CVE-2016-7275 in Office
Summary
by MITRE
Microsoft Office 2010 SP2, 2013 SP1, 2013 RT SP1, and 2016 mishandles library loading, which allows local users to gain privileges via a crafted application, aka "Microsoft Office OLE DLL Side Loading Vulnerability."
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 10/08/2022
The Microsoft Office OLE DLL Side Loading Vulnerability represents a critical privilege escalation flaw affecting multiple versions of Microsoft Office including 2010 SP2, 2013 SP1, 2013 RT SP1, and 2016. This vulnerability stems from improper handling of dynamic link library loading mechanisms within the Office application suite, creating an exploitable condition that allows local attackers to elevate their privileges. The flaw specifically manifests during the loading process of OLE (Object Linking and Embedding) objects, where the application fails to properly validate or restrict the paths from which DLLs are loaded. This behavior aligns with CWE-427, which describes uncontrolled search path elements, and CWE-428, which addresses unquoted search paths, both of which are common vectors for DLL side-loading attacks.
The technical exploitation of this vulnerability occurs when a malicious application or document containing crafted OLE objects is executed within the context of a victim's Office environment. The Office application attempts to load required libraries through the standard Windows DLL search order, which prioritizes the current working directory before system directories. Attackers can leverage this by placing malicious DLL files in directories that are searched before legitimate system locations, causing the Office application to load and execute the attacker-controlled code with the privileges of the currently logged-in user. This attack vector is particularly dangerous because it does not require user interaction beyond opening a malicious document, and the privilege escalation occurs automatically during normal Office operation.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it can serve as a foundational attack primitive for more sophisticated exploitation chains. Once an attacker achieves privilege escalation, they can manipulate system settings, install additional malicious software, access sensitive data, or establish persistent access through various attack techniques. The vulnerability's presence across multiple Office versions creates widespread exposure, affecting organizations that maintain legacy systems or have delayed security updates. From an ATT&CK framework perspective, this vulnerability maps to T1068, which covers local privilege escalation, and T1546, which addresses event trigger exploitation. The vulnerability also demonstrates characteristics of T1197, which involves the use of the Windows Registry for persistence, as attackers may leverage the elevated privileges to establish malicious registry entries.
Organizations can mitigate this vulnerability through several defensive measures that align with established security best practices. The most effective immediate mitigation involves applying the relevant Microsoft security updates that address the DLL loading behavior and correct the improper library loading mechanisms. Additionally, implementing application control policies such as AppLocker or Software Restriction Policies can prevent unauthorized DLL execution by restricting which binaries can run on systems. The principle of least privilege should be enforced by running Office applications with reduced permissions and avoiding execution as administrator. System hardening measures including disabling unnecessary OLE functionality, implementing strict DLL search path policies, and monitoring for suspicious DLL loading events through Windows Event Logging can provide additional layers of defense. Network segmentation and endpoint detection and response solutions should be configured to monitor for indicators of compromise related to this vulnerability, including anomalous DLL loading patterns or attempts to place malicious files in system directories. The vulnerability also underscores the importance of maintaining current security patches and implementing comprehensive vulnerability management processes to prevent similar issues from arising in the future.