CVE-2011-0977 in Excel
Summary
by MITRE
Use-after-free vulnerability in Microsoft Office XP SP3, Office 2003 SP3, Office 2007 SP2, Office 2004 and 2008 for Mac, and Open XML File Format Converter for Mac allows remote attackers to execute arbitrary code via malformed shape data in the Office drawing file format, aka "Microsoft Office Graphic Object Dereferencing Vulnerability."
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Analysis
by VulDB Data Team • 01/06/2025
The CVE-2011-0977 vulnerability represents a critical use-after-free flaw in multiple Microsoft Office versions including XP SP3, 2003 SP3, 2007 SP2, and their respective Mac counterparts. This vulnerability falls under the CWE-416 category, specifically addressing the improper handling of memory deallocation scenarios. The flaw manifests when Microsoft Office applications process malformed shape data within Office drawing file formats, creating a condition where memory previously allocated to graphic objects is accessed after it has been freed, leading to potential code execution. The vulnerability is particularly concerning as it affects both Windows and Mac platforms, demonstrating the widespread impact across Microsoft Office suites and highlighting the complexity of addressing memory safety issues in enterprise software environments.
The technical exploitation of this vulnerability occurs through the manipulation of Office drawing file formats, specifically targeting the graphic object handling mechanisms within the Office applications. When a maliciously crafted Office document containing malformed shape data is opened, the application's graphics processing engine attempts to free memory associated with graphic objects while simultaneously attempting to access that same memory location, creating a race condition that adversaries can leverage. This particular vulnerability aligns with ATT&CK technique T1203, which describes the exploitation of memory corruption vulnerabilities to achieve arbitrary code execution. The attack vector requires remote delivery through crafted Office documents, making it particularly dangerous in email-based attack scenarios where users might unknowingly open malicious attachments.
The operational impact of CVE-2011-0977 extends beyond simple code execution capabilities, as it provides attackers with the ability to bypass security controls and establish persistent access to compromised systems. Once successfully exploited, the vulnerability allows attackers to execute malicious code with the privileges of the user running the affected Office application, potentially leading to complete system compromise. The vulnerability's presence in multiple Office versions including legacy support products means that organizations with extended support cycles or those using older Office installations remain at risk, creating challenges for security teams who must balance patch deployment with operational stability. Organizations running affected versions are particularly vulnerable to targeted attacks and zero-day exploitation attempts, as the vulnerability's discovery often precedes official patch releases.
Mitigation strategies for this vulnerability require immediate patching of all affected Microsoft Office installations across both Windows and Mac platforms, as Microsoft released security updates specifically addressing this use-after-free condition. Network administrators should implement email filtering solutions to prevent the delivery of potentially malicious Office documents, while endpoint protection measures should be enhanced to detect and block suspicious file execution patterns. The vulnerability's classification as a memory corruption issue necessitates the implementation of exploit protection mechanisms such as address space layout randomization, data execution prevention, and heap spray protection measures. Organizations should also consider implementing application whitelisting policies to restrict execution of Office applications from untrusted sources and establish robust incident response procedures to quickly identify and contain exploitation attempts. Given the vulnerability's potential for privilege escalation and persistent access, regular security assessments and vulnerability scanning should be conducted to identify any remaining unpatched systems within the organization's attack surface.