CVE-2018-16140 in fig2dev
Summary
by MITRE
A buffer underwrite vulnerability in get_line() (read.c) in fig2dev 3.2.7a allows an attacker to write prior to the beginning of the buffer via a crafted .fig file.
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Analysis
by VulDB Data Team • 05/06/2023
The buffer underwrite vulnerability identified as CVE-2018-16140 resides within the fig2dev tool version 3.2.7a, specifically in the get_line() function located in read.c. This flaw represents a critical security issue that can be exploited through manipulation of .fig input files, which are commonly used for storing vector graphics data in the Frame Grabber (FIG) format. The vulnerability manifests when the application processes malformed input files that trigger improper memory handling during line reading operations.
The technical nature of this vulnerability aligns with CWE-121, which describes buffer underflows or underwrites occurring when a program writes data to a memory location before the beginning of a buffer. In this case, the get_line() function fails to properly validate buffer boundaries when processing crafted .fig files, allowing an attacker to write data to memory locations preceding the allocated buffer space. This underwrite condition can overwrite adjacent memory segments including stack variables, return addresses, or other critical program data structures.
The operational impact of this vulnerability extends beyond simple memory corruption, as it creates potential pathways for arbitrary code execution. When an attacker crafts a malicious .fig file that triggers the buffer underwrite condition, they can manipulate program flow by overwriting return addresses or function pointers in the stack. This capability enables attackers to execute arbitrary code with the privileges of the user running the fig2dev application, potentially leading to complete system compromise. The vulnerability affects any system that processes .fig files through fig2dev, including desktop environments, server applications, and automated processing systems.
Security practitioners should consider this vulnerability in the context of the ATT&CK framework, particularly under the T1059.007 technique for command and scripting interpreter and T1203 for exploitation for privilege escalation. The vulnerability's exploitation requires minimal user interaction, as it can be triggered through normal file processing operations. Mitigation strategies should include immediate patching of fig2dev to version 3.2.8 or later, which contains the necessary memory boundary checks. Additionally, input validation should be implemented at the application level, including strict validation of .fig file formats and content prior to processing. Network-based mitigations such as file type filtering and sandboxing of .fig file processing can provide additional defense in depth. Organizations should also implement principle of least privilege for applications that process .fig files, ensuring that such processing occurs with minimal system privileges to limit potential damage from successful exploitation attempts.