CVE-2015-8784 in LibTIFF
Summary
by MITRE
The NeXTDecode function in tif_next.c in LibTIFF allows remote attackers to cause a denial of service (out-of-bounds write) via a crafted TIFF image, as demonstrated by libtiff5.tif.
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Analysis
by VulDB Data Team • 07/24/2022
The vulnerability identified as CVE-2015-8784 resides within the NeXTDecode function located in the tif_next.c file of the LibTIFF library, representing a critical security flaw that enables remote attackers to execute denial of service attacks through carefully crafted TIFF image files. This issue specifically manifests as an out-of-bounds write condition that occurs when processing malformed NeXT image format data, making it particularly dangerous in environments where TIFF files are processed without proper validation. The vulnerability was demonstrated using a specific test file named libtiff5.tif, which showcases how the improper bounds checking in the decoding routine can be exploited to overwrite memory locations beyond the allocated buffer boundaries.
The technical implementation of this vulnerability stems from inadequate input validation within the NeXTDecode function, which fails to properly verify the dimensions and structure of incoming NeXT format image data before attempting to decode and write to memory buffers. When a maliciously constructed TIFF image is processed, the function does not adequately validate the expected data size or boundaries, leading to memory corruption that results in an out-of-bounds write operation. This flaw falls under the Common Weakness Enumeration category CWE-787, which specifically addresses out-of-bounds write vulnerabilities that occur when a program writes to memory locations beyond the boundaries of a buffer. The vulnerability is particularly concerning because it can be triggered remotely through network-based file processing, making it applicable to web applications, file processing services, and any system that handles untrusted TIFF image data without proper sanitization.
The operational impact of CVE-2015-8784 extends beyond simple denial of service conditions, as the out-of-bounds write can potentially lead to more severe consequences including application crashes, system instability, and in some scenarios, arbitrary code execution depending on the specific memory layout and exploitation context. Systems utilizing LibTIFF for image processing, including web servers handling image uploads, content management systems, digital asset management platforms, and image processing pipelines, are all at risk when running vulnerable versions of the library. The vulnerability affects a wide range of applications that depend on LibTIFF for TIFF file handling, particularly those in the graphic design, publishing, and digital imaging industries where TIFF format is commonly used for high-quality image storage and transmission. Attackers can exploit this vulnerability by simply uploading or transmitting a crafted TIFF file, making it an attractive target for automated exploitation campaigns.
Mitigation strategies for this vulnerability primarily involve immediate patching of affected LibTIFF installations to the latest versions that contain the necessary fixes for the NeXTDecode function. System administrators should prioritize updating their LibTIFF libraries and ensure that all applications relying on this library are also updated to prevent exploitation. Additionally, implementing input validation and sanitization measures at the application level can provide defense-in-depth protection, including validating file formats, checking file headers, and implementing proper error handling for malformed image data. Network-level protections such as file type filtering, content inspection, and sandboxing of image processing operations can further reduce the attack surface. Organizations should also consider implementing monitoring and alerting for unusual application behavior that might indicate exploitation attempts, particularly in environments where TIFF files are frequently processed. The ATT&CK framework categorizes this vulnerability under the T1203 technique for "Exploitation for Client Execution" and T1499.004 for "Endpoint Denial of Service" when considering the broader attack patterns that leverage such memory corruption vulnerabilities to disrupt system operations.