LoFP LoFP / security testing may produce events like this. activity of this kind performed by non-engineers and ordinary users is unusual.

Techniques

Sample rules

Network Connection via Registration Utility

Description

Identifies the native Windows tools regsvr32.exe, regsvr64.exe, RegSvcs.exe, or RegAsm.exe making a network connection. This may be indicative of an attacker bypassing allowlists or running arbitrary scripts via a signed Microsoft binary.

Detection logic

sequence by process.entity_id
  [process where host.os.type == "windows" and event.type == "start" and
   process.name : ("regsvr32.exe", "RegAsm.exe", "RegSvcs.exe") and
   not (
         (?process.Ext.token.integrity_level_name : "System" or ?winlog.event_data.IntegrityLevel : "System") and
         (process.parent.name : "msiexec.exe" or process.parent.executable : ("C:\\Program Files (x86)\\*.exe", "C:\\Program Files\\*.exe"))
       )
   ]
  [network where host.os.type == "windows" and process.name : ("regsvr32.exe", "RegAsm.exe", "RegSvcs.exe")  and
   not cidrmatch(destination.ip, "10.0.0.0/8", "127.0.0.0/8", "169.254.0.0/16", "172.16.0.0/12", "192.0.0.0/24",
       "192.0.0.0/29", "192.0.0.8/32", "192.0.0.9/32", "192.0.0.10/32", "192.0.0.170/32", "192.0.0.171/32",
       "192.0.2.0/24", "192.31.196.0/24", "192.52.193.0/24", "192.168.0.0/16", "192.88.99.0/24", "224.0.0.0/4",
       "100.64.0.0/10", "192.175.48.0/24","198.18.0.0/15", "198.51.100.0/24", "203.0.113.0/24", "240.0.0.0/4", "::1",
       "FE80::/10", "FF00::/8") and network.protocol != "dns"]