Adobe Acrobat Reader DC, a widely used application for viewing, printing, and annotating PDF documents, has been identified with a serious vulnerability. This vulnerability, tagged as CVE-2022-24101, impacts multiple versions of Acrobat Reader DC, specifically the versions mentioned below:

17.012.30205 and earlier

This vulnerability is categorized as a use-after-free bug that could potentially expose sensitive memory content. If exploited, an attacker can leverage this information to bypass security measures such as Address Space Layout Randomization (ASLR). However, exploiting this issue requires user interaction, i.e., the user must open a malicious file.

In this post, we will delve into the details of CVE-2022-24101, examine a code snippet that demonstrates the vulnerability, provide links to relevant references, and discuss potential exploit methods.

Code Snippet

While the exact code responsible for this vulnerability in Acrobat Reader DC is not public, a generic use-after-free code snippet may look like the following:

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

int main() {
  int *ptr = (int *)malloc(sizeof(int));
  *ptr = 100;

  free(ptr); // Memory is freed here

  *ptr = 200; // Use-after-free vulnerability
  printf("Value after free: %d\n", *ptr);

  return ;
}

In this example, the memory block is allocated using malloc(), filled with a value, and then freed using free(). However, after freeing the memory block, the pointer is accessed and modified again, leading to a use-after-free vulnerability.

Original References

Adobe has published a security advisory on this vulnerability, which can be found at the following link:
Adobe Security Advisory APSB22-05

The CVE details can also be found in the following CVE database

CVE-2022-24101 NVD Entry

Exploit Details

As previously mentioned, exploiting this vulnerability requires user interaction. An attacker would need to create a malicious PDF file designed to trigger the use-after-free bug, and then deliver the file to the victim. Upon opening the malicious file with a vulnerable version of Acrobat Reader DC, the sensitive memory content could be exposed, potentially allowing the attacker to bypass ASLR.

Mitigations

To mitigate this vulnerability, Adobe has released updates for the affected Acrobat Reader DC versions:

Update to 17.012.30206 for 17.012.30205 and earlier

Users are advised to apply these updates as soon as possible. Additionally, practicing good security hygiene by avoiding opening PDF files from untrusted sources can also help prevent the exploitation of this vulnerability.

Conclusion

The CVE-2022-24101 vulnerability in Acrobat Reader DC is a serious use-after-free bug that, if exploited, can lead to sensitive memory disclosure and bypass of security mitigations such as ASLR. To protect themselves, users should update their Acrobat Reader DC software to the latest version and exercise caution when opening PDF files, especially those obtained from unknown or untrusted sources.

Timeline

Published on: 05/11/2022 18:15:00 UTC
Last modified on: 05/18/2022 16:21:00 UTC