Sigma rule: Potential Data Exfiltration Via Curl.EXE

Rule

Title

Potential Data Exfiltration Via Curl.EXE

Status

test

Level

medium

Author

Florian Roth (Nextron Systems), Cedric MAURUGEON (Update)

Date

2020-07-03

Modified

2023-05-02

File

rules-threat-hunting/windows/process_creation/proc_creation_win_curl_fileupload.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects the execution of the "curl" process with "upload" flags. Which might indicate potential data exfiltration

Log source

product

windows

category

process_creation

Detection

selection_img:
    - Image|endswith: '\curl.exe'
    - Product: 'The curl executable'
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_*

False positives (as the rule lists them)

• Scripts created by developers and admins

Tags

• attack.exfiltration
• attack.command-and-control
• attack.t1567
• attack.t1105
• detection.threat-hunting

MITRE ATT&CK ids this rule names

• T1105
• T1567

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

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-threat-hunting/windows/process_creation/proc_creation_win_curl_fileupload.yml