Detect JavaScript in Google Chronicle
Adversaries may abuse various implementations of JavaScript for execution. JavaScript (JS) is a platform-independent scripting language commonly associated with web pages, but can also execute in runtime environments outside the browser. JScript is Microsoft's implementation interpreted via the Windows Script engine. JavaScript for Automation (JXA) is a macOS scripting language based on JavaScript, included in Apple's Open Scripting Architecture. Adversaries abuse JS for drive-by compromises, malicious email attachments (.js files), HTA-based payloads, and post-exploitation on macOS via JXA. Threat actors including APT32, TA505, Contagious Interview, and FIN6 use JavaScript extensively.
MITRE ATT&CK
- Tactic
- Execution
- Technique
- T1059 Command and Scripting Interpreter
- Sub-technique
- T1059.007 JavaScript
- Canonical reference
- https://attack.mitre.org/techniques/T1059/007/
YARA-L Detection Query
rule t1059_007_javascript_abuse {
meta:
author = "Argus Detection Engineering"
description = "Detects JavaScript interpreter abuse via wscript.exe, cscript.exe, mshta.exe, node.exe, or osascript with suspicious command-line patterns. Covers JScript, Node.js, and macOS JXA execution vectors used by threat actors including APT32, TA505, and FIN6."
mitre_attack_tactic = "Execution"
mitre_attack_technique = "T1059.007"
severity = "HIGH"
priority = "HIGH"
events:
$e.metadata.event_type = "PROCESS_LAUNCH"
$e.principal.process.file.full_path = /(?i)(wscript\.exe|cscript\.exe|mshta\.exe|node\.exe|osascript)$/
(
$e.principal.process.command_line = /(?i)\.(js|jse|wsf|hta)(\s|"|'|$)/ or
$e.principal.process.command_line = /(?i)(activexobject|wscript\.createobject|getobject)/ or
$e.principal.process.command_line = /(?i)(wscript\.shell|shell\.application)/ or
$e.principal.process.command_line = /(?i)(adodb\.stream|msxml2\.xmlhttp|winhttp\.winhttprequest)/ or
$e.principal.process.command_line = /(?i)(eval\(|new function\(|runhtmlapplication)/ or
$e.principal.process.command_line = /(?i)(certutil|bitsadmin|powershell|cmd\.exe|cmd\s+\/c)/ or
$e.principal.process.command_line = /(?i)(-l javascript|scriptengine|javascript:)/
)
condition:
$e
}Chronicle YARA-L 2.0 rule detecting JavaScript interpreter abuse across all major execution vectors — JScript via wscript/cscript, MSHTA-based payloads, Node.js execution, and macOS JXA via osascript — with pattern matching on command-line indicators associated with T1059.007 threat actor TTPs.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate business scripting using WScript or CScript for software deployment, network share enumeration, or Help Desk automation tools
- Node.js web frameworks such as Express or Electron-based desktop applications invoking shell commands for system interaction
- macOS developer workflows using osascript with JavaScript for Automator actions, Alfred workflows, or Raycast extensions
Other platforms for T1059.007
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1JScript Execution via wscript.exe
Expected signal: Sysmon Event ID 1: Process Create for wscript.exe executing .js file. Child process event for cmd.exe spawned by wscript.exe. AMSI Event: JScript content inspection.
- Test 2Node.js Command Execution
Expected signal: Sysmon Event ID 1: Process Create for node.exe with child_process in CommandLine. Child process event for cmd.exe spawned by node.exe.
- Test 3JXA Execution on macOS
Expected signal: Unified Log: osascript process with '-l JavaScript' flag. Process tree shows osascript spawning child process for whoami. MDE DeviceProcessEvents on managed macOS endpoints.
References (6)
- https://attack.mitre.org/techniques/T1059/007/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1059.007/T1059.007.md
- https://nodejs.org/
- https://posts.specterops.io/persistent-jxa-66e1c3cd1cf5
- https://redcanary.com/blog/clipping-silver-sparrows-wings/
- https://lolbas-project.github.io/
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