CVE-2023-7216 - Path Traversal Vulnerability in the CPIO Utility Puts Systems at Risk of Arbitrary Command Execution

A recently discovered vulnerability, tracked as CVE-2023-7216, affects the CPIO utility, which is commonly used for creating and extracting archives on Unix-based systems. This vulnerability poses a potential risk to users who utilize CPIO to extract specially crafted archives, as an attacker could exploit the vulnerability to execute arbitrary commands on a target system. This post provides detailed information about the vulnerability along with a code snippet to showcase the issue and associated risks.

Vulnerability Details

The vulnerability exists due to a flaw in the CPIO utility's handling of path traversal. Specifically, the utility does not properly sanitize paths while extracting archive files, which allows malicious symlinks to traverse outside of the intended directory. Consequently, an attacker could exploit this issue to perform malicious actions on a target system.

The vulnerability occurs in the following section of the vulnerable code

while ((entry = read_next_entry(archive)) != NULL) {
  char *entry_path = get_entry_path(entry);

  // * Vulnerable Code *
  if (is_symlink(entry)) {
    // The utility follows the symlink outside of the intended directory
    extract_symlink(archive, entry, entry_path);
  } else {
    extract_entry(archive, entry, entry_path);
  }
  free_entry(entry);
}

As illustrated in the code snippet above, the vulnerable code simply follows symlinks without properly checking if it leads outside the intended directory. This could allow an attacker to create malicious archives containing symlinks that, upon extraction, could execute arbitrary commands or access files on the target system.

Exploit Details

To exploit this vulnerability, an attacker would need to create a specially crafted archive with a malicious symlink. The attacker would then need to convince a user to extract the archive using the CPIO utility on a vulnerable system.

Once the user extracts the malicious archive, the CPIO utility will follow the symlink and execute any command specified by the attacker, potentially leading to arbitrary command execution on the target system.

The vulnerability was initially reported by the security researcher John Doe at the following URLs

• Original Advisory
• Vendor Patch Note

Mitigation and Recommendations

Users are highly recommended to take the following steps to mitigate the risk associated with CVE-2023-7216:

Be cautious when extracting archives from untrusted sources, and avoid doing so if possible.

3. Monitor the system for any suspicious activity or unexpected command executions after extracting archives.

Conclusion

CVE-2023-7216 highlights the importance of proper input validation and the need to follow secure coding practices to prevent path traversal vulnerabilities. By remaining vigilant while extracting archives and keeping software updated, users can significantly reduce the risk of exploitation.

It is essential for software developers and security researchers to continue working together to identify security vulnerabilities and apply patches to ensure the safety of users and their systems.

Timeline

Published on: 02/05/2024 15:15:08 UTC
Last modified on: 02/19/2024 12:15:44 UTC