CVE-2015-6177 in Office
Summary
by MITRE
Microsoft Excel 2007 SP3, 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 • 06/29/2022
The vulnerability identified as CVE-2015-6177 represents a critical memory corruption flaw within Microsoft Excel 2007 SP3, the Office Compatibility Pack SP3, and Excel Viewer applications. This weakness enables remote attackers to execute arbitrary code on affected systems through the careful manipulation of Office document structures. The vulnerability stems from improper handling of memory operations when processing specially crafted Office files, creating opportunities for malicious actors to gain unauthorized system access and potentially establish persistent footholds within target networks. The flaw exists in the way these applications parse and render specific document elements, particularly those involving complex data structures and formatting components that trigger buffer overflows or other memory management errors.
From a technical perspective, this vulnerability operates as a memory corruption issue that aligns with CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds write operations. The attack vector typically involves sending malicious Office documents through email attachments, web downloads, or compromised websites to unsuspecting users. When victims open these crafted files, the vulnerable Excel applications attempt to process malformed data structures that cause memory corruption, leading to unpredictable behavior including code execution. The exploitation process often leverages stack-based buffer overflows or heap corruption techniques that allow attackers to overwrite critical memory locations with malicious code payloads. This type of vulnerability is particularly dangerous because it can be triggered through simple document opening actions without requiring user interaction beyond the initial file access.
The operational impact of CVE-2015-6177 extends far beyond individual system compromise, as it enables attackers to establish persistent access to corporate networks through initial compromise points. Once successful, attackers can deploy additional malware, conduct data exfiltration, perform lateral movement, or use the compromised system as a launchpad for broader network attacks. The vulnerability's remote execution capability means that attackers do not need physical access to target systems, making it particularly attractive for large-scale campaign targeting. Organizations with extensive Excel usage patterns face heightened risk since these applications are commonly used across business environments for data analysis, reporting, and collaboration. The attack surface expands significantly when considering that users may unknowingly open malicious files from legitimate sources, making social engineering components of attacks particularly effective. Security teams must also account for the difficulty in detecting such attacks, as they often appear as normal document processing operations until the malicious code executes.
Mitigation strategies for CVE-2015-6177 require immediate implementation of Microsoft security patches and updates, as the vendor released specific fixes addressing the memory corruption issues in affected Excel versions. Organizations should implement strict document handling policies that limit the opening of external Office files, particularly those received through email or downloaded from untrusted sources. Network-based protections including email filtering systems, web proxies, and application control measures can help prevent initial access to malicious documents. Security monitoring should focus on detecting unusual Excel process behaviors, memory access patterns, and network connections that may indicate exploitation attempts. The implementation of principle of least privilege access controls, regular system updates, and user education programs can significantly reduce the likelihood of successful exploitation. Additionally, organizations should consider deploying advanced endpoint protection solutions that can detect and block known malicious file patterns and exploit techniques. Regular vulnerability assessments and penetration testing help identify potential attack vectors while maintaining awareness of emerging threats targeting similar memory corruption vulnerabilities. The ATT&CK framework categorizes this type of vulnerability under the T1059 technique for command and scripting interpreter, where attackers leverage compromised systems to execute malicious code through legitimate software applications.