Convert indexed Sigma rules into analyst-ready detections.

title: New Connection Initiated To Potential Dead Drop Resolver Domain
id: 297ae038-edc2-4b2e-bb3e-7c5fc94dd5c7
related:
    - id: d7b09985-95a3-44be-8450-b6eadf49833e
      type: obsolete
status: test
description: |
    Detects an executable, which is not an internet browser or known application, initiating network connections to legit popular websites, which were seen to be used as dead drop resolvers in previous attacks.
    In this context attackers leverage known websites such as "facebook", "youtube", etc. In order to pass through undetected.
references:
    - https://web.archive.org/web/20220830134315/https://content.fireeye.com/apt-41/rpt-apt41/
    - https://securelist.com/the-tetrade-brazilian-banking-malware/97779/
    - https://blog.bushidotoken.net/2021/04/dead-drop-resolvers-espionage-inspired.html
    - https://github.com/kleiton0x00/RedditC2
    - https://twitter.com/kleiton0x7e/status/1600567316810551296
    - https://www.linkedin.com/posts/kleiton-kurti_github-kleiton0x00redditc2-abusing-reddit-activity-7009939662462984192-5DbI/?originalSubdomain=al
author: Sorina Ionescu, X__Junior (Nextron Systems)
date: 2022-08-17
modified: 2024-10-21
tags:
    - attack.command-and-control
    - attack.t1102
    - attack.t1102.001
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        Initiated: 'true'
        DestinationHostname|endswith:
            - '.t.me'
            - '4shared.com'
            - 'abuse.ch'
            - 'anonfiles.com'
            - 'cdn.discordapp.com'
            - 'cloudflare.com'
            - 'ddns.net'
            - 'discord.com'
            - 'docs.google.com'
            - 'drive.google.com'
            - 'dropbox.com'
            - 'dropmefiles.com'
            - 'facebook.com'
            - 'feeds.rapidfeeds.com'
            - 'fotolog.com'
            - 'ghostbin.co/'
            - 'githubusercontent.com'
            - 'gofile.io'
            - 'hastebin.com'
            - 'imgur.com'
            - 'livejournal.com'
            - 'mediafire.com'
            - 'mega.co.nz'
            - 'mega.nz'
            - 'onedrive.com'
            - 'pages.dev'
            - 'paste.ee'
            - 'pastebin.com'
            - 'pastebin.pl'
            - 'pastetext.net'
            - 'pixeldrain.com'
            - 'privatlab.com'
            - 'privatlab.net'
            - 'reddit.com'
            - 'send.exploit.in'
            - 'sendspace.com'
            - 'steamcommunity.com'
            - 'storage.googleapis.com'
            - 'technet.microsoft.com'
            - 'temp.sh'
            - 'transfer.sh'
            - 'trycloudflare.com'
            - 'twitter.com'
            - 'ufile.io'
            - 'vimeo.com'
            - 'w3spaces.com'
            - 'wetransfer.com'
            - 'workers.dev'
            - 'youtube.com'
    # Note: Add/Remove browsers/applications that you don't use or those that have custom install locations
    # Note: To avoid complex conditions the filters for some apps are generic by name only. A custom tuning is recommended for best results
    filter_main_chrome:
        Image:
            - 'C:\Program Files\Google\Chrome\Application\chrome.exe'
            - 'C:\Program Files (x86)\Google\Chrome\Application\chrome.exe'
    filter_main_chrome_appdata:
        Image|startswith: 'C:\Users\'
        Image|endswith: '\AppData\Local\Google\Chrome\Application\chrome.exe'
    filter_main_firefox:
        Image:
            - 'C:\Program Files\Mozilla Firefox\firefox.exe'
            - 'C:\Program Files (x86)\Mozilla Firefox\firefox.exe'
    filter_main_firefox_appdata:
        Image|startswith: 'C:\Users\'
        Image|endswith: '\AppData\Local\Mozilla Firefox\firefox.exe'
    filter_main_ie:
        Image:
            - 'C:\Program Files (x86)\Internet Explorer\iexplore.exe'
            - 'C:\Program Files\Internet Explorer\iexplore.exe'
    filter_main_edge_1:
        - Image|startswith: 'C:\Program Files (x86)\Microsoft\EdgeWebView\Application\'
        - Image|endswith: '\WindowsApps\MicrosoftEdge.exe'
        - Image:
              - 'C:\Program Files (x86)\Microsoft\Edge\Application\msedge.exe'
              - 'C:\Program Files\Microsoft\Edge\Application\msedge.exe'
    filter_main_edge_2:
        Image|startswith:
            - 'C:\Program Files (x86)\Microsoft\EdgeCore\'
            - 'C:\Program Files\Microsoft\EdgeCore\'
        Image|endswith:
            - '\msedge.exe'
            - '\msedgewebview2.exe'
    filter_main_safari:
        Image|contains:
            - 'C:\Program Files (x86)\Safari\'
            - 'C:\Program Files\Safari\'
        Image|endswith: '\safari.exe'
    filter_main_defender:
        Image|contains:
            - 'C:\Program Files\Windows Defender Advanced Threat Protection\'
            - 'C:\Program Files\Windows Defender\'
            - 'C:\ProgramData\Microsoft\Windows Defender\Platform\'
        Image|endswith:
            - '\MsMpEng.exe' # Microsoft Defender executable
            - '\MsSense.exe' # Windows Defender Advanced Threat Protection Service Executable
    filter_main_prtg:
        # Paessler's PRTG Network Monitor
        Image|endswith:
            - 'C:\Program Files (x86)\PRTG Network Monitor\PRTG Probe.exe'
            - 'C:\Program Files\PRTG Network Monitor\PRTG Probe.exe'
    filter_main_brave:
        Image|startswith: 'C:\Program Files\BraveSoftware\'
        Image|endswith: '\brave.exe'
    filter_main_maxthon:
        Image|contains: '\AppData\Local\Maxthon\'
        Image|endswith: '\maxthon.exe'
    filter_main_opera:
        Image|contains: '\AppData\Local\Programs\Opera\'
        Image|endswith: '\opera.exe'
    filter_main_seamonkey:
        Image|startswith:
            - 'C:\Program Files\SeaMonkey\'
            - 'C:\Program Files (x86)\SeaMonkey\'
        Image|endswith: '\seamonkey.exe'
    filter_main_vivaldi:
        Image|contains: '\AppData\Local\Vivaldi\'
        Image|endswith: '\vivaldi.exe'
    filter_main_whale:
        Image|startswith:
            - 'C:\Program Files\Naver\Naver Whale\'
            - 'C:\Program Files (x86)\Naver\Naver Whale\'
        Image|endswith: '\whale.exe'
