Sigma detection rules

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Sigma

3 rules indexed · SIEM-agnostic detection content

Sigma is the open generic signature format for SIEM systems. Each rule below converts to native syntax for Splunk, Elastic, Sentinel, and other SIEMs. Expand any rule to see its raw YAML.

Severity critical high medium low all severities

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Detection rules

3 shown of 3

high

Communication To Ngrok Tunneling Service - Linux

Detects an executable accessing an ngrok tunneling endpoint, which could be a sign of forbidden exfiltration of data exfiltration by malicious actors

status test author Florian Roth (Nextron Systems) id 19bf6fdb-7721-4f3d-867f-53467f6a5db6

view Sigma YAML

title: Communication To Ngrok Tunneling Service - Linux
id: 19bf6fdb-7721-4f3d-867f-53467f6a5db6
status: test
description: Detects an executable accessing an ngrok tunneling endpoint, which could be a sign of forbidden exfiltration of data exfiltration by malicious actors
references:
    - https://twitter.com/hakluke/status/1587733971814977537/photo/1
    - https://ngrok.com/docs/secure-tunnels/tunnels/ssh-reverse-tunnel-agent
author: Florian Roth (Nextron Systems)
date: 2022-11-03
tags:
    - attack.exfiltration
    - attack.command-and-control
    - attack.t1567
    - attack.t1568.002
    - attack.t1572
    - attack.t1090
    - attack.t1102
    - attack.s0508
logsource:
    product: linux
    category: network_connection
detection:
    selection:
        DestinationHostname|contains:
            - 'tunnel.us.ngrok.com'
            - 'tunnel.eu.ngrok.com'
            - 'tunnel.ap.ngrok.com'
            - 'tunnel.au.ngrok.com'
            - 'tunnel.sa.ngrok.com'
            - 'tunnel.jp.ngrok.com'
            - 'tunnel.in.ngrok.com'
    condition: selection
falsepositives:
    - Legitimate use of ngrok
level: high

high

Communication To Ngrok Tunneling Service Initiated

Detects an executable initiating a network connection to "ngrok" tunneling domains. Attackers were seen using this "ngrok" in order to store their second stage payloads and malware. While communication with such domains can be legitimate, often times is a sign of either data exfiltration by malicious actors or additional download.

status test author Florian Roth (Nextron Systems) id 1d08ac94-400d-4469-a82f-daee9a908849

view Sigma YAML

title: Communication To Ngrok Tunneling Service Initiated
id: 1d08ac94-400d-4469-a82f-daee9a908849
related:
    - id: 18249279-932f-45e2-b37a-8925f2597670
      type: similar
status: test
description: |
    Detects an executable initiating a network connection to "ngrok" tunneling domains.
    Attackers were seen using this "ngrok" in order to store their second stage payloads and malware.
    While communication with such domains can be legitimate, often times is a sign of either data exfiltration by malicious actors or additional download.
references:
    - https://twitter.com/hakluke/status/1587733971814977537/photo/1
    - https://ngrok.com/docs/secure-tunnels/tunnels/ssh-reverse-tunnel-agent
author: Florian Roth (Nextron Systems)
date: 2022-11-03
modified: 2024-02-02
tags:
    - attack.exfiltration
    - attack.command-and-control
    - attack.t1567
    - attack.t1568.002
    - attack.t1572
    - attack.t1090
    - attack.t1102
    - attack.s0508
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        DestinationHostname|contains:
            - 'tunnel.us.ngrok.com'
            - 'tunnel.eu.ngrok.com'
            - 'tunnel.ap.ngrok.com'
            - 'tunnel.au.ngrok.com'
            - 'tunnel.sa.ngrok.com'
            - 'tunnel.jp.ngrok.com'
            - 'tunnel.in.ngrok.com'
    condition: selection
falsepositives:
    - Legitimate use of the ngrok service.
level: high

medium

Download from Suspicious Dyndns Hosts

Detects download of certain file types from hosts with dynamic DNS names (selected list)

status test author Florian Roth (Nextron Systems) id 195c1119-ef07-4909-bb12-e66f5e07bf3c

view Sigma YAML

title: Download from Suspicious Dyndns Hosts
id: 195c1119-ef07-4909-bb12-e66f5e07bf3c
status: test
description: Detects download of certain file types from hosts with dynamic DNS names (selected list)
references:
    - https://www.alienvault.com/blogs/security-essentials/dynamic-dns-security-and-potential-threats
author: Florian Roth (Nextron Systems)
date: 2017-11-08
modified: 2023-05-18
tags:
    - attack.command-and-control
    - attack.t1105
    - attack.t1568
logsource:
    category: proxy
detection:
    selection:
        c-uri-extension:
            - 'exe'
            - 'vbs'
            - 'bat'
            - 'rar'
            - 'ps1'
            - 'doc'
            - 'docm'
            - 'xls'
            - 'xlsm'
            - 'pptm'
            - 'rtf'
            - 'hta'
            - 'dll'
            - 'ws'
            - 'wsf'
            - 'sct'
            - 'zip'
            # If you want to add more extensions - see https://docs.google.com/spreadsheets/d/1TWS238xacAto-fLKh1n5uTsdijWdCEsGIM0Y0Hvmc5g/
        cs-host|endswith:
            - '.hopto.org'
            - '.no-ip.org'
            - '.no-ip.info'
            - '.no-ip.biz'
            - '.no-ip.com'
            - '.noip.com'
            - '.ddns.name'
            - '.myftp.org'
            - '.myftp.biz'
            - '.serveblog.net'
            - '.servebeer.com'
            - '.servemp3.com'
            - '.serveftp.com'
            - '.servequake.com'
            - '.servehalflife.com'
            - '.servehttp.com'
            - '.servegame.com'
            - '.servepics.com'
            - '.myvnc.com'
            - '.ignorelist.com'
            - '.jkub.com'
            - '.dlinkddns.com'
            - '.jumpingcrab.com'
            - '.ddns.info'
            - '.mooo.com'
            - '.dns-dns.com'
            - '.strangled.net'
            - '.adultdns.net'
            - '.craftx.biz'
            - '.ddns01.com'
            - '.dns53.biz'
            - '.dnsapi.info'
            - '.dnsd.info'
            - '.dnsdynamic.com'
            - '.dnsdynamic.net'
            - '.dnsget.org'
            - '.fe100.net'
            - '.flashserv.net'
            - '.ftp21.net'
            - '.http01.com'
            - '.http80.info'
            - '.https443.com'
            - '.imap01.com'
            - '.kadm5.com'
            - '.mysq1.net'
            - '.ns360.info'
            - '.ntdll.net'
            - '.ole32.com'
            - '.proxy8080.com'
            - '.sql01.com'
            - '.ssh01.com'
            - '.ssh22.net'
            - '.tempors.com'
            - '.tftpd.net'
            - '.ttl60.com'
            - '.ttl60.org'
            - '.user32.com'
            - '.voip01.com'
            - '.wow64.net'
            - '.x64.me'
            - '.xns01.com'
            - '.dyndns.org'
            - '.dyndns.info'
            - '.dyndns.tv'
            - '.dyndns-at-home.com'
            - '.dnsomatic.com'
            - '.zapto.org'
            - '.webhop.net'
            - '.25u.com'
            - '.slyip.net'
    condition: selection
falsepositives:
    - Software downloads
level: medium

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