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Detection rules › Kusto

NGINX - Command in URI

Status
available
Severity
high
Time window
10m
Source
github.com/Azure/Azure-Sentinel

'Detects command in URI'

MITRE ATT&CK coverage

TacticTechniques
Initial AccessT1133 External Remote Services, T1190 Exploit Public-Facing Application

Rule body kusto

id: d84739ce-2f46-4391-b25e-a2edbea19d7e
name: NGINX - Command in URI
description: |
  'Detects command in URI'
severity: High
status: Available
requiredDataConnectors:
  - connectorId: CustomLogsAma
    dataTypes:
      - NGINX_CL
queryFrequency: 10m
queryPeriod: 10m
triggerOperator: gt
triggerThreshold: 0
tactics:
  - InitialAccess
relevantTechniques:
  - T1190
  - T1133
query: |
  let cmd_list = dynamic(['cat%20/etc/passwd', '/etc/passwd', 'ping -i', '/usr/bin/id(', '%2f%75%73%72%2f%62%69%6e%2f%69%64', 'phpinfo()', '%70%68%70%69%6e%66%6f%28%29', ';id', '%3b%69%64', '/bin/bash -c', '%2f%62%69%6e%2f%62%61%73%68%20%2d%63%27', '/bin/bash', '%2f%62%69%6e%2f%62%61%73%68', 'sleep(', '%73%6c%65%65%70%28', 'curl', '%63%75%72%6c', '&dir', '%26%64%69%72', '& dir', '%26%20%64%69%72', '<script>', '%3c%73%63%72%69%70%74%3e', 'eval(', '%65%76%61%6c%28', 'exec(', '%65%78%65%63%28', 'whoami', '%77%68%6f%61%6d%69', 'wget', 'python', 'gcc', 'uname', 'systeminfo', '%77%67%65%74', '%70%79%74%68%6f%6e', '%75%6e%61%6d%65', '%73%79%73%74%65%6d%69%6e%66%6f']);
  NGINXHTTPServer
  | where UrlOriginal has_any (cmd_list)
  | extend UrlCustomEntity = UrlOriginal
entityMappings:
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: UrlCustomEntity
version: 1.0.3
kind: Scheduled

Stages and Predicates

Let binding: cmd_list

let cmd_list = dynamic(['cat%20/etc/passwd', '/etc/passwd', 'ping -i', '/usr/bin/id(', '%2f%75%73%72%2f%62%69%6e%2f%69%64', 'phpinfo()', '%70%68%70%69%6e%66%6f%28%29', ';id', '%3b%69%64', '/bin/bash -c', '%2f%62%69%6e%2f%62%61%73%68%20%2d%63%27', '/bin/bash', '%2f%62%69%6e%2f%62%61%73%68', 'sleep(', '%73%6c%65%65%70%28', 'curl', '%63%75%72%6c', '&dir', '%26%64%69%72', '& dir', '%26%20%64%69%72', '<script>', '%3c%73%63%72%69%70%74%3e', 'eval(', '%65%76%61%6c%28', 'exec(', '%65%78%65%63%28', 'whoami', '%77%68%6f%61%6d%69', 'wget', 'python', 'gcc', 'uname', 'systeminfo', '%77%67%65%74', '%70%79%74%68%6f%6e', '%75%6e%61%6d%65', '%73%79%73%74%65%6d%69%6e%66%6f']);

Stage 1: source

NGINXHTTPServer

Stage 2: where

| where UrlOriginal has_any (cmd_list)

References cmd_list (defined above).

Stage 3: extend

| extend UrlCustomEntity = UrlOriginal

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.

FieldKindValues
UrlOriginalmatch
  • %26%20%64%69%72
  • %26%64%69%72
  • %2f%62%69%6e%2f%62%61%73%68
  • %2f%62%69%6e%2f%62%61%73%68%20%2d%63%27
  • %2f%75%73%72%2f%62%69%6e%2f%69%64
  • %3b%69%64
  • %3c%73%63%72%69%70%74%3e
  • %63%75%72%6c
  • %65%76%61%6c%28
  • %65%78%65%63%28
  • %70%68%70%69%6e%66%6f%28%29
  • %70%79%74%68%6f%6e
  • %73%6c%65%65%70%28
  • %73%79%73%74%65%6d%69%6e%66%6f
  • %75%6e%61%6d%65
  • %77%67%65%74
  • %77%68%6f%61%6d%69
  • & dir
  • &dir
  • /bin/bash
  • /bin/bash -c
  • /etc/passwd
  • /usr/bin/id(
  • ;id
  • <script>
  • cat%20/etc/passwd
  • curl
  • eval(
  • exec(
  • gcc
  • phpinfo()
  • ping -i
  • python
  • sleep(
  • systeminfo
  • uname
  • wget
  • whoami

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

FieldSource
UrlCustomEntityextend