Suspicious PowerShell String Concatenation Obfuscation for Batch Extension via LNK (via process_creation)

ATT&CK techniques

Execution → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
- T1059.001PowerShell
- T1204.002Malicious File
Persistence
Priv Esc
Defense Evasion
- T1027Obfuscated Files or Information
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects PowerShell command lines that split the "bat" extension into concatenated string fragments to evade static detection, a technique observed in the APT37 ToyBox Story campaign delivering RoKRAT via malicious LNK files. It captures the obfuscation used to reconstruct a batch loader name at runtime so that command inspection does not reveal the dropped payload. Detecting this hidden concatenation surfaces the initial LNK-driven execution stage before the staged loaders run.

Reporting behind it

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Suspicious PowerShell String Concatenation Obfuscation for Batch Extension via LNK (via process_creation)

Pivot detection · T1059.001 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

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