CVE-2010-3946 in Office
Summary
by MITRE
Integer overflow in the PICT image converter in the graphics filters in Microsoft Office XP SP3, Office 2003 SP3, and Office Converter Pack allows remote attackers to execute arbitrary code via a crafted PICT image in an Office document, aka "PICT Image Converter Integer Overflow Vulnerability."
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Analysis
by VulDB Data Team • 10/07/2021
The CVE-2010-3946 vulnerability represents a critical integer overflow flaw within Microsoft Office's PICT image conversion functionality, specifically affecting Office XP SP3, Office 2003 SP3, and the Office Converter Pack. This vulnerability resides in the graphics filters component that processes PICT (Picture) image format files, which are commonly embedded within Microsoft Office documents. The flaw manifests when the application attempts to convert PICT images to other formats, creating a scenario where an attacker can manipulate the image data to trigger an integer overflow condition. Such vulnerabilities are particularly dangerous because they can lead to arbitrary code execution, making them prime targets for exploitation in targeted attacks. The vulnerability operates by manipulating the size parameters within PICT image headers, causing the application to allocate insufficient memory buffers that can then be overwritten through carefully crafted input data.
The technical implementation of this vulnerability follows the common pattern of integer overflow exploits where a 32-bit signed integer becomes corrupted when processing large values, typically through addition or multiplication operations that exceed the maximum representable value. In this case, the PICT image converter performs calculations to determine buffer sizes needed for image data processing, and when these calculations exceed the maximum integer value, the result wraps around to a negative or extremely small value. This creates a situation where the application allocates a buffer that is significantly smaller than required for the actual image data, leading to memory corruption. The vulnerability is classified under CWE-190 as an integer overflow condition, specifically involving signed integer overflow that results in a wraparound condition. This type of flaw is particularly prevalent in legacy code where bounds checking may be insufficient or absent, and it aligns with ATT&CK technique T1203 which describes the exploitation of memory corruption vulnerabilities for code execution.
The operational impact of CVE-2010-3946 extends beyond simple denial of service scenarios, as successful exploitation can result in complete system compromise. Attackers can craft malicious PICT images that, when opened by an affected Office application, trigger the integer overflow condition and subsequently execute malicious code with the privileges of the user running the application. This makes the vulnerability particularly attractive for phishing campaigns and targeted attacks against enterprise environments where Office documents are frequently shared and opened. The exploitation typically requires social engineering to get users to open the malicious document, but once executed, the vulnerability can provide attackers with persistent access to the compromised system. Organizations running affected versions of Microsoft Office are particularly vulnerable since these applications were widely deployed in corporate environments, making the attack surface substantial. The vulnerability's persistence in older Office versions demonstrates how legacy software components can harbor security flaws that remain exploitable for years after initial discovery.
Mitigation strategies for CVE-2010-3946 require a multi-layered approach combining immediate patching with defensive measures. Microsoft released security updates that addressed the integer overflow condition in the PICT image converter, and organizations should prioritize applying these patches to all affected systems. However, given that many organizations may not be able to patch immediately, defensive measures such as disabling PICT image handling in Office applications or implementing strict file type restrictions can provide temporary protection. Network-based protections including email filtering and web application firewalls can help prevent the delivery of malicious PICT images through common attack vectors. Additionally, user education regarding suspicious document attachments and the importance of keeping software updated remains crucial in defending against this class of vulnerability. The vulnerability highlights the importance of proper input validation and bounds checking in graphics processing libraries, and it serves as a reminder of the need for regular security assessments of legacy software components that continue to be deployed in enterprise environments. Organizations should also consider implementing application whitelisting policies to prevent execution of untrusted image processing components and maintain comprehensive monitoring for suspicious file handling activities that might indicate exploitation attempts.