CVE-2015-2521 in Excel
Summary
by MITRE
Microsoft Excel 2007 SP3, Excel 2010 SP2, Office Compatibility Pack SP3, and Excel Viewer allow remote attackers to execute arbitrary code via a crafted Office document, aka "Microsoft Office Memory Corruption Vulnerability."
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Analysis
by VulDB Data Team • 06/24/2024
The vulnerability identified as CVE-2015-2521 represents a critical memory corruption flaw within Microsoft Excel applications and the Office Compatibility Pack that enables remote code execution through maliciously crafted Office documents. This vulnerability affects multiple versions including Excel 2007 SP3, Excel 2010 SP2, and the Office Compatibility Pack SP3, making it particularly widespread across enterprise environments that rely on legacy Office installations. The flaw resides in how these applications handle specific data structures within Office document formats, creating opportunities for attackers to manipulate memory operations and ultimately gain unauthorized execution privileges on affected systems.
The technical implementation of this vulnerability stems from improper input validation and memory handling within Excel's document parsing mechanisms. When processing specially crafted Office documents, the application fails to properly validate memory boundaries and data structures, leading to buffer overflows or other memory corruption conditions. This type of vulnerability maps directly to CWE-121, which describes heap-based buffer overflow conditions, and CWE-125, which addresses out-of-bounds read errors that can lead to memory corruption. Attackers can exploit this weakness by creating malicious documents that trigger specific parsing sequences within Excel, causing the application to execute arbitrary code with the privileges of the user running the vulnerable software.
The operational impact of CVE-2015-2521 extends far beyond individual system compromise, as it represents a significant threat to enterprise security infrastructure. Organizations running affected versions of Excel face potential full system compromise when users open malicious documents, either through email attachments, web downloads, or file sharing mechanisms. The vulnerability's remote exploitation capability means that attackers do not require physical access to target systems, making it particularly dangerous in networked environments where users frequently interact with external content. This flaw can be leveraged as an initial access vector in broader attack campaigns, potentially leading to lateral movement within networks, data exfiltration, and persistent backdoor establishment.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security posture improvements. Microsoft released security patches through regular updates that address the memory corruption issues within affected Excel versions, requiring organizations to implement timely patch management processes. Security controls should include email filtering solutions that can detect and block malicious Office documents, application whitelisting policies that restrict execution of untrusted Office files, and user education programs to reduce the likelihood of opening suspicious attachments. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1059 for command and script interpreter execution and T1203 for exploitation for client execution, making it a critical target for defensive measures that monitor for anomalous Office process behavior and suspicious memory access patterns. Organizations should also consider implementing network segmentation and endpoint detection systems that can identify and block exploitation attempts targeting this specific vulnerability.