CVE-2007-3890 in Excel
Summary
by MITRE
Microsoft Excel in Office 2000 SP3, Office XP SP3, Office 2003 SP2, and Office 2004 for Mac allows remote attackers to execute arbitrary code via a Workspace with a certain index value that triggers memory corruption.
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Analysis
by VulDB Data Team • 03/15/2021
This vulnerability resides in Microsoft Excel applications across multiple versions including Office 2000 SP3, Office XP SP3, Office 2003 SP2, and Office 2004 for Mac. The flaw manifests when processing Workspace files containing specific index values that cause memory corruption issues. This represents a classic buffer overflow condition where maliciously crafted Workspace files can trigger unauthorized code execution on vulnerable systems. The vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions, and aligns with ATT&CK technique T1059.005 for command and scripting interpreter execution. The memory corruption occurs during the parsing of Workspace file structures, specifically when handling index values that exceed expected bounds. Attackers can exploit this by crafting malicious Workspace files that contain malformed index values, which when opened by vulnerable Excel versions can lead to arbitrary code execution. The impact extends beyond simple code execution as this vulnerability can be leveraged for privilege escalation and system compromise. The affected versions span several years of Microsoft Office releases, indicating a long-standing issue that persisted through multiple service packs and updates. This vulnerability is particularly dangerous because Workspace files can be delivered through various attack vectors including email attachments, malicious websites, or compromised documents. The exploitation requires no user interaction beyond opening the malicious file, making it a significant threat in social engineering campaigns. Organizations running these older Office versions face heightened risk as the vulnerability has been widely documented and exploited in the wild. The root cause stems from inadequate input validation and memory management within Excel's Workspace file parser. This flaw demonstrates the critical importance of proper bounds checking and memory safety practices in office productivity software. The vulnerability affects both Windows and Mac platforms, indicating a systemic issue within Microsoft's implementation rather than platform-specific weaknesses.
The technical exploitation of this vulnerability involves crafting Workspace files with specific index values that cause Excel to allocate insufficient memory for processing the file structure. When Excel encounters these malformed indices, the application's memory management routines fail to properly handle the overflow condition, leading to memory corruption that can be leveraged for code execution. This type of vulnerability is particularly challenging to mitigate because it requires careful input validation at multiple layers of the application stack. The memory corruption typically manifests as stack corruption or heap corruption depending on how the vulnerable code handles the malformed indices. Attackers can potentially use this vulnerability to inject malicious code that executes with the privileges of the user running Excel. The exploitation process involves creating Workspace files with carefully calculated index values that cause the application to jump to attacker-controlled memory locations. This vulnerability represents a classic example of how legacy software can contain persistent security flaws that remain exploitable even after multiple updates. The vulnerability has been classified as a remote code execution flaw, meaning attackers do not need physical access to target systems. The widespread adoption of affected Office versions makes this vulnerability particularly dangerous in enterprise environments where older software versions may still be in use.
Mitigation strategies for this vulnerability include immediate deployment of Microsoft security patches and updates for the affected Office versions. Organizations should implement strict file validation policies and disable automatic opening of Workspace files. The recommended approach involves updating to supported Office versions that contain security fixes for this vulnerability. System administrators should also consider implementing application whitelisting policies to prevent execution of unauthorized code. Network-based mitigations include filtering Workspace file types at network boundaries and implementing email security solutions that scan for potentially malicious Office files. The vulnerability highlights the importance of maintaining up-to-date software and security patches as a fundamental defense mechanism. Regular security assessments should include inventory checks for legacy Office installations that may be vulnerable to this and similar issues. Security awareness training for end users remains crucial as social engineering remains a primary delivery method for exploiting this vulnerability. The vulnerability underscores the necessity of comprehensive vulnerability management programs that address both known and emerging threats. Organizations should also consider implementing endpoint detection and response solutions to identify potential exploitation attempts. The long-term solution involves phasing out legacy Office versions and migrating to supported releases that include modern security features and regular security updates. This vulnerability serves as a reminder of the critical importance of timely patch management and the risks associated with running unsupported software versions. The remediation process should include thorough testing of patches in controlled environments before widespread deployment to ensure compatibility with existing business applications.