CVE-2024-55627: A Deep Dive into Suricata's Buffer Overflow Vulnerability <em>- Exploit Details, Code Snippets, and Patch Information</em>

Suricata, an open-source network Intrusion Detection System (IDS), Intrusion Prevention System (IPS), and Network Security Monitoring (NSM) engine, recently made headlines due to a critical vulnerability (CVE-2024-55627) discovered in versions prior to 7..8. This vulnerability can lead to a substantial buffer overflow while a specially crafted TCP stream is zero-filled during initialization with memset due to an unsigned integer underflow.

This blog post will explore the vulnerability in depth, from the initial discovery to mitigations and patches. We will also provide original references, code snippets, and exploit details to understand the inner workings behind this flaw.

Vulnerability details

The vulnerability CVE-2024-55627 pertains to a buffer overflow induced by an unsigned integer underflow in Suricata's TCP handling implementation. A threat actor can exploit this flaw by sending a specially crafted TCP stream to a vulnerable Suricata deployment.

A large buffer would be zero-filled during initialization with memset, exposing the affected system to potential security risks, including denial of service (DoS) attacks and arbitrary code execution.

Original References

The original disclosure for this vulnerability can be found in the following security advisory published by the Suricata project:

- Suricata Security Advisory 2024-01

The advisory states that Suricata version 7..8 addresses the issue and provides a link to the relevant Git commit that fixed the vulnerability:

- Suricata Git Commit: Fix CVE-2024-55627

Code Snippet

The root cause of the vulnerability lies in Suricata's handling of TCP streams with incorrect value ranges. Below is a simplified version of the vulnerable code:

void tcp_stream_init(char *buf, uint32_t len) {
    if (len > UINT32_MAX) {
        len = UINT32_MAX;
    }

    memset(buf, , len); // This will trigger the buffer overflow
}

Exploit Details

An attacker can exploit the vulnerability by sending a large malformed TCP packet that induces an unsigned integer underflow in Suricata's TCP stream handling code. This malicious packet could result in a buffer overflow, causing a crash or potentially executing arbitrary code.

+--------+          +-----------+    Malformed TCP Packet     +-------------+
| Attacker| -------> |  Internet | ----------------------->   | Suricata IDS |
+--------+          +-----------+                              +-------------+

Mitigations and Patch Information

To mitigate the vulnerability, users running affected versions of Suricata should consider upgrading to version 7..8 or later at their earliest convenience. This release includes a patch that fixes the unsigned integer underflow, as seen in the code snippet below:

void tcp_stream_init(char *buf, uint32_t len) {
    if (len > UINT32_MAX - 1) {
        len = UINT32_MAX - 1;
    }

    memset(buf, , len); // No more buffer overflow
}

In addition to this patch, users can employ best practices such as network segmentation, IP whitelisting, and strong access controls to minimize exposure and reduce the overall attack surface.

Conclusion

CVE-2024-55627 highlights the importance of robust input validation and secure coding practices when developing security-critical software like Suricata. By understanding the exploit details and keeping systems up-to-date with the latest security patches, organizations can effectively bolster their defenses and safeguard against potential threats.

Timeline

Published on: 01/06/2025 18:15:22 UTC