CVE-2020-17062 in Office
Summary
by MITRE • 11/11/2020
Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability
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Analysis
by VulDB Data Team • 12/05/2020
The Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability represents a critical security flaw that affects numerous Microsoft Office applications and services. This vulnerability resides within the Access Connectivity Engine component that handles database connections and file processing operations, making it a prime target for attackers seeking to exploit remote execution capabilities. The flaw manifests when the engine processes specially crafted database files or connection strings, potentially allowing unauthorized code execution on affected systems. Security researchers identified this vulnerability through extensive analysis of the engine's parsing mechanisms and input validation procedures, which fail to properly sanitize user-supplied data before processing. The vulnerability impacts various Microsoft Office versions including Office 2016, Office 2019, and Office 2021, as well as Microsoft Access 2016 and Access 2019. This represents a significant concern for enterprise environments where Office applications are extensively used for data processing and database operations.
The technical implementation of this vulnerability stems from improper memory handling within the Access Connectivity Engine's database processing functions. When the engine encounters malformed or malicious database connection strings, it fails to validate input parameters adequately, leading to buffer overflows or memory corruption conditions. Attackers can craft specific database files or connection strings that trigger these memory handling flaws, resulting in arbitrary code execution with the privileges of the affected user. The vulnerability is classified as a remote code execution flaw that operates through network-based attacks without requiring user interaction for initial exploitation. This type of vulnerability typically falls under CWE-121, which describes heap-based buffer overflow conditions, and may also relate to CWE-787, representing out-of-bounds write conditions. The attack vector involves sending malicious database files or connection strings to systems running vulnerable versions of Office, making it particularly dangerous for organizations that process external database connections or receive database files from untrusted sources.
The operational impact of this vulnerability extends far beyond simple exploitation, as it provides attackers with persistent access to compromised systems and potentially enables further lateral movement within networks. Once executed, the malicious code can establish backdoors, exfiltrate sensitive data, or serve as a foothold for more extensive attacks. Organizations using Microsoft Office for database operations face elevated risk, particularly those that process external database connections or receive database files from partners, vendors, or public sources. The vulnerability's remote nature means that attackers can exploit it from anywhere on the internet without requiring physical access to target systems. This characteristic aligns with ATT&CK technique T1203, which describes exploitation for execution, and T1071.004, covering application layer protocol usage for command and control communications. The vulnerability affects not just individual users but entire enterprise environments where Office applications are used for database connectivity, making it a critical concern for IT security teams responsible for protecting organizational assets.
Mitigation strategies for this vulnerability require immediate patch deployment from Microsoft, as the company released security updates specifically addressing the flaw in their regular security bulletins. Organizations should prioritize updating all affected Office installations to the latest versions, ensuring that all users have the necessary security patches applied. Network segmentation and firewall rules can help limit the potential impact by restricting database connection access to trusted sources and implementing strict access controls. Security monitoring should focus on identifying unusual database connection patterns or file processing activities that might indicate exploitation attempts. Additionally, organizations should implement application whitelisting policies to restrict execution of unauthorized database processing applications. Regular security assessments and vulnerability scanning should include checks for outdated Office versions that may still be vulnerable. The vulnerability's classification as a critical issue by Microsoft indicates that organizations should treat it with high priority in their security response plans, as the potential for widespread exploitation exists given the prevalence of Office applications in enterprise environments.