CVE-2007-0029 in Office
Summary
by MITRE
Microsoft Excel 2000 SP3, 2002 SP3, 2003 SP2, 2004 for Mac, and v.X for Mac allows user-assisted remote attackers to execute arbitrary code via a malformed string, aka "Excel Malformed String Vulnerability."
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Analysis
by VulDB Data Team • 07/13/2019
The CVE-2007-0029 vulnerability represents a critical buffer overflow flaw in Microsoft Excel versions spanning 2000 through 2004 for Mac platforms. This vulnerability stems from insufficient input validation within Excel's handling of malformed string data structures, creating a pathway for malicious code execution when specially crafted spreadsheet files are opened. The flaw specifically affects Excel 2000 Service Pack 3, Excel 2002 Service Pack 3, Excel 2003 Service Pack 2, and the Mac versions of Excel 2004 and v.X, indicating a widespread impact across Microsoft's spreadsheet software ecosystem during that era.
The technical mechanism behind this vulnerability involves the improper parsing of string data within Excel's file processing engine. When Excel encounters a malformed string structure in a spreadsheet file, the application fails to properly bounds-check the data before processing it, leading to memory corruption. This buffer overflow condition allows attackers to overwrite adjacent memory locations with malicious code, potentially enabling arbitrary code execution with the privileges of the user running Excel. The vulnerability operates under CWE-121, which classifies buffer overflow conditions where insufficient bounds checking allows memory to be overwritten, and aligns with ATT&CK technique T1059.005 for execution through macro languages, as the malicious payload often leverages Excel's macro capabilities to achieve code execution.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a means to compromise entire systems through user-assisted remote attacks. Since the vulnerability requires user interaction to open a malicious file, it typically manifests through social engineering campaigns where users are tricked into opening infected spreadsheet documents. This attack vector makes the vulnerability particularly dangerous in enterprise environments where users may inadvertently open malicious files from email attachments or shared network drives. The vulnerability's presence in multiple Excel versions indicates that organizations running any of these affected platforms were at risk, creating a broad attack surface that could be exploited across various organizational boundaries.
Mitigation strategies for CVE-2007-0029 primarily focus on immediate patching of affected Excel versions, as Microsoft released security updates specifically addressing this vulnerability. Organizations should implement strict file validation policies, including disabling macro execution in spreadsheets from untrusted sources and employing content filtering solutions that can detect and block malicious Excel files. Network-based security measures such as email filtering and web proxy configurations should be enhanced to prevent users from accessing potentially malicious spreadsheet files. Additionally, user education programs should emphasize the importance of verifying file sources and avoiding opening unexpected spreadsheet attachments. The vulnerability demonstrates the importance of maintaining up-to-date software patches and implementing defense-in-depth strategies, as it could be exploited to establish persistent access to compromised systems through the execution of malicious macros or scripts within Excel's environment.