huntrule

Suspicious Windows regsvr32 Command-Line Uses FTP/HTTP to Register Remote Components

Alerts on regsvr32 command lines using /i flags with ftp/http content, consistent with remote DLL registration.

FreeReviewedSigma · Medium · v1
Product
windows
Category
process_creation
Author
Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2023-05-24
Updated
2026-07-30
AnalysisDetection

ATT&CK techniques

Defense Evasion

  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Priv Esc

  7. Defense Evasion

  8. Cred Access

  9. Discovery

  10. Lateral Movement

  11. Collection

  12. C2

  13. Exfiltration

  14. Impact

What it detects

This rule flags regsvr32.exe executions where the command line includes image registration flags ('/i' or ' -i') and references remote content over FTP or HTTP. Attackers may use regsvr32 to stealthily fetch and register attacker-controlled DLLs from network locations. It relies on Windows process creation telemetry, matching the process image and specific substrings within the command line.

Reporting behind it

Related detections9 linkedT1218.010 — drag to rearrange
Suspicious Script Host Spawning Regsvr32 via Strela Stealer JScript Loader (via process_creation)
Malicious DLL Registration via regsvr32 Loading prnfldr (via process_creation)
Suspicious Regsvr32 Execution of SafePay Loader DLL
Suspicious Scheduled Task Running Regsvr32 with Extreme Duration by StaryDobry
Malicious DynamicWrapperX Registration via regsvr32 (via process_creation)
Suspicious Run Key Persistence Executing regsvr32
Suspicious regsvr32 Registering DLL from User AppData
Malicious Regsvr32 Loading Masqueraded VPN DLL via Process Creation
Malicious Regsvr32 ShellExec_RunDLL Proxy Execution (via process_creation)
Suspicious Windows regsvr32 Command-Line Uses FTP/HTTP to Register Remote Components
Pivot detection · T1218.010 · 9 related

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