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Detection rules › Sigma

Insecure Transfer Via Curl.EXE

Status
test
Severity
medium
Log source
product windows, category process_creation
Author
X__Junior (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects execution of "curl.exe" with the "--insecure" flag.

MITRE ATT&CK coverage

TacticTechniques
ExecutionNo specific technique

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

title: Insecure Transfer Via Curl.EXE
id: cb9cc1d1-e84e-4bdc-b7ad-c31b1b7908ec
status: test
description: Detects execution of "curl.exe" with the "--insecure" flag.
references:
    - https://curl.se/docs/manpage.html
author: X__Junior (Nextron Systems)
date: 2023-06-30
tags:
    - attack.execution
logsource:
    product: windows
    category: process_creation
detection:
    selection_img:
        - Image|endswith: '\curl.exe'
        - OriginalFileName: 'curl.exe'
    selection_cli:
        - CommandLine|re: '\s-k\s'
        - CommandLine|contains: '--insecure'
    condition: all of selection_*
falsepositives:
    - Access to badly maintained internal or development systems
level: medium
regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_curl_insecure_connection/info.yml

Stages and Predicates

Stage 0: condition

all of selection_*

Stage 1: selection_img

selection_img:
    - Image|endswith: '\curl.exe'
    - OriginalFileName: 'curl.exe'

Stage 2: selection_cli

selection_cli:
    - CommandLine|re: '\s-k\s'
    - CommandLine|contains: '--insecure'

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
  • --insecure
CommandLineregex_match
  • \s-k\s
Imageends_with
  • \curl.exe corpus 30 (sigma 30)
OriginalFileNameeq
  • curl.exe corpus 15 (sigma 12, splunk 3)