CVE-2022-23122 - Netatalk Remote Code Execution Vulnerability

CVE-2022-23122 is a critical remote code execution vulnerability discovered in Netatalk, an open-source implementation of the Apple Filing Protocol (AFP) that allows UNIX-based systems to serve as file servers for macOS clients. Remote attackers can exploit this vulnerability without authentication to execute arbitrary code in the context of the root user, thereby gaining complete control of the targeted system.

This vulnerability, previously known as ZDI-CAN-15837, is indexed in the Common Vulnerabilities and Exposures (CVE) database as CVE-2022-23122. In this post, we will outline the details of this vulnerability, steps to exploit it, and reference the original sources for further information.

Code Snippet

The vulnerability lies within the setfilparams function in Netatalk. The following is a simplified version of the vulnerable code:

void setfilparams(char *src, size_t len) {
  char dest[256];

  // Copy user-supplied data to the stack-based buffer without proper length validation
  memcpy(dest, src, len);
}

This code snippet demonstrates that the function setfilparams fails to validate the length of user-supplied data before copying it to a fixed-length stack-based buffer (i.e., dest). This oversight allows an attacker to exploit the vulnerability and execute arbitrary code as the root user in the targeted system.

To successfully exploit this vulnerability, an attacker must complete the following steps

1. Craft a malicious AFP packet with an oversized request that exceeds the size of the fixed-length stack-based buffer (dest). The proper structure and formatting of the AFP packet can be found in the Netatalk documentation (linked in the "References" section below).

Send the crafted malicious AFP packet to the target system running Netatalk.

3. Due to the lack of length validation of user-supplied data in the setfilparams function, the oversized request will lead to a buffer overflow.

4. Exploit the buffer overflow to obtain control of the program's execution flow and inject arbitrary code to be executed as the root user on the target system.

To increase the chances of successful exploitation, the attacker may need to perform additional steps such as bypassing security mechanisms, defeating address space layout randomization (ASLR), and chaining the vulnerability with other exploits.

References

- CVE-2022-23122 - NVD
- Netatalk Official Website
- AFP Specification - Apple Developer Documentation
- ZDI-CAN-15837 - Zero Day Initiative

Conclusion

CVE-2022-23122 is a serious remote code execution vulnerability affecting the widely-used Netatalk open-source project. By exploiting this vulnerability, an attacker can execute arbitrary code as the root user on the target system, leading to complete system compromise. As a result, it is crucial for organizations using Netatalk to apply the necessary security updates and follow the best security practices to mitigate the risks associated with this vulnerability.

Timeline

Published on: 03/28/2023 19:15:00 UTC
Last modified on: 04/03/2023 18:16:00 UTC