CVE-2011-1278 in Excel
Summary
by MITRE
Microsoft Excel 2002 SP3 and Office 2004 for Mac do not properly validate record information during parsing of Excel spreadsheets, which allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted spreadsheet, aka "Excel WriteAV Vulnerability."
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Analysis
by VulDB Data Team • 11/09/2021
The CVE-2011-1278 vulnerability represents a critical memory corruption flaw in Microsoft Excel 2002 SP3 and Office 2004 for Mac applications. This vulnerability stems from inadequate validation of record information during the parsing process of Excel spreadsheet files, creating a pathway for malicious actors to exploit the software's parsing logic. The flaw specifically affects the way these applications handle structured data within Excel files, particularly when processing records that contain malformed or specially crafted data sequences. Security researchers have classified this issue as a buffer overflow vulnerability, where the application fails to properly bounds-check data structures during spreadsheet parsing operations, leading to potential memory corruption scenarios.
The technical execution of this vulnerability occurs when a maliciously crafted Excel spreadsheet is opened by an affected application. During the parsing process, the application encounters record data that exceeds expected boundaries or contains unexpected formatting patterns. This improper validation allows attackers to manipulate the memory layout of the running Excel process, potentially leading to arbitrary code execution or system instability. The vulnerability is particularly concerning because it can be triggered through simple file opening operations, requiring no special privileges or user interaction beyond opening the malicious file. This characteristic aligns with ATT&CK technique T1203, where adversaries leverage application vulnerabilities to execute code remotely. The memory corruption aspects of this vulnerability are consistent with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios that can result in memory corruption.
The operational impact of CVE-2011-1278 extends beyond simple denial of service scenarios to encompass full system compromise potential. When successfully exploited, the vulnerability allows remote attackers to execute arbitrary code with the privileges of the affected user, potentially enabling complete system takeover. This risk is particularly elevated in enterprise environments where users may inadvertently open malicious spreadsheets through email attachments or file downloads. The vulnerability affects both Windows and Mac platforms, demonstrating the cross-platform nature of certain Microsoft Office flaws. Organizations running these older versions face significant risk since they are no longer receiving security updates, making them prime targets for exploitation. The vulnerability's remote exploitation capability means that attackers can deliver malicious payloads through various channels including email, web downloads, or file sharing platforms, making it particularly dangerous in modern threat landscapes.
Mitigation strategies for CVE-2011-1278 should focus on immediate remediation through software updates and administrative controls. Microsoft has released patches for affected versions, but organizations running legacy systems must implement additional protective measures including email filtering, file extension restrictions, and user education regarding suspicious file attachments. Network-based protections such as sandboxing Excel applications and implementing strict file validation policies can significantly reduce exploitation risk. Security teams should also consider implementing application whitelisting policies that restrict execution of untrusted Office files. The vulnerability's classification as a memory corruption issue makes it particularly susceptible to exploit mitigation techniques including address space layout randomization and data execution prevention. Organizations should also consider deploying intrusion detection systems that can identify suspicious spreadsheet file patterns and monitor for exploitation attempts. Given the age of the affected software versions, many organizations may need to plan for complete software migration away from unsupported platforms to ensure long-term security posture maintenance.