Malicious PowerShell Base64 Exfiltration to save.php via EKZ Stealer

ATT&CK techniques

Exfiltration

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
- T1041Exfiltration Over C2 Channel
Impact

What it detects

This rule detects PowerShell posting data with UploadString to a save.php endpoint, the exfiltration channel used by the EKZ Stealer following Fortinet exploitation. Base64-encoded stolen data including credentials is sent to the attacker web handler. Outbound UploadString calls to a save.php target strongly indicate data theft over the C2 channel.

Reporting behind it

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Malicious PowerShell Base64 Exfiltration to save.php via EKZ Stealer

Pivot detection · T1041 · 9 related

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