CVE-2011-3403 in Excel
Summary
by MITRE
Microsoft Excel 2003 SP3 and Office 2004 for Mac do not properly handle objects in memory, which allows remote attackers to execute arbitrary code via a crafted Excel spreadsheet, aka "Record Memory Corruption Vulnerability."
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 03/20/2021
The vulnerability identified as CVE-2011-3403 represents a critical memory corruption flaw affecting Microsoft Excel 2003 SP3 and Office 2004 for Mac applications. This issue stems from improper handling of objects within memory structures during spreadsheet processing, creating a pathway for remote code execution attacks. The vulnerability specifically targets the record memory management mechanisms within Excel's parsing engine, where malformed data structures can cause unpredictable behavior in memory allocation and deallocation processes.
The technical nature of this flaw aligns with CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds writes in memory operations. Attackers can exploit this vulnerability by crafting specially designed Excel spreadsheets containing malformed records that trigger memory corruption when processed by the vulnerable applications. The flaw occurs during the parsing of structured data within Excel files, where insufficient validation of record boundaries and memory pointers leads to buffer overflows or memory corruption that can be leveraged to execute arbitrary code with the privileges of the targeted user.
Operationally, this vulnerability presents significant risks to organizations relying on legacy Excel installations, as it enables remote code execution without requiring user interaction beyond opening a malicious file. The attack surface extends to any environment where users might encounter untrusted Excel documents, including email attachments, web downloads, and file sharing platforms. The exploitation typically requires the victim to open the malicious spreadsheet, making it particularly dangerous in social engineering campaigns where users might be tricked into opening seemingly legitimate documents. The vulnerability's impact is amplified by the widespread use of these older Excel versions in enterprise environments where software updates may be delayed or restricted.
Mitigation strategies for CVE-2011-3403 should prioritize immediate patching of affected systems with Microsoft security updates, as the vendor released specific fixes for this vulnerability in their regular security bulletins. Organizations should implement strict file validation policies, including the use of file type restrictions and content scanning mechanisms to prevent execution of potentially malicious Excel files. Network-based protections such as email filtering and web proxy configurations can help block malicious attachments before they reach end users. Additionally, security awareness training should emphasize the dangers of opening unexpected Excel files, particularly those received via email or downloaded from untrusted sources. The implementation of application whitelisting policies can further reduce risk by restricting execution of unauthorized Excel versions and preventing exploitation of the memory corruption vulnerability through controlled application environments.