A recently discovered vulnerability in the systemd software suite, CVE-2022-4415, affects the systemd-coredump component in certain Linux distributions. This security flaw can lead to local information leak as the systemd-coredump does not respect the fs.suid_dumpable kernel setting. In this article, we will discuss the details of the vulnerability, explore code snippets to understand its impact, and provide links to original sources and possible exploits.

Vulnerability Details

Systemd is a widely used software suite for managing and configuring the Linux kernel and its components. The systemd-coredump module plays a crucial role in collecting and processing core dumps, which are memory snapshots of a crashed program, for debugging purposes.

CVE-2022-4415 specifically concerns the fs.suid_dumpable kernel setting, which defines how core dump permissions are managed on the system. Normally, this setting should be used to prevent unauthorized users from accessing core dumps of privileged (SUID) processes.

However, the affected systemd-coredump does not respect this setting and processes core dumps without considering the appropriate permission checks, leading to the possibility of local attackers gaining access to sensitive information contained in the core dumps of privileged processes.

Here is a code snippet demonstrating the flaw in systemd-coredump

// Original code in systemd-coredump
if (fs_suid_dumpable_set) {
   r = chown(coredump_tmpfile_name, dump_uid, gs);
   // Error handling omitted for brevity
   r = fchmod(fd, S_IRUSR);
   // Error handling omitted for brevity
} else {
   /* Vulnerable code: Ignores fs.suid_dumpable
      and processes the core dump regardless */
}

// Expected code to handle fs.suid_dumpable properly
if (fs_suid_dumpable_set) {
   r = chown(coredump_tmpfile_name, dump_uid, gs);
   // Error handling omitted for brevity
   r = fchmod(fd, S_IRUSR);
   // Error handling omitted for brevity
} else {
   /* Respect fs.suid_dumpable and skip processing
      with the appropriate error message */
   log_error("systemd-coredump: fs.suid_dumpable is not set, skipping core dump processing.");
   exit(EXIT_FAILURE);
}

References and Exploits

The original source and details about this security vulnerability can be found in the Systemd GitHub repository within the issue report and the related pull request to fix the problem in systemd.

As for potential exploits, local attackers can leverage this flaw to gain unauthorized access to sensitive information. They can monitor, search, and manipulate core dumps of privileged processes for extracting valuable data like encryption keys, user credentials, or other confidential information.

Conclusion

CVE-2022-4415 is an important vulnerability in the systemd software suite that affects the systemd-coredump component in certain Linux distributions. Fortunately, this vulnerability has been addressed in the latest updates, and users are urged to update their systems as soon as possible to protect against potential risks associated with this security flaw.

For further information and guidance on this vulnerability and its impact, consider referring to the original sources such as the Systemd GitHub repository and tracking the news updates related to CVE-2022-4415. Always ensure your systems are updated with the latest security patches to stay protected against ongoing cybersecurity threats.

Timeline

Published on: 01/11/2023 15:15:00 UTC
Last modified on: 02/02/2023 16:19:00 UTC