A critical format string injection vulnerability, tracked as CVE-2022-33938, has been discovered in the ghome_process_control_packet functionality of Abode Systems, Inc., iota All-In-One Security Kit versions 6.9Z and 6.9X. The vulnerability allows an attacker to send a specially-crafted XCMD, which can lead to memory corruption, information disclosure, and denial of service. This blog post will walk you through the exploit details, an example code snippet, and provide links to the original references for more information.

Exploit Details

The vulnerability exists in the ghome_process_control_packet() function, which handles XML control messages sent by the attacker. By crafting a malicious XML payload with a specially designed format string, an attacker can trigger a format string injection leading to memory corruption, disclosure of sensitive information, and denial of service to the target.

The format string injection occurs when the vulnerable function reads an XCMD from the attacker's XML payload and passes it to a format string function, such as sprintf() or snprintf(), without validating or sanitizing it. Consequently, an attacker can exploit format string specifiers to manipulate memory or exfiltrate sensitive data.

Here is an example code snippet demonstrating the vulnerability

int ghome_process_control_packet(char *packet, int len) {
  char xcmd_buffer[256] = {};
  char response_buffer[1024] = {};

  // ...

  /* Read XCMD from packet (no validation/sanitization) */
  char *xcmd = get_xcmd_from_xml_packet(packet);

  /* Format string injection vulnerability */
  snprintf(response_buffer, 1024, xcmd);

  // ...

  return ;
}

In the example above, the attacker's XCMD is extracted from the XML packet and used as the format string input for snprintf(), without any validation or sanitization. An attacker can use this to exploit the format string injection vulnerability.

To exploit this vulnerability, an attacker can send a malicious XML payload containing the specially crafted XCMD to the target. Below is an example of a malicious payload that triggers the vulnerability:

<control>
  <command>%08x%08x%08x%08x%s...</command>
</control>

The issue has been assigned CVE-2022-33938, and as of now, there is no security patch available. Users are advised to regularly update their systems with the latest security patches and monitor any relevant advisories from Abode Systems, Inc.

Original References

For detailed information and further understanding of this vulnerability, please refer to the following sources:

1. CVE-2022-33938 - NIST National Vulnerability Database (NVD)
2. Abode Systems, Inc. Security Advisory

Conclusion

CVE-2022-33938 demonstrates the importance of properly validating and sanitizing user input, especially in critical systems like IoT devices and security products. In this case, the format string injection vulnerability in Abode iota All-In-One Security Kit allows an attacker to cause memory corruption, information disclosure, and denial of service. It is essential for developers to be aware of such security risks, mitigate them, and keep their systems up-to-date with security patches as they become available.

Timeline

Published on: 10/25/2022 17:15:00 UTC
Last modified on: 10/26/2022 16:12:00 UTC