Sigma rule: Obfuscated IP Download Activity

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-8261883d3202, updated 2026-03-16T00:00:00.000Z.

Rule

Title
Obfuscated IP Download Activity
Status
test
Level
medium
Author
Florian Roth (Nextron Systems), X__Junior (Nextron Systems)
Date
2022-08-03
Modified
2026-03-16
File
rules/windows/process_creation/proc_creation_win_susp_obfuscated_ip_download.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects use of an encoded/obfuscated version of an IP address (hex, octal...) in an URL combined with a download command

Log source

product
windows
category
process_creation

Detection

selection_command:
    CommandLine|contains:
        - 'Invoke-WebRequest'
        - 'iwr '
        - 'Invoke-RestMethod'
        - 'irm '
        - 'wget '
        - 'curl '
        - 'DownloadFile'
        - 'DownloadString'
selection_ip_1:
    CommandLine|contains:
        - ' 0x'
        - '//0x'
        - '.0x'
        - '.00x'
selection_ip_2:
    CommandLine|contains|all:
        - 'http://%'
        - '%2e'
selection_ip_3:
    # http://81.4.31754
    - CommandLine|re: 'https?://[0-9]{1,3}\.[0-9]{1,3}\.0[0-9]{3,4}'
    # http://81.293898
    - CommandLine|re: 'https?://[0-9]{1,3}\.0[0-9]{3,7}'
    # http://1359248394
    - CommandLine|re: 'https?://0[0-9]{3,11}'
    # http://0121.04.0174.012
    - CommandLine|re: 'https?://(?:0[0-9]{1,11}\.){3}0[0-9]{1,11}'
    # http://012101076012
    - CommandLine|re: 'https?://0[0-9]{1,11}'
    # For octal format
    - CommandLine|re: ' [0-7]{7,13}'
filter_main_valid_ip:
    CommandLine|re: 'https?://(?:(?:25[0-5]|(?:2[0-4]|1\d|[1-9])?\d)(?:\.|\b)){4}'
condition: selection_command and 1 of selection_ip_* and not 1 of filter_main_*

False positives (as the rule lists them)

  • Unknown

Tags

  • attack.discovery

References

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

Sources and licences

  • SigmaHQ

    "Obfuscated IP Download Activity" by Florian Roth (Nextron Systems), X__Junior (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_susp_obfuscated_ip_download.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: Obfuscated IP Download Activity",
entity page, dataset version ref-8261883d3202, updated 2026-03-16T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/cb5a2333-56cf-4562-8fcb-22ba1bca728d (accessed 2026-11-03).
Underlying source: SigmaHQ rule cb5a2333-56cf-4562-8fcb-22ba1bca728d, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.