CVE-2024-56378 - Critical Out-of-Bounds Read Vulnerability in libpoppler.so of Poppler through 24.12.: Exploit Details, Code Snippets, and References

A critical security vulnerability, CVE-2024-56378, has been discovered in the widely-used Poppler document rendering library, specifically affecting libpoppler.so in Poppler through version 24.12.. The flaw enables an out-of-bounds read vulnerability in the JBIG2Bitmap::combine function, located in the JBIG2Stream.cc file. This vulnerability could potentially be exploited by an attacker to cause a crash, extract sensitive information, or execute arbitrary code on a victim's system.

This long-read post aims to provide an in-depth analysis of the CVE-2024-56378 vulnerability, including specific details on the affected function, code snippets to illustrate the issue, links to the original references and announcements, as well as potential exploit scenarios.

Vulnerability Details

The CVE-2024-56378 vulnerability is caused by an improper boundary check in the JBIG2Bitmap::combine function, which is responsible for managing bitmap data in the JBIG2 decoding process. JBIG2 is a widely-used image compression standard, often employed within PDF documents as a way to store and display compressed images.

The out-of-bounds read error occurs when processing a specially crafted, malicious PDF document that contains a malformed JBIG2 image. The following code snippet demonstrates the problematic section of the JBIG2Bitmap::combine function within JBIG2Stream.cc:

void JBIG2Bitmap::combine(JBIG2Bitmap *bitmap, int xSrc, int ySrc,
                          int xDest, int yDest, int width, int height,
                          JBIG2Bitmap *maskBitmap, int xMask, int yMask) {
  ...
  // boundary check for reading
  if (xSrc <  || xDest <  || ySrc <  || yDest <  || width <  || height <  ||
      xSrc + width > bitmap->w || yDest + height > h ||
      xDest + width > w || ySrc + height > bitmap->h) {
    return;
  }
  ...
}

While the code snippet above does perform a series of boundary checks, it fails to properly validate all the input parameters. A specially crafted PDF file could manipulate these parameters to trigger an out-of-bounds read, potentially leading to unexpected behavior, crashes, or even code execution.

For more details, refer to the original vulnerability report and patch announcement

- Official CVE Record: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-56378
- Poppler Patch Commit: https://github.com/freedesktop/poppler/commit/ab48dc03

CVE-2024-56378 could potentially be exploited by an attacker in the following ways

1. Crafting a malicious PDF file containing a malformed JBIG2 image, and convincing the victim to open it using a PDF viewer that relies on the vulnerable Poppler library.
2. Creating a website that embeds a malicious PDF file, which then gets automatically rendered in a visitor's browser if the browser uses a vulnerable version of the Poppler library for PDF rendering.

In both cases, the attacker could potentially cause the PDF viewer or browser to crash, extract sensitive information from the application's memory space, or, in the worst-case scenario, execute arbitrary code on the victim's system.

Mitigation and Recommendations

To address the CVE-2024-56378 vulnerability, it is strongly recommended to update the Poppler library to the latest version, which includes the necessary patches to resolve the issue. Furthermore, users should exercise caution when opening PDF documents from untrusted sources, and consider using a secure PDF viewer that employs sandboxing techniques to minimize the impact of potential vulnerabilities.

In conclusion, the CVE-2024-56378 out-of-bounds read vulnerability in the libpoppler.so of Poppler through version 24.12. poses a significant security risk, potentially enabling attackers to compromise the confidentiality, integrity, and availability of affected systems. By understanding the exploit details, code snippets, and references provided in this long-read post, security professionals and software developers can better protect themselves and their users from potential exploitation.

Timeline

Published on: 12/23/2024 00:15:05 UTC
Last modified on: 12/26/2024 20:15:23 UTC