Visual Basic
Visual Basic [T1059.005]
Information
Introduction
Visual Basic (VB) scripting, identified as sub-technique T1059.005 in the MITRE ATT&CK framework, refers to adversaries employing VB scripts to execute malicious commands or payloads on targeted systems. Visual Basic scripts are commonly used due to their native support on Windows systems, ease of use, and capability to interact seamlessly with various Windows components. Attackers leverage VB scripts to automate execution, evade detection, and perform various malicious activities, including persistence, lateral movement, and command-and-control (C2) communication.
Deep Dive Into Technique
Visual Basic scripts (VBS) are plain-text scripts executed by the Windows Script Host (WSH) environment, which includes tools such as wscript.exe and cscript.exe. Attackers exploit these built-in Windows utilities to execute malicious scripts without invoking external binaries, thus reducing suspicion.
Technical details include:
Execution Methods:
Direct invocation using
wscript.exeorcscript.exefrom command-line or batch scripts.Embedding VB scripts within Office documents (macros) to execute malicious payloads upon user interaction.
Utilizing scripts stored in registry keys or scheduled tasks to establish persistence.
Common Mechanisms:
Leveraging VB scripts for reconnaissance, such as enumerating system information, network shares, and installed software.
Downloading additional payloads from remote servers using built-in objects like
XMLHTTPorWinHttpRequest.Encoding or obfuscating scripts (e.g., Base64 encoding, string concatenation, character substitution) to evade signature-based detection mechanisms.
Using COM objects for direct interaction with Windows APIs, enabling attackers to manipulate system settings, execute commands, or manage processes.
Real-world Procedures:
Attackers frequently embed malicious VB scripts within phishing emails or compromised websites, enticing users to execute malicious macros or scripts.
Malicious scripts are often deployed in targeted attacks via spear-phishing campaigns, exploiting user trust and lack of security awareness.
Advanced persistent threat (APT) actors utilize VB scripts for stealthy execution and persistence due to their low detection profile and native Windows integration.
When this Technique is Usually Used
Attack scenarios and stages where Visual Basic scripting is commonly utilized include:
Initial Access and Delivery:
Malicious email attachments (e.g., Office documents with embedded VB macros).
Drive-by downloads from compromised websites.
Execution and Persistence:
Establishing persistent footholds through scheduled tasks or registry modifications.
Automating execution of secondary payloads after initial compromise.
Defense Evasion:
Using obfuscated or encoded VB scripts to avoid detection by antivirus and endpoint detection and response (EDR) solutions.
Leveraging legitimate Windows scripting hosts (
wscript.exe,cscript.exe) to blend with normal system behavior.
Lateral Movement and Privilege Escalation:
Executing VB scripts remotely via Windows Management Instrumentation (WMI) or PowerShell remoting.
Utilizing scripts to exploit vulnerabilities or misconfigurations to escalate privileges or move laterally within the network.
Command-and-Control (C2):
Establishing communication channels with attacker-controlled servers using HTTP/HTTPS requests via VB scripts.
Periodically polling remote servers for commands or exfiltrating data through encoded HTTP requests.
How this Technique is Usually Detected
Detection methods and tools commonly employed to identify malicious Visual Basic scripting include:
Endpoint Detection and Response (EDR) Solutions:
Monitoring execution of
wscript.exeandcscript.exeprocesses, especially when invoked from unusual locations or with uncommon command-line parameters.Detecting anomalous script execution patterns, such as frequent or unusual script file extensions (
.vbs,.vbe).
Behavioral Analysis:
Identifying suspicious behaviors, including scripts downloading files from unknown external sources or executing encoded commands.
Observing scripts modifying registry keys, creating scheduled tasks, or interacting with COM objects in unusual ways.
Process Monitoring and Logging:
Collecting and analyzing Windows Event Logs, Sysmon logs, and process execution logs for unusual script execution.
Tracking command-line arguments passed to scripting hosts to detect encoded or obfuscated payloads.
Network Monitoring:
Detecting outbound HTTP/HTTPS requests initiated by VB scripts to unknown or suspicious domains.
Monitoring unusual traffic patterns indicative of C2 communication or data exfiltration attempts.
Specific Indicators of Compromise (IoCs):
Presence of unusual VB script files in temporary directories or user profile folders.
Registry modifications or scheduled tasks associated with script execution.
Known malicious script content or signatures identified through file analysis or threat intelligence feeds.
Why it is Important to Detect This Technique
Detecting malicious Visual Basic scripting is critical due to its potential impact on systems and networks:
System Compromise and Data Breach:
Attackers can use VB scripts to download and execute secondary payloads, leading to full system compromise or sensitive data exfiltration.
Persistence and Long-term Access:
Malicious scripts can establish persistent footholds, allowing attackers to maintain long-term access and control over compromised systems.
Difficulty in Attribution and Detection:
VB scripts executed via legitimate Windows utilities may evade traditional antivirus detection, complicating incident response and attribution.
Privilege Escalation and Lateral Movement:
Attackers can leverage scripts to escalate privileges or move laterally within networks, potentially compromising critical infrastructure or sensitive resources.
Early Detection and Mitigation:
Prompt identification and response to malicious VB script execution can significantly reduce the scope and impact of security incidents.
Early detection prevents attackers from establishing persistence or escalating privileges, limiting overall damage and remediation costs.
Examples
Real-world examples demonstrating the use of malicious Visual Basic scripting include:
Emotet Malware Campaign:
Attackers distributed malicious Microsoft Word documents containing VB macros via phishing emails.
Upon execution, macros downloaded and executed the Emotet banking trojan, leading to credential theft and further malware infections.
TrickBot Banking Trojan:
VB scripts embedded within malicious Excel documents executed upon enabling macros, downloading TrickBot payloads from remote servers.
Attackers utilized TrickBot to steal banking credentials, execute ransomware, and enable lateral movement across compromised networks.
APT32 (OceanLotus) Campaign:
Targeted attacks leveraged VB scripts embedded in Office documents to execute payloads silently.
Scripts performed reconnaissance, downloaded additional malware, and established persistent backdoors for espionage activities.
FIN7 Financially Motivated Attacks:
Attackers utilized VB scripts within spear-phishing emails targeting retail and hospitality sectors.
Scripts executed PowerShell commands, downloaded payloads, and facilitated lateral movement, resulting in significant financial losses.
QakBot (Qbot) Malware:
Malicious VB scripts embedded in phishing emails executed payloads that downloaded QakBot malware.
QakBot facilitated credential theft, lateral movement, and ransomware deployment, causing substantial operational disruptions.
These examples highlight the versatility of Visual Basic scripting as a tool leveraged by threat actors across various attack scenarios, emphasizing the importance of robust detection and mitigation strategies.
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