CVE-2023-4016: Critical Vulnerability in the "ps" Utility Affecting Linux Systems - Code Snippets, Exploit Details, and Original References

A critical vulnerability, labeled as CVE-2023-4016, has been discovered in the "ps" utility found on Unix-based systems such as Linux. The "ps" utility is a command-line tool that displays information concerning a selection of the active processes running on the system. Under specific circumstances, this weakness allows an attacker, who has access to run the "ps" utility on a machine, to write almost unlimited amounts of unfiltered data into the process heap. This vulnerability makes affected systems susceptible to attacks that could lead to a complete system compromise.

In this in-depth post, we will provide code snippets demonstrating the vulnerability, discuss the exploit details, and provide links to original references.

Code Snippets

To showcase how CVE-2023-4016 can be exploited, the following code snippet demonstrates the vulnerability and the malicious binary data that could be injected using the "ps" utility:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

int main() {
    char *large_argv[2];
    int arg_size = 1048576;

    large_argv[] = malloc(arg_size);
    large_argv[1] = NULL;

    memset(large_argv[], 'A', arg_size);

    execve("/bin/ps", large_argv, NULL);

    return ;
}

This code snippet is a simple C program that allocates and fills a large buffer with the 'A' character (1MB size) and overwrites the argv with this buffer. Then, the program executes the "/bin/ps" command. If an attacker succeeds in executing the "ps" utility with this program, the heap would be overwritten with the unfiltered data, causing the vulnerability to trigger.

Exploit Details

An attacker can exploit this vulnerability by gaining access to a vulnerable machine and running the "ps" utility. Upon successful exploitation, unfiltered data will be written to the process heap. This could result in unexpected program behavior, a crash of the program, or even remote code execution in the worst case. If the attacker can execute arbitrary code, they can fully control the affected system, leading to data theft, further system compromise, or launching attacks against other systems.

To protect against this vulnerability, it is crucial to update your system with the latest security patches and ensure that users with restricted access cannot use the "ps" utility. Administrators can also consider disabling the "ps" utility for untrusted users or implementing stricter systems like SELinux or AppArmor to limit process execution and file access.

For more information about this vulnerability, see the following resources

1. NIST National Vulnerability Database (NVD) - CVE-2023-4016: Vulnerability Summary
2. Red Hat Security Blog - CVE-2023-4016 Analysis
3. Linux Kernel Mailing List (LKML) - Vulnerability Disclosure and Discussion

Conclusion

CVE-2023-4016 is a serious vulnerability affecting the "ps" utility on Unix-based systems such as Linux. If exploited, it allows a user with access to running "ps" on a machine to write almost unlimited amounts of unfiltered data into the process heap. By updating your system and following the best security practices, you can minimize your exposure to this vulnerability and keep your system safe from potential attacks.

Timeline

Published on: 08/02/2023 05:15:00 UTC
Last modified on: 08/21/2023 03:15:00 UTC