mirror of
https://github.com/splunk/security_content
synced 2026-06-08 17:32:49 +00:00
mhaag-spl
91 lines
3.5 KiB
YAML
91 lines
3.5 KiB
YAML
name: CertUtil With Decode Argument
|
|
id: bfe94226-8c10-11eb-a4b3-acde48001122
|
|
version: 2
|
|
date: '2021-03-23'
|
|
author: Michael Haag, Splunk
|
|
type: TTP
|
|
datamodel:
|
|
- Endpoint
|
|
description: CertUtil.exe may be used to `encode` and `decode` a file, including PE
|
|
and script code. Encoding will convert a file to base64 with `-----BEGIN CERTIFICATE-----`
|
|
and `-----END CERTIFICATE-----` tags. Malicious usage will include decoding a encoded
|
|
file that was downloaded. Once decoded, it will be loaded by a parallel process.
|
|
Note that there are two additional command switches that may be used - `encodehex`
|
|
and `decodehex`. Similarly, the file will be encoded in HEX and later decoded for
|
|
further execution. During triage, identify the source of the file being decoded.
|
|
Review its contents or execution behavior for further analysis.
|
|
search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
|
|
as lastTime from datamodel=Endpoint.Processes where `process_certutil` Processes.process=*decode*
|
|
by Processes.dest Processes.user Processes.parent_process Processes.process_name
|
|
Processes.process Processes.process_id Processes.parent_process_id | `drop_dm_object_name(Processes)`
|
|
| `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `certutil_with_decode_argument_filter`'
|
|
how_to_implement: To successfully implement this search you need to be ingesting information
|
|
on process that include the name of the process responsible for the changes from
|
|
your endpoints into the `Endpoint` datamodel in the `Processes` node. In addition,
|
|
confirm the latest CIM App 4.20 or higher is installed and the latest TA for the
|
|
endpoint product.
|
|
known_false_positives: Typically seen used to `encode` files, but it is possible to
|
|
see legitimate use of `decode`. Filter based on parent-child relationship, file
|
|
paths, endpoint or user.
|
|
references:
|
|
- https://attack.mitre.org/techniques/T1140/
|
|
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1140/T1140.md
|
|
- https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/certutil
|
|
- https://www.bleepingcomputer.com/news/security/certutilexe-could-allow-attackers-to-download-malware-while-bypassing-av/
|
|
tags:
|
|
analytic_story:
|
|
- Deobfuscate-Decode Files or Information
|
|
- Living Off The Land
|
|
confidence: 80
|
|
context:
|
|
- Source:Endpoint
|
|
- Stage:Execution
|
|
dataset:
|
|
- https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1140/atomic_red_team/windows-sysmon.log
|
|
impact: 50
|
|
kill_chain_phases:
|
|
- Exploitation
|
|
message: An instance of $parent_process_name$ spawning $process_name$ was identified
|
|
on endpoint $dest$ by user $user$ attempting to decode a file.
|
|
mitre_attack_id:
|
|
- T1140
|
|
observable:
|
|
- name: user
|
|
type: User
|
|
role:
|
|
- Victim
|
|
- name: dest
|
|
type: Hostname
|
|
role:
|
|
- Victim
|
|
- name: parent_process_name
|
|
type: Process
|
|
role:
|
|
- Parent Process
|
|
- name: process_name
|
|
type: Process
|
|
role:
|
|
- Child Process
|
|
product:
|
|
- Splunk Enterprise
|
|
- Splunk Enterprise Security
|
|
- Splunk Cloud
|
|
required_fields:
|
|
- _time
|
|
- Processes.dest
|
|
- Processes.user
|
|
- Processes.parent_process_name
|
|
- Processes.parent_process
|
|
- Processes.original_file_name
|
|
- Processes.process_name
|
|
- Processes.process
|
|
- Processes.process_id
|
|
- Processes.parent_process_path
|
|
- Processes.process_path
|
|
- Processes.parent_process_id
|
|
risk_score: 40
|
|
security_domain: endpoint
|
|
supported_tas:
|
|
- Splunk_TA_microsoft_sysmon
|
|
asset_type: Endpoint
|