BITS Transfer Job With Uncommon Or Suspicious Remote TLD

SIGMA detection rule by Florian Roth (Nextron Systems) · NOASSERTION

Detects a suspicious download using the BITS client from a FQDN that is unusual. Adversaries may abuse BITS jobs to persistently execute or clean up after malicious payloads.

title: BITS Transfer Job With Uncommon Or Suspicious Remote TLD
id: 6d44fb93-e7d2-475c-9d3d-54c9c1e33427
status: test
description: Detects a suspicious download using the BITS client from a FQDN that is unusual. Adversaries may abuse BITS jobs to persistently execute or clean up after malicious payloads.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1197/T1197.md
    - https://twitter.com/malmoeb/status/1535142803075960832
author: Florian Roth (Nextron Systems)
date: 2022-06-10
modified: 2025-02-28
tags:
    - attack.persistence
    - attack.execution
    - attack.stealth
    - attack.t1197
logsource:
    product: windows
    service: bits-client
detection:
    selection:
        EventID: 16403
    filter_main_generic:
        RemoteName|contains:
            - '.azureedge.net/'
            - '.com/'
            - '.sfx.ms/'
            - 'download.mozilla.org/' # https://download.mozilla.org/?product=firefox-101.0.1-partial-101.0&amp;os=win64&amp;lang=en-US
            - 'cdn.onenote.net/'
            - 'cdn.office.net/'
            - 'tscdn.m365.static.microsoft/'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - This rule doesn't exclude other known TLDs such as ".org" or ".net". It's recommended to apply additional filters for software and scripts that leverage the BITS service
level: medium
regression_tests_path: regression_data/rules/windows/builtin/bits_client/win_bits_client_new_transfer_via_uncommon_tld/info.yml

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

c41a4ac7-ee18-42b6-b5ab-8942cb2bf3dc

Propose edits, view related rules, and engage with the community through comments.

Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

[[ reason ]]

What does this mean?

Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

[[ reason ]]

What do these messages mean?

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

[[ currentRule.title ]]

Community Discussion