Detection rules › Sigma

New Root Certificate Installed Via Certutil.EXE

Severity
medium
Author
oscd.community, @redcanary, Zach Stanford @svch0st
Source
upstream

Detects execution of "certutil" with the "addstore" flag in order to install a new certificate on the system. Adversaries may install a root certificate on a compromised system to avoid warnings when connecting to adversary controlled web servers.

MITRE ATT&CK coverage

TacticTechniques
Defense EvasionT1553.004 Subvert Trust Controls: Install Root Certificate

Event coverage

ProviderEvent IDTitle
Sysmon1Process creation

Stages and Predicates

Stage 1: all of selection_img

or:
Image|endswith: '\certutil.exe'
OriginalFileName: CertUtil.exe

Stage 2: all of selection_cli_add

CommandLine|contains: -addstore

Stage 3: all of selection_cli_store

CommandLine|contains: root

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.

FieldKindValues
CommandLinematch
  • -addstore
  • root corpus 2 (sigma 2)
Imageends_with
  • \certutil.exe corpus 34 (sigma 34)
OriginalFileNameeq
  • CertUtil.exe corpus 13 (sigma 13)