DLL Sideloading by VMware Xfer Utility

About the rule

Rule Type

Standard

Rule Description

VMwareXferUtility.exe is a legitimate utility bundled with various VMware products, often used for file transfers or virtual machine operations. Threat actors can abuse this trusted binary to perform Dynamic Link Library (DLL) sideloading by placing a maliciously crafted DLL in a directory where VMwareXferUtility.exe loads it during execution. This technique enables attackers to run arbitrary code under the guise of a trusted process, bypassing some security controls and improving stealth.

Severity

Trouble

Rule journey

Attack chain scenario

Initial access → malicious DLL dropped → VMwareXferUtility.exe launched → DLL sideloading abuse → Impact

Impact

• Defense evasion
• Stealthy malware execution
• Privilege escalation
• System persistence
• Data exfiltration

Rule Requirement

Prerequisites

Use the Group Policy Management Console to audit process creation and process termination.

Install Sysmon from Microsoft Sysinternals and download the Sysmon configuration file that includes process creation monitoring. Add network connection events to the configuration file to monitor all network activity.

Create a new registry key "Microsoft-Windows-Sysmon/Operational" in the directory "Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\EventLog\" if not already created.

Criteria

Detection

Execution Mode

realtime

Log Sources

Windows

MITRE ATT&CK

Defense Evasion: Hijack Execution Flow - DLL Side-Loading (T1574.002), Persistence: Hijack Execution Flow - DLL Side-Loading (T1574.002), Privilege Escalation: Hijack Execution Flow - DLL Side-Loading (T1574.002)

Security Standards

Enabling this rule will help you meet the security standard's requirement listed below:

DE.CM-01: Networks and network services are monitored to find potentially adverse events.

When this rule is triggered, you are notified when VMwareXferUtility.exe loads a DLL from an unexpected or suspicious directory, facilitating the detection and investigation of DLL sideloading attempts. This enables you to examine binary and DLL trust relationships, review execution chains, and identify malicious code execution under the cover of legitimate VMware activities, supporting proactive defense and rapid response.

DE.CM-09: Computing hardware and software, runtime environments, and their data are monitored to find potentially adverse events.

Sideloaded DLLs represent unauthorized code execution. Detection of such events in the runtime environment and prompting a rapid response directly aligns to this objective.

Author

Nasreddine Bencherchali (Nextron Systems)

Future actions

Known False Positives

This rule may trigger on legitimate plugin extensions or custom deployments where VMwareXferUtility.exe loads third-party or corporate-developed DLLs. Carefully review the DLL path, signing status, and parent-child process relationship for legitimacy.

Next Steps

When this rule is triggered, the following measures can be implemented:

1. Identification: Identify if the flagged event is a new incident or part of an existing incident.
2. Analysis: Analyze the impact and extent of the incident to comprehend the severity of the attack using the Incident Workbench.
3. Response: Respond promptly by initiating an automated workflow to interrupt the network connections and cease the malicious process.
4. Reconfiguration: Update allowlists for authorized DLLs, tune detection logic for legitimate cases, and audit VMware deployments for signs of lateral movement or persistence techniques.

Mitigation