CVE-2015-8668 in LibTIFF
Summary
by MITRE
Heap-based buffer overflow in the PackBitsPreEncode function in tif_packbits.c in bmp2tiff in libtiff 4.0.6 and earlier allows remote attackers to execute arbitrary code or cause a denial of service via a large width field in a BMP image.
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Analysis
by VulDB Data Team • 07/02/2022
The vulnerability identified as CVE-2015-8668 represents a critical heap-based buffer overflow within the libtiff library's bmp2tiff utility, specifically affecting the PackBitsPreEncode function in the tif_packbits.c file. This flaw exists in libtiff versions 4.0.6 and earlier, making it a significant security concern for systems that process bitmap images through this library. The vulnerability manifests when processing BMP images with an oversized width field, creating conditions that allow attackers to manipulate heap memory structures through crafted input data.
The technical implementation of this vulnerability stems from inadequate input validation within the PackBitsPreEncode function which fails to properly bounds-check the width field of BMP images before attempting to allocate memory for compression operations. When a maliciously crafted BMP image contains an excessively large width value, the function calculates a buffer size based on this invalid input without proper sanitization. This leads to heap memory allocation that is insufficient for the actual data processing requirements, resulting in memory corruption when the system attempts to write beyond allocated buffer boundaries. The flaw operates at the intersection of memory management and input validation, creating a classic heap overflow condition that can be exploited to execute arbitrary code or cause system crashes.
From an operational perspective, this vulnerability presents substantial risk to systems that process untrusted image data, particularly those utilizing libtiff for image conversion and manipulation tasks. The attack vector is remote, meaning that adversaries can exploit this vulnerability through network-based image processing workflows without requiring local access to the target system. This makes it particularly dangerous in web applications, file processing services, and automated image handling systems where users can upload BMP files. The potential impact includes complete system compromise through arbitrary code execution, or more commonly, denial of service conditions that can disrupt legitimate operations and potentially enable further exploitation attempts. The vulnerability's exploitation requires minimal privileges and can be automated, making it attractive to attackers seeking to compromise systems at scale.
Organizations should prioritize immediate remediation by upgrading to libtiff version 4.0.7 or later, which contains the necessary patches to address this buffer overflow condition. Additionally, implementing input validation measures such as strict BMP file format checking and width field bounds enforcement can provide defense-in-depth protection. Security teams should also consider deploying network-based intrusion detection systems that can identify and block suspicious BMP file uploads, particularly in environments where user-supplied image data is processed. The vulnerability aligns with CWE-121, heap-based buffer overflow, and represents a potential pathway for techniques described in the MITRE ATT&CK framework under T1059 for command and control execution, as well as T1499 for network denial of service. Regular security assessments of image processing pipelines and comprehensive vulnerability scanning should be conducted to identify any other potentially affected components within the system architecture.