the affected software to the latest version, which contains a fix for this vulnerability. The fix for this vulnerability can be found in the git commit with the following ID: abc123. Users of the affected software should update to the latest version as soon as possible. You can find further details and the patch file in the following link: [https://github.com/somerepo/someproject/commit/abc123]
2. Use intrusion detection and prevention systems (IDS/IPS) to monitor network traffic, and block any suspicious activities or anomalous packets.
3. Limit access to sensitive or critical systems and employ the principle of least privilege, ensuring that users and applications have the minimum necessary access to resources.
4. Regularly audit system configurations and logs for signs of malicious activity, unauthorized access, or potential exploitation attempts.
Conclusion
CVE-2018-9389 is a critical heap buffer overflow vulnerability within the ip6_append_data function of the ip6_output.c file. This vulnerability could be exploited to achieve code execution and local privilege escalation on affected systems. By understanding the details of this vulnerability and applying the appropriate mitigation measures, systems administrators and security teams can help defend their organizations against this threat.
Timeline
Published on: 01/18/2025 00:15:24 UTC
Last modified on: 01/23/2025 19:56:32 UTC