Artifex Software Ghostscript DefineResource dSAFER Security Bypass Vulnerability [CVE-2019-3838]
CVE Number – CVE-2019-3838
A vulnerability in Artifex Software Ghostscript could allow an unauthenticated, remote attacker to bypass security restrictions on a targeted system.The vulnerability exists because the forceput operator could be extracted from the DefineResource method of the affected software. An attacker could exploit this vulnerability by persuading a user to open a crafted PostScript file that submits malicious input to the targeted system. A successful exploit could allow the attacker to bypass the -dSAFER protection in the affected application, which could allow the attacker to access sensitive information or execute arbitrary code on the targeted system.Proof-of-concept (PoC) code that demonstrates an exploit of this vulnerability is publicly available.Artifex Software has confirmed the vulnerability and released software updates.
Analysis
- To exploit this vulnerability, the attacker may use misleading language or instructions to persuade a user to access a PostScript file that submits malicious input to the targeted system.
Safeguards
- Administrators are advised to apply the appropriate updates.Administrators are advised to allow only trusted users to have network access.Administrators are advised to use an unprivileged account when browsing the Internet.Administrators are advised to monitor critical systems.Users are advised not to open email messages from suspicious or unrecognized sources. If users cannot verify that links or attachments included in email messages are safe, they are advised not to open them.Users are advised not to visit websites or follow links that have suspicious characteristics or cannot be verified as safe.
Vendor Announcements
- Artifex Software has released a bug reports at the following links: Bug 700576 and Bug 700576(Redux)
Fixed Software
- Artifex Software has released a software patches at the following links: [PATCH] Bug 700576: Make a transient proc executeonly (in DefineResource) and [PATCH] Bug 700576(redux): an extra transient proc needs executeonly’ed
Duncan is a technology professional with over 20 years experience of working in various IT roles. He has a interest in cyber security, and has a wide range of other skills in radio, electronics and telecommunications.