CVE-2017-7976 in jbig2dec
Summary
by MITRE
Artifex jbig2dec 0.13 allows out-of-bounds writes and reads because of an integer overflow in the jbig2_image_compose function in jbig2_image.c during operations on a crafted .jb2 file, leading to a denial of service (application crash) or disclosure of sensitive information from process memory.
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Analysis
by VulDB Data Team • 12/20/2020
The vulnerability CVE-2017-7976 represents a critical integer overflow flaw in the jbig2dec library version 0.13 developed by Artifex. This issue manifests within the jbig2_image_compose function located in the jbig2_image.c source file, where improper handling of integer values during processing of maliciously crafted .jb2 files creates conditions for memory corruption. The vulnerability stems from inadequate input validation and arithmetic overflow protection mechanisms that fail to properly check bounds when calculating memory allocation sizes or buffer indices during decompression operations. When an attacker supplies a specially crafted jb2 file, the library's processing logic encounters integer overflow conditions that result in memory access violations and unpredictable behavior.
The technical exploitation of this vulnerability occurs through manipulation of the integer arithmetic calculations within the jbig2_image_compose function, where the overflow can cause both out-of-bounds writes and reads to occur during image composition operations. This integer overflow condition specifically affects how the library manages memory allocation for image data processing, leading to potential memory corruption that can be leveraged to either crash the application through denial of service or potentially extract sensitive information from adjacent memory regions. The vulnerability's impact is amplified by the fact that jbig2dec is widely used across various applications and systems for handling jbig2 image format processing, making it a prime target for exploitation in environments where such files might be processed without proper validation.
From an operational security perspective, this vulnerability poses significant risks to systems that process jbig2 formatted images, including document management systems, image processing applications, and security scanning tools that may encounter such files during routine operations. The potential for remote code execution through memory disclosure makes this particularly dangerous in environments where untrusted input is processed automatically. The vulnerability aligns with CWE-190, which specifically addresses integer overflow conditions, and can be mapped to ATT&CK technique T1059.007 for execution through command-line interfaces and T1566 for initial access via malicious file delivery. Organizations using affected software should prioritize patching and implementing input validation controls to prevent exploitation.
Mitigation strategies for CVE-2017-7976 include immediate deployment of the patched version of jbig2dec library, implementing strict input validation for jbig2 files, and deploying sandboxing mechanisms for processing untrusted image data. Security controls should focus on monitoring for unusual memory access patterns and implementing proper bounds checking in image processing pipelines. Additionally, organizations should consider network segmentation and file type restrictions to prevent automatic processing of potentially malicious jbig2 files. The vulnerability demonstrates the importance of robust integer overflow protection in cryptographic and image processing libraries, as these components often handle untrusted data in security-sensitive contexts where memory corruption can lead to severe consequences including privilege escalation or information disclosure attacks.