CVE-2016-7979 in Ghostscript
Summary
by MITRE
Ghostscript before 9.21 might allow remote attackers to bypass the SAFER mode protection mechanism and consequently execute arbitrary code by leveraging type confusion in .initialize_dsc_parser.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 12/07/2022
The vulnerability identified as CVE-2016-7979 affects Ghostscript versions prior to 9.21 and represents a critical security flaw that undermines the SAFER mode protection mechanism. This vulnerability specifically resides within the .initialize_dsc_parser function, which is responsible for parsing Digital Scripting Language files that are commonly used in PostScript and PDF document processing. The flaw enables remote attackers to bypass critical security controls that are designed to prevent arbitrary code execution, thereby creating a significant risk for systems that process untrusted document content.
The technical root cause of this vulnerability stems from a type confusion issue within the DSC parser implementation. Type confusion occurs when a program incorrectly handles data types during execution, leading to situations where memory operations may be performed on objects of unexpected types. In this case, the .initialize_dsc_parser function fails to properly validate or handle different data types during the parsing process, creating opportunities for attackers to manipulate the parser's behavior through carefully crafted input. This type confusion allows malicious actors to control memory layout and execution flow, effectively circumventing the SAFER mode protections that are intended to restrict dangerous operations within the Ghostscript interpreter.
The operational impact of CVE-2016-7979 is substantial, as it enables remote code execution in environments where Ghostscript is used to process untrusted documents. Systems that rely on Ghostscript for PDF rendering, PostScript processing, or document conversion are particularly vulnerable, including web applications, document management systems, and email servers that handle document attachments. The vulnerability can be exploited through various attack vectors such as malicious PDF files, PostScript documents, or web-based applications that utilize Ghostscript for document processing. This creates a wide attack surface that could potentially be leveraged by threat actors to gain unauthorized access to systems, establish persistent backdoors, or perform further lateral movement within networks.
The security implications extend beyond simple code execution, as this vulnerability directly violates fundamental security principles outlined in the CWE taxonomy under CWE-476, which addresses NULL pointer dereferences, and CWE-121, which covers stack-based buffer overflow conditions. The vulnerability also aligns with ATT&CK techniques categorized under T1059.007 for command and scripting interpreter and T1068 for exploit for privilege escalation, as successful exploitation could lead to privilege elevation and system compromise. Organizations using affected versions of Ghostscript should immediately implement mitigations including upgrading to version 9.21 or later, implementing network segmentation, and deploying intrusion detection systems to monitor for exploitation attempts. Additionally, input validation measures and sandboxing mechanisms should be strengthened to reduce the attack surface and limit potential damage from successful exploitation attempts.