Artifex Software Ghostscript Security Bypass Vulnerability [CVE-2019-3839]
CVE Number – CVE-2019-3839
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 affected software allows access to some privileged operators after the fix for CVE-2019-6116. 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 the file system on the targeted system.
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 git commits at the following links: commits 4ec9ca74bed49f2a82acb4bf430eae0d8b3b75c9 and db24f253409d5d085c2760c814c3e1d3fa2dac59
Fixed Software
- Artifex Software has released software patches at the following links: Hide pdfdict and GS_PDF_ProcSet (internal stuff for the PDF interp). and Fix lib/pdf2dsc.ps to use documented Ghostscript pdf procedures.
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.