Regsvr32 Execution From Potential Suspicious Location

Severity: medium
Author: Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
Source: upstream

Detects execution of regsvr32 where the DLL is located in a potentially suspicious location.

MITRE ATT&CK coverage

Tactic	Techniques
Defense Evasion	`T1218.010` System Binary Proxy Execution: Regsvr32

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `all of selection_img`

or:
Image|endswith: '\regsvr32.exe'
OriginalFileName: REGSVR32.EXE

Stage 2: `all of selection_cli`

or:
CommandLine|contains: ':\ProgramData\'
CommandLine|contains: ':\Temp\'
CommandLine|contains: ':\Users\Public\'
CommandLine|contains: ':\Windows\Temp\'
CommandLine|contains: '\AppData\Local\Temp\'
CommandLine|contains: '\AppData\Roaming\'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`CommandLine`	match	`:\ProgramData\` corpus 5 (sigma 5) `:\Temp\` corpus 14 (sigma 14) `:\Users\Public\` corpus 14 (sigma 14) `:\Windows\Temp\` corpus 15 (sigma 15) `\AppData\Local\Temp\` corpus 16 (sigma 16) `\AppData\Roaming\` corpus 10 (sigma 10)
`Image`	ends_with	`\regsvr32.exe` corpus 57 (sigma 57)
`OriginalFileName`	eq	`REGSVR32.EXE` corpus 10 (sigma 10)