CVE-2016-7263 in Office
Summary
by MITRE
Microsoft Excel for Mac 2011 and Excel 2016 for Mac allow remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted document, aka "Microsoft Office Memory Corruption Vulnerability."
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Analysis
by VulDB Data Team • 10/08/2022
The vulnerability identified as CVE-2016-7263 represents a critical memory corruption flaw affecting Microsoft Excel for Mac versions 2011 and 2016. This vulnerability resides within the spreadsheet application's handling of specially crafted document formats, creating an attack surface that adversaries can exploit to gain unauthorized system access or disrupt normal operations. The flaw manifests when Excel processes malformed or maliciously constructed spreadsheet files, leading to unpredictable memory behavior that can be leveraged for remote code execution or system instability. Security researchers have classified this issue under the Common Weakness Enumeration framework as a memory corruption vulnerability, specifically categorized under CWE-125, which describes out-of-bounds read conditions that can lead to arbitrary code execution. The attack vector requires an unsuspecting user to open a maliciously crafted Excel document, making social engineering a critical component of successful exploitation attempts. This vulnerability aligns with ATT&CK technique T1203, which covers exploitation for execution through manipulation of application execution flows. The memory corruption occurs during the parsing of specific data structures within Excel's document processing engine, where improper input validation allows attackers to manipulate memory pointers and execute malicious code within the application context. This flaw particularly affects users running Microsoft Office for Mac, which operates on different codebases than Windows versions, creating unique attack surfaces that require specialized exploitation techniques.
The operational impact of CVE-2016-7263 extends beyond simple denial of service conditions to encompass full system compromise capabilities for skilled attackers. When successfully exploited, the vulnerability enables remote code execution with the privileges of the currently logged-in user, potentially allowing attackers to install malware, modify system configurations, or exfiltrate sensitive data. The memory corruption aspect means that system stability is compromised, leading to application crashes or system-wide instability that can disrupt business operations. Organizations relying on Excel for Mac for critical business functions face significant risk exposure, particularly in environments where users frequently handle external spreadsheet documents or receive files from untrusted sources. The vulnerability's exploitation requires minimal user interaction beyond opening the malicious document, making it particularly dangerous in targeted attack scenarios. Security professionals have noted that this flaw can be particularly challenging to detect through traditional network monitoring tools since the malicious activity occurs locally within the user's application environment rather than through network-based attacks. The vulnerability's presence in both Excel 2011 and 2016 for Mac indicates a persistent flaw in Microsoft's document parsing libraries that affected multiple versions of the software, requiring comprehensive patch management strategies across affected deployments.
Mitigation strategies for CVE-2016-7263 must address both immediate defensive measures and long-term security enhancements. Microsoft released patches to address this vulnerability, and organizations should prioritize immediate deployment of these updates across all affected systems. Security administrators should implement strict document handling policies that restrict the opening of external spreadsheet files, particularly those from untrusted sources, while also considering the deployment of application control solutions that can prevent execution of malicious code. Network segmentation and endpoint protection measures should be enhanced to detect and block suspicious document processing activities that may indicate exploitation attempts. Organizations should also consider implementing email filtering solutions that can identify and quarantine potentially malicious Excel documents before they reach end users. The remediation process requires careful testing of patches to ensure compatibility with existing business applications and workflows, as updates may introduce unexpected behavior in legacy systems. Security monitoring should include detection of anomalous memory usage patterns and unexpected application crashes that may indicate exploitation attempts. Additionally, user education programs should emphasize the dangers of opening unexpected spreadsheet files and the importance of verifying document sources before processing. From a compliance perspective, organizations should document their remediation efforts and maintain audit trails demonstrating due diligence in addressing this vulnerability. The vulnerability also highlights the importance of maintaining up-to-date security patches across all Microsoft Office for Mac installations, as similar memory corruption flaws may exist in other components of the Office suite. Regular vulnerability assessments and penetration testing should be conducted to identify additional attack surfaces that may be susceptible to similar exploitation techniques.