CVE-2011-0104 in Excel
Summary
by MITRE
Microsoft Excel 2002 SP3 and 2003 SP3, Office 2004 and 2008 for Mac, and Open XML File Format Converter for Mac allow remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted HLink record in an Excel file, aka "Excel Buffer Overwrite Vulnerability."
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Analysis
by VulDB Data Team • 06/03/2025
The CVE-2011-0104 vulnerability represents a critical buffer overflow flaw in Microsoft Excel and related office applications that has significant implications for enterprise security environments. This vulnerability specifically affects Microsoft Excel 2002 SP3 and 2003 SP3 versions, as well as Office 2004 and 2008 for Mac, and the Open XML File Format Converter for Mac. The flaw manifests through a maliciously crafted HLink record within Excel files, which when processed by the affected applications, can trigger memory corruption leading to arbitrary code execution or denial of service conditions. This vulnerability demonstrates the inherent risks associated with complex spreadsheet processing engines that must handle various file formats and embedded data structures.
The technical mechanism behind this vulnerability involves improper bounds checking within the Excel application's handling of HLink records, which are used to store hyperlink information within spreadsheet files. When an attacker crafts a specially formatted Excel file containing an oversized or malformed HLink record, the application's memory management routines fail to properly validate the record size before attempting to process it. This allows the attacker to overwrite adjacent memory locations with controlled data, potentially leading to code execution at the privilege level of the affected user. The vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions where insufficient bounds checking permits adjacent memory to be overwritten, and also relates to CWE-125, which covers out-of-bounds read conditions that can lead to memory corruption.
The operational impact of CVE-2011-0104 extends far beyond simple denial of service scenarios, as it provides attackers with a pathway for remote code execution within targeted environments. Organizations running affected versions of Microsoft Office face significant risk from spear-phishing campaigns where malicious Excel files are delivered as email attachments, or from compromised websites that serve malicious content. The vulnerability is particularly dangerous in enterprise settings where users may have elevated privileges or where the applications are used to process sensitive business data. Attackers can leverage this vulnerability to establish persistent access, escalate privileges, or deploy additional malware payloads, making it a preferred target for advanced persistent threats. The attack surface is broad due to the widespread use of Excel across organizations and the typical user behavior of opening email attachments without proper security validation.
Mitigation strategies for CVE-2011-0104 should encompass multiple defensive layers following the principle of defense in depth. Organizations must prioritize immediate patching of all affected Microsoft Office versions through official Microsoft security updates, as these patches address the underlying buffer overflow conditions in the HLink record processing code. Network-based mitigations should include email filtering solutions that scan for suspicious Excel file attachments and implement strict content validation for Office documents. Additionally, users should be trained to avoid opening unexpected Excel files and to verify the source of documents before processing them. System hardening measures such as disabling automatic execution of macros, implementing application whitelisting policies, and using sandboxing technologies can significantly reduce the attack surface. From an ATT&CK framework perspective, this vulnerability maps to techniques involving execution through command and scripting interpreter and privilege escalation, making comprehensive endpoint protection and user awareness training essential components of the overall security posture.