CVE-2017-5849 in netpbm
Summary
by MITRE
tiffttopnm in netpbm 10.47.63 does not properly use the libtiff TIFFRGBAImageGet function, which allows remote attackers to cause a denial of service (out-of-bounds read and write) via a crafted tiff image file, related to transposing width and height values.
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Analysis
by VulDB Data Team • 09/08/2020
The vulnerability identified as CVE-2017-5849 affects the tiffttopnm utility within the netpbm package version 10.47.63, representing a critical security flaw that enables remote attackers to execute denial of service attacks through carefully crafted TIFF image files. This vulnerability resides in the improper utilization of the libtiff TIFFRGBAImageGet function, which serves as a core component for handling TIFF image data processing. The flaw specifically manifests when the utility processes images where width and height values become transposed during the image conversion process, creating a fundamental misalignment in memory allocation and data handling operations.
The technical implementation of this vulnerability stems from a fundamental error in how the tiffttopnm utility manages image dimensions when calling the TIFFRGBAImageGet function from the libtiff library. When a maliciously crafted TIFF file is processed, the utility incorrectly interprets the image dimensions, leading to out-of-bounds memory reads and writes. This occurs because the transposed width and height values cause the memory allocation logic to reference invalid memory locations, resulting in buffer overflows that can crash the application or potentially allow for more sophisticated exploitation techniques. The flaw operates at the intersection of image processing logic and memory management, creating a pathway for attackers to manipulate the application's memory behavior through seemingly innocuous image file inputs.
From an operational perspective, this vulnerability presents significant risks to systems that process TIFF images, particularly those that are exposed to untrusted input sources such as web applications, file upload handlers, or automated image processing pipelines. The denial of service impact can be severe as it can cause the tiffttopnm utility to crash repeatedly, rendering image processing capabilities unavailable to legitimate users. In environments where automated image conversion is critical for business operations, this vulnerability could lead to complete service disruption. The remote attack vector means that adversaries need not have physical access to the system, as they can simply upload or provide a malicious TIFF file through network-based interfaces to trigger the vulnerability. This makes the attack surface particularly broad and the potential impact more significant for organizations relying on netpbm utilities for image processing tasks.
The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds write vulnerabilities, both of which are directly manifested in this flaw's behavior. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, which covers network denial of service attacks, and potentially to T1059.007 for command and scripting interpreter usage if the exploitation extends beyond simple denial of service. The root cause analysis reveals that this issue represents a classic buffer management error where the application fails to properly validate or normalize image dimension parameters before invoking library functions that expect specific memory layouts. Organizations should implement immediate mitigations including updating to patched versions of netpbm, implementing input validation for TIFF files, and potentially employing sandboxing techniques for image processing tasks to prevent exploitation of this vulnerability across their infrastructure.
The broader implications of this vulnerability extend beyond immediate denial of service scenarios, as similar patterns of dimension mismanagement in image processing libraries have historically led to more severe exploitation vectors including arbitrary code execution. Security practitioners should consider this vulnerability as part of a larger class of issues affecting image processing utilities and recommend comprehensive code review processes for similar functions that handle image metadata and dimension calculations. The vulnerability also underscores the importance of proper library function usage and parameter validation in security-critical applications, particularly those that rely on third-party libraries for core functionality. Organizations should prioritize updating their netpbm installations to versions that address this specific flaw and implement monitoring for potential exploitation attempts targeting this vulnerability in their network traffic and system logs.