Download from Suspicious Dyndns Hosts

Status: test
Severity: medium
Log source: category proxy
Author: Florian Roth (Nextron Systems)
Source: github.com/SigmaHQ/sigma

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

MITRE ATT&CK coverage

Tactic	Techniques
Command & Control	`T1105` Ingress Tool Transfer, `T1568` Dynamic Resolution

Rule body 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

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    c-uri-extension:
        - 'exe'
        - 'vbs'
        - 'bat'
        - 'rar'
        - 'ps1'
        - 'doc'
        - 'docm'
        - 'xls'
        - 'xlsm'
        - 'pptm'
        - 'rtf'
        - 'hta'
        - 'dll'
        - 'ws'
        - 'wsf'
        - 'sct'
        - 'zip'
    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'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`c-uri-extension`	eq	`bat` `dll` `doc` `docm` `exe` `hta` `pptm` `ps1` `rar` `rtf` `sct` `vbs` `ws` `wsf` `xls` `xlsm` `zip`
`cs-host`	ends_with	`.25u.com` `.adultdns.net` `.craftx.biz` `.ddns.info` `.ddns.name` `.ddns01.com` `.dlinkddns.com` `.dns-dns.com` `.dns53.biz` `.dnsapi.info` `.dnsd.info` `.dnsdynamic.com` `.dnsdynamic.net` `.dnsget.org` `.dnsomatic.com` `.dyndns-at-home.com` `.dyndns.info` `.dyndns.org` `.dyndns.tv` `.fe100.net` `.flashserv.net` `.ftp21.net` `.hopto.org` `.http01.com` `.http80.info` `.https443.com` `.ignorelist.com` `.imap01.com` `.jkub.com` `.jumpingcrab.com` `.kadm5.com` `.mooo.com` `.myftp.biz` `.myftp.org` `.mysq1.net` `.myvnc.com` `.no-ip.biz` `.no-ip.com` `.no-ip.info` `.no-ip.org` `.noip.com` `.ns360.info` `.ntdll.net` `.ole32.com` `.proxy8080.com` `.servebeer.com` `.serveblog.net` `.serveftp.com` `.servegame.com` `.servehalflife.com` `.servehttp.com` `.servemp3.com` `.servepics.com` `.servequake.com` `.slyip.net` `.sql01.com` `.ssh01.com` `.ssh22.net` `.strangled.net` `.tempors.com` `.tftpd.net` `.ttl60.com` `.ttl60.org` `.user32.com` `.voip01.com` `.webhop.net` `.wow64.net` `.x64.me` `.xns01.com` `.zapto.org`

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

Download from Suspicious Dyndns Hosts

MITRE ATT&CK coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection`

Indicators

Keyboard shortcuts

Search operators

Download from Suspicious Dyndns Hosts

MITRE ATT&CK coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection

Indicators

Stage 0: `condition`

Stage 1: `selection`