CVE-2011-1980 in Office
Summary
by MITRE
Untrusted search path vulnerability in Microsoft Office 2003 SP3 and 2007 SP2 allows local users to gain privileges via a Trojan horse DLL in the current working directory, as demonstrated by a directory that contains a .doc, .ppt, or .xls file, aka "Office Component Insecure Library Loading Vulnerability."
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 03/19/2021
The vulnerability identified as CVE-2011-1980 represents a critical untrusted search path issue affecting Microsoft Office 2003 Service Pack 3 and Office 2007 Service Pack 2. This flaw stems from the insecure loading of dynamic link libraries within the Office application environment, creating a privilege escalation vector that adversaries can exploit through carefully crafted malicious files. The vulnerability specifically manifests when Office applications process documents containing embedded references to external libraries, allowing attackers to place malicious DLL files in the same directory as the targeted Office document. This behavior aligns with CWE-427, which describes uncontrolled search path dependencies, and demonstrates how applications fail to properly validate or sanitize library loading paths. The attack scenario involves placing a Trojan horse DLL file in the current working directory where the Office application is executing, enabling the malicious code to be loaded and executed with the privileges of the targeted user. This vulnerability directly impacts the principle of least privilege and demonstrates how insecure library loading practices can compromise system integrity.
The technical exploitation of this vulnerability occurs through the manipulation of Office's dynamic library loading mechanism, where applications search for required DLL files in a predetermined order that includes the current working directory. When an Office document is opened from a directory containing a malicious DLL with the same name as a legitimate library that the Office application expects to load, the system will load the attacker-controlled DLL instead of the legitimate one. This process represents a classic insecure library loading vulnerability that allows for arbitrary code execution with the privileges of the user running the Office application. The vulnerability affects multiple Office file formats including Word documents, PowerPoint presentations, and Excel spreadsheets, making it particularly dangerous as it can be triggered through various document types. The attack requires local system access and user interaction to open the malicious document, but once executed, it can provide persistent access to the compromised system. This exploitation pattern aligns with ATT&CK technique T1059.001 for command and scripting interpreter and T1068 for exploit for privilege escalation, demonstrating how insecure library loading can serve as a foundational attack vector for more sophisticated compromises.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it can serve as a foothold for broader system compromise within enterprise environments. Organizations with multiple users running affected Office versions face significant risk, as a single compromised document can lead to unauthorized access to sensitive corporate data. The vulnerability's exploitation is particularly concerning in environments where users frequently open documents from untrusted sources or shared network drives, as these locations often contain the necessary conditions for successful attack delivery. Security professionals should note that this vulnerability can be particularly challenging to detect and remediate, as the malicious DLL files can be disguised as legitimate components, and the attack may not immediately manifest as suspicious activity. The risk is compounded by the fact that many organizations may not have comprehensive visibility into all Office installations across their networks, potentially leaving some systems vulnerable to exploitation. This vulnerability highlights the importance of proper application security practices and demonstrates how seemingly minor implementation flaws can create significant security risks, particularly in enterprise environments where Office applications are widely deployed and frequently used across multiple user accounts and system configurations.
Mitigation strategies for CVE-2011-1980 should focus on both immediate remediation and long-term security hardening measures. Microsoft has addressed this vulnerability through security updates, and organizations should ensure all affected Office installations are updated with the latest security patches. Additionally, implementing security controls such as disabling automatic execution of macros, restricting file execution from network locations, and employing application whitelisting solutions can significantly reduce the attack surface. Network administrators should consider implementing strict file permissions and monitoring for unauthorized DLL file creation in directories containing Office documents. The use of sandboxing techniques for document processing and implementing security awareness training for end users can further reduce the risk of successful exploitation. Organizations should also consider deploying endpoint protection solutions that can detect and block suspicious library loading activities, particularly those involving DLL files loaded from unexpected or user-writable directories. These defensive measures align with security frameworks such as the NIST Cybersecurity Framework and can help organizations achieve compliance with various regulatory requirements while reducing their exposure to similar vulnerabilities. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date security patches and implementing robust application security practices to prevent exploitation of insecure library loading mechanisms.