Detection rules › Sigma
Suspicious Curl File Upload - Linux
Detects a suspicious curl process start the adds a file to a web request
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Command & Control | T1105 Ingress Tool Transfer |
| Exfiltration | T1567 Exfiltration Over Web Service |
Event coverage
| Provider | Event |
|---|---|
| Sysmon-for-Linux | Event ID 1 |
Rule body yaml
title: Suspicious Curl File Upload - Linux
id: 00b90cc1-17ec-402c-96ad-3a8117d7a582
related:
- id: 00bca14a-df4e-4649-9054-3f2aa676bc04
type: derived
status: test
description: Detects a suspicious curl process start the adds a file to a web request
references:
- https://twitter.com/d1r4c/status/1279042657508081664
- https://medium.com/@petehouston/upload-files-with-curl-93064dcccc76
- https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1105/T1105.md#atomic-test-19---curl-upload-file
- https://curl.se/docs/manpage.html
- https://www.trendmicro.com/en_us/research/22/i/how-malicious-actors-abuse-native-linux-tools-in-their-attacks.html
author: Nasreddine Bencherchali (Nextron Systems), Cedric MAURUGEON (Update)
date: 2022-09-15
modified: 2023-05-02
tags:
- attack.exfiltration
- attack.command-and-control
- attack.t1567
- attack.t1105
logsource:
category: process_creation
product: linux
detection:
selection_img:
Image|endswith: '/curl'
selection_cli:
- CommandLine|contains:
- ' --form' # Also covers the "--form-string"
- ' --upload-file '
- ' --data '
- ' --data-' # For flags like: "--data-ascii", "--data-binary", "--data-raw", "--data-urlencode"
- CommandLine|re: '\s-[FTd]\s' # We use regex to ensure a case sensitive argument detection
filter_optional_localhost:
CommandLine|contains:
- '://localhost'
- '://127.0.0.1'
condition: all of selection_* and not 1 of filter_optional_*
falsepositives:
- Scripts created by developers and admins
level: medium
Stages and Predicates
Stage 0: condition
all of selection_* and not 1 of filter_optional_*Stage 1: selection_img
selection_img:
Image|endswith: '/curl'
Stage 2: selection_cli
selection_cli:
- CommandLine|contains:
- ' --form'
- ' --upload-file '
- ' --data '
- ' --data-'
- CommandLine|re: '\s-[FTd]\s'
Stage 3: not filter_optional_localhost
filter_optional_localhost:
CommandLine|contains:
- '://localhost'
- '://127.0.0.1'
Exclusions
Top-level NOT(...) conjuncts: predicates this rule actively suppresses.
| Field | Kind | Excluded values |
|---|---|---|
CommandLine | match | ://127.0.0.1 |
CommandLine | match | ://localhost |
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 |
|
CommandLine | regex_match |
|
Image | ends_with |
|