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Detection rules › Sigma

DNS RCE CVE-2020-1350

Status
test
Severity
critical
Log source
product windows, category process_creation
Author
Florian Roth (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects exploitation of DNS RCE bug reported in CVE-2020-1350 by the detection of suspicious sub process

MITRE ATT&CK coverage

TacticTechniques
Initial AccessT1190 Exploit Public-Facing Application
ExecutionT1569.002 System Services: Service Execution

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation
Security-AuditingEvent ID 4688A new process has been created.

Rule body yaml

title: DNS RCE CVE-2020-1350
id: b5281f31-f9cc-4d0d-95d0-45b91c45b487
status: test
description: Detects exploitation of DNS RCE bug reported in CVE-2020-1350 by the detection of suspicious sub process
references:
    - https://research.checkpoint.com/2020/resolving-your-way-into-domain-admin-exploiting-a-17-year-old-bug-in-windows-dns-servers/
    - https://web.archive.org/web/20230329172447/https://blog.menasec.net/2019/02/threat-hunting-24-microsoft-windows-dns.html
author: Florian Roth (Nextron Systems)
date: 2020-07-15
modified: 2022-07-12
tags:
    - attack.initial-access
    - attack.t1190
    - attack.execution
    - attack.t1569.002
    - cve.2020-1350
    - detection.emerging-threats
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: '\System32\dns.exe'
    filter:
        Image|endswith:
            - '\System32\werfault.exe'
            - '\System32\conhost.exe'
            - '\System32\dnscmd.exe'
            - '\System32\dns.exe'
    condition: selection and not filter
falsepositives:
    - Unknown but benign sub processes of the Windows DNS service dns.exe
level: critical

Stages and Predicates

Stage 0: condition

selection and not filter

Stage 1: selection

selection:
    ParentImage|endswith: '\System32\dns.exe'

Stage 2: not filter

filter:
    Image|endswith:
        - '\System32\werfault.exe'
        - '\System32\conhost.exe'
        - '\System32\dnscmd.exe'
        - '\System32\dns.exe'

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

FieldKindExcluded values
Imageends_with\System32\conhost.exe
Imageends_with\System32\dns