Sigma rule: Suspicious Curl File Upload - Linux

Rule

Title

Suspicious Curl File Upload - Linux

Status

test

Level

medium

Author

Nasreddine Bencherchali (Nextron Systems), Cedric MAURUGEON (Update)

Date

2022-09-15

Modified

2023-05-02

File

rules/linux/process_creation/proc_creation_lnx_susp_curl_fileupload.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects a suspicious curl process start the adds a file to a web request

Log source

product

linux

category

process_creation

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_*

False positives (as the rule lists them)

• Scripts created by developers and admins

Tags

• attack.exfiltration
• attack.command-and-control
• attack.t1567
• attack.t1105

MITRE ATT&CK ids this rule names

• T1105
• T1567

Related rules

• 00bca14a-df4e-4649-9054-3f2aa676bc04 (derived)

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

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