CVE-2016-3623 in LibTIFF
Summary
by MITRE
The rgb2ycbcr tool in LibTIFF 4.0.6 and earlier allows remote attackers to cause a denial of service (divide-by-zero) by setting the (1) v or (2) h parameter to 0.
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Analysis
by VulDB Data Team • 04/30/2019
The vulnerability identified as CVE-2016-3623 affects the rgb2ycbcr utility within LibTIFF version 4.0.6 and earlier releases, representing a critical denial of service weakness that can be exploited remotely. This flaw specifically targets the parameter handling mechanism within the tool's image conversion functionality, where the rgb2ycbcr utility processes color space transformations from RGB to YCbCr format. The vulnerability manifests when attackers manipulate either the vertical (v) or horizontal (h) scaling parameters to a value of zero, creating a mathematical division operation that cannot be completed due to the zero divisor condition.
The technical implementation of this vulnerability stems from inadequate input validation and error handling within the rgb2ycbcr tool's parameter processing logic. When the v or h parameters are set to zero, the tool attempts to perform a division operation in its color conversion algorithms without proper boundary checks or exception handling. This fundamental programming flaw creates a divide-by-zero exception that causes the application to terminate abruptly, resulting in a denial of service condition that prevents legitimate users from accessing the tool's functionality. The vulnerability exists at the core level of the image processing pipeline where scaling factors are applied during color space conversion operations, making it particularly dangerous as it can be triggered through any input that passes through the affected utility.
From an operational perspective, this vulnerability poses significant risks to systems that rely on LibTIFF for image processing tasks, particularly in environments where remote code execution or input manipulation is possible. Attackers can exploit this weakness to disrupt services by simply sending specially crafted parameters to the rgb2ycbcr tool, causing system downtime and potentially impacting critical workflows that depend on image processing capabilities. The impact extends beyond simple service disruption as it can affect automated processes, web applications, and server environments that utilize LibTIFF for handling image conversions, potentially leading to cascading failures in dependent systems. The vulnerability is particularly concerning in multi-tenant environments where one compromised service could affect the entire system's availability.
Security professionals should implement immediate mitigations including upgrading to LibTIFF version 4.0.7 or later, which contains the necessary patches to address the divide-by-zero condition. Additionally, input validation mechanisms should be strengthened at the application level to prevent zero values from being passed to the rgb2ycbcr utility, and proper error handling should be implemented to gracefully manage invalid parameter values. Organizations should also consider implementing network segmentation and access controls to limit exposure of vulnerable systems to untrusted networks. The vulnerability aligns with CWE-369, which specifically addresses the issue of divide-by-zero conditions in software applications, and represents a classic example of how improper input validation can lead to system instability and denial of service attacks. This weakness may also be categorized under ATT&CK technique T1499.004 for network denial of service attacks, as it can be used to disrupt availability of system services through controlled input manipulation.