An issue was discovered in Artifex Ghostscript, under the CVE identifier CVE-2024-33871, that affects versions prior to 10.03.1. Ghostscript, a suite of software containing an interpreter for Adobe Systems' PostScript and Portable Document Format (PDF) page description languages, is widely used for PDF and PostScript processing tasks. The vulnerability lies within contrib/opvp/gdevopvp.c, which allows arbitrary code execution via a custom Driver library, making it exploitable through a crafted PostScript document.

This post will provide insights into the code snippet where the vulnerability resides, links to original references, and an overview of the exploit details. It is vital to understand these aspects to take necessary precautions and protect your systems from potential attacks based on this vulnerability.

Code Snippets

The vulnerability in Artifex Ghostscript can be traced back to the contrib/opvp/gdevopvp.c source file. Below, you can see the section of code responsible for loading custom Driver Libraries:

if (opvp_new_library(rname,&library)) {
    if (dd.device->param[OPVP_PARAM_LIBRARY].value.pointer == NULL
      || (dd.device->param[OPVP_PARAM_LIBRARY].value.pointer != NULL
       && device->param[OPVP_PARAM_LIBRARY].Current.Value.pointer != NULL
       && strcmp(device->param[OPVP_PARAM_LIBRARY].value.pointer, rname))) {

This code is designed to load an arbitrary dynamic library specified by the Driver parameter for the opvp and oprp devices. It is important to note that there are no restrictions on the naming of this dynamic library, which can potentially lead to the arbitrary code execution exploitation.

Original References

- NVD Entry for CVE-2024-33871
- Explore-DB Entry for CVE-2024-33871
- Artifex Security Advisory concerning CVE-2024-33871

Exploit Details

An attacker can craft a malicious PostScript document that specifies the arbitrary dynamic library to be loaded as the Driver parameter. When the Ghostscript engine tries to parse and process this document, it may load this malicious dynamic library, which, in turn, could allow arbitrary code execution.

This type of attack is typically conducted through a phishing email or social engineering, where the attacker seeks to trick the victim into opening a crafted PostScript document. Upon opening the document, the targeted system becomes potentially exploitable.

Conclusion

The discovery of this vulnerability in Artifex Ghostscript has largely impacted systems using versions before 10.03.1. As a result, it is crucial to stay informed and take appropriate actions to protect your systems from attacks based on this exploit. By understanding the code snippet, references, and exploit details, you can put in place mechanisms that effectively mitigate the risks associated with CVE-2024-33871.

Timeline

Published on: 07/03/2024 19:15:03 UTC
Last modified on: 07/08/2024 14:18:32 UTC