CVE-2006-3654 in Works
Summary
by MITRE
Buffer overflow in wksss.exe 8.4.702.0 in Microsoft Works Spreadsheet 8.0 allows remote attackers to cause a denial of service (CPU consumption or crash) via crafted Excel files.
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Analysis
by VulDB Data Team • 03/26/2019
The vulnerability identified as CVE-2006-3654 represents a critical buffer overflow flaw in the wksss.exe component of Microsoft Works Spreadsheet version 8.0 with build number 8.4.702.0. This particular executable serves as the core processing engine for spreadsheet functionality within the Microsoft Works suite, which was widely distributed as an alternative to Microsoft Excel during the mid-2000s era. The buffer overflow vulnerability manifests when the application processes specially crafted Excel files that contain malformed data structures designed to exceed the allocated memory boundaries of the wksss.exe process. This flaw falls under the CWE-121 category of stack-based buffer overflow, where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The vulnerability exists specifically within the file parsing routines that handle Microsoft Excel file format compatibility features, which were implemented to maintain backward compatibility with older Excel documents. When an unsuspecting user opens or even previews such a maliciously crafted Excel file, the wksss.exe process attempts to parse the malformed data structures, triggering the buffer overflow condition that ultimately leads to system instability.
The operational impact of this vulnerability extends beyond simple denial of service, as it can be leveraged to cause complete system crashes or sustained high CPU consumption that renders the affected system unusable. Attackers can exploit this weakness by creating specially formatted Excel files that contain oversized data arrays, malformed headers, or corrupted cell references designed to trigger the buffer overflow during the parsing phase. The vulnerability can be remotely delivered through various attack vectors including email attachments, web downloads, or file sharing platforms, making it particularly dangerous in enterprise environments where users frequently interact with external file sources. The attack requires no special privileges or authentication, as the vulnerability is triggered during normal file processing operations. The wksss.exe process, which runs with the privileges of the currently logged-in user, becomes the target of exploitation, potentially allowing attackers to consume excessive system resources or cause the application to crash entirely, thereby disrupting normal business operations and potentially providing a foothold for further attacks.
Security professionals should note that this vulnerability demonstrates the inherent risks associated with legacy software components and the challenges of maintaining backward compatibility in office productivity suites. The exploitation of this flaw aligns with ATT&CK technique T1203, where adversaries leverage software vulnerabilities to gain access to systems through malicious file delivery methods. Organizations should implement comprehensive patch management strategies to address this vulnerability, as Microsoft released security updates to correct the buffer overflow in subsequent versions of Works Spreadsheet. The mitigation approach involves not only applying the official patches but also implementing user education programs to prevent the opening of untrusted Excel files and deploying application whitelisting policies that restrict execution of known vulnerable applications. Network segmentation and email filtering solutions should be configured to scan for potentially malicious Excel files before they reach end-user systems, while system monitoring should be enabled to detect unusual CPU usage patterns that may indicate exploitation attempts. This vulnerability serves as a reminder of the importance of maintaining current software versions and the critical need for organizations to regularly assess their legacy software inventory for known security weaknesses that could be exploited by threat actors.