    # Note: The TOR browser shouldn't be something you allow in your corporate network.
    # filter_main_tor:
    #     Image|contains: '\Tor Browser\'
    filter_main_whaterfox:
        Image|startswith:
            - 'C:\Program Files\Waterfox\'
            - 'C:\Program Files (x86)\Waterfox\'
        Image|endswith: '\Waterfox.exe'
    filter_main_midori:
        Image|contains: '\AppData\Local\Programs\midori-ng\'
        Image|endswith: '\Midori Next Generation.exe'
    filter_main_slimbrowser:
        Image|startswith:
            - 'C:\Program Files\SlimBrowser\'
            - 'C:\Program Files (x86)\SlimBrowser\'
        Image|endswith: '\slimbrowser.exe'
    filter_main_flock:
        Image|contains: '\AppData\Local\Flock\'
        Image|endswith: '\Flock.exe'
    filter_main_phoebe:
        Image|contains: '\AppData\Local\Phoebe\'
        Image|endswith: '\Phoebe.exe'
    filter_main_falkon:
        Image|startswith:
            - 'C:\Program Files\Falkon\'
            - 'C:\Program Files (x86)\Falkon\'
        Image|endswith: '\falkon.exe'
    filter_main_qtweb:
        Image|startswith:
            - 'C:\Program Files (x86)\QtWeb\'
            - 'C:\Program Files\QtWeb\'
        Image|endswith: '\QtWeb.exe'
    filter_main_avant:
        Image|startswith:
            - 'C:\Program Files (x86)\Avant Browser\'
            - 'C:\Program Files\Avant Browser\'
        Image|endswith: '\avant.exe'
    filter_main_whatsapp:
        Image|startswith:
            - 'C:\Program Files (x86)\WindowsApps\'
            - 'C:\Program Files\WindowsApps\'
        Image|endswith: '\WhatsApp.exe'
        DestinationHostname|endswith: 'facebook.com'
    filter_main_telegram:
        Image|contains: '\AppData\Roaming\Telegram Desktop\'
        Image|endswith: '\Telegram.exe'
        DestinationHostname|endswith: '.t.me'
    filter_main_onedrive:
        Image|contains: '\AppData\Local\Microsoft\OneDrive\'
        Image|endswith: '\OneDrive.exe'
        DestinationHostname|endswith: 'onedrive.com'
    filter_main_dropbox:
        Image|startswith:
            - 'C:\Program Files (x86)\Dropbox\Client\'
            - 'C:\Program Files\Dropbox\Client\'
        Image|endswith:
            - '\Dropbox.exe'
            - '\DropboxInstaller.exe'
        DestinationHostname|endswith: 'dropbox.com'
    filter_main_mega:
        Image|endswith:
            # Note: This is a basic/best effort filter in order to avoid FP with the MEGA installer and executable.
            #       In practice please apply exact path to avoid basic path bypass techniques.
            - '\MEGAsync.exe'
            - '\MEGAsyncSetup32_*RC.exe' # Beta versions
            - '\MEGAsyncSetup32.exe' # Installers 32bit
            - '\MEGAsyncSetup64.exe' # Installers 64bit
            - '\MEGAupdater.exe'
        DestinationHostname|endswith:
            - 'mega.co.nz'
            - 'mega.nz'
    filter_main_googledrive:
        Image|contains:
            - 'C:\Program Files\Google\Drive File Stream\'
            - 'C:\Program Files (x86)\Google\Drive File Stream\'
        Image|endswith: 'GoogleDriveFS.exe'
        DestinationHostname|endswith: 'drive.google.com'
    filter_main_discord:
        Image|contains: '\AppData\Local\Discord\'
        Image|endswith: '\Discord.exe'
        DestinationHostname|endswith:
            - 'discord.com'
            - 'cdn.discordapp.com'
    filter_main_null:
        Image: null
    filter_main_empty:
        Image: ''
    # filter_optional_qlik:
    #     Image|endswith: '\Engine.exe' # Process from qlik.com app
    condition: selection and not 1 of filter_main_*
falsepositives:
    - One might need to exclude other internet browsers found in it's network or other applications like ones mentioned above from Microsoft Defender.
    - Ninite contacting githubusercontent.com
level: high