CVE-2015-0295 in Digia
Summary
by MITRE
The BMP decoder in QtGui in QT before 5.5 does not properly calculate the masks used to extract the color components, which allows remote attackers to cause a denial of service (divide-by-zero and crash) via a crafted BMP file.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 05/01/2022
The vulnerability identified as CVE-2015-0295 resides within the Qt framework's QtGui module, specifically affecting versions prior to 5.5. This issue manifests in the Bitmap (BMP) image decoder implementation where improper mask calculation leads to critical system instability. The flaw represents a classic case of insufficient input validation and boundary checking that can be exploited by malicious actors to disrupt system operations through carefully crafted malicious BMP files.
The technical root cause of this vulnerability stems from the BMP decoder's failure to properly calculate color component masks during image processing. When processing malformed BMP files, the decoder attempts to perform division operations using calculated mask values that may evaluate to zero, resulting in a divide-by-zero exception. This mathematical error directly translates into application crashes and system instability, as the Qt framework's image handling mechanism lacks proper error recovery mechanisms for such edge cases. The vulnerability operates at the image parsing layer where the decoder extracts color information from the bitmap structure, making it particularly dangerous as it can be triggered during normal image loading operations.
From an operational perspective, this vulnerability presents a significant denial of service threat that can be exploited remotely through web applications, email clients, or any system that processes BMP images without proper sanitization. Attackers can craft malicious BMP files that, when loaded by vulnerable applications, will trigger the divide-by-zero condition and cause immediate application termination. The impact extends beyond simple service disruption as this vulnerability can be leveraged in broader attack chains where multiple applications relying on Qt frameworks are simultaneously compromised, potentially leading to cascading failures in enterprise environments where image processing is prevalent. The vulnerability aligns with CWE-369, which specifically addresses the issue of divide-by-zero conditions in software implementations.
The exploitation of this vulnerability can be accomplished through various attack vectors including web-based delivery, email attachments, or file sharing systems where BMP images are processed automatically. Security practitioners should note that this vulnerability affects not only web browsers but also desktop applications, mobile applications, and server-side components that utilize Qt's QtGui module for image processing. The ATT&CK framework categorizes this as a denial of service attack through software exploitation, specifically under the technique of "Exploitation for Privilege Escalation" when considering the potential for broader system compromise through application crashes. Organizations should implement immediate mitigations including updating to Qt 5.5 or later versions, implementing strict image validation policies, and deploying network-based intrusion detection systems to monitor for suspicious BMP file patterns.
Mitigation strategies for CVE-2015-0295 should prioritize immediate patching of affected Qt installations to version 5.5 or higher where the mask calculation logic has been corrected. Additionally, organizations should implement comprehensive input validation for all image file processing operations, including signature verification and size limitations for BMP files. Network security controls should be enhanced to filter potentially malicious image files at perimeter defenses, while application-level defenses should include robust error handling and resource isolation mechanisms to prevent cascading failures. Security monitoring should include detection of unusual application crash patterns and file processing anomalies that may indicate exploitation attempts. The vulnerability demonstrates the critical importance of proper input validation in graphics processing libraries and highlights the need for comprehensive security testing of multimedia handling components in software frameworks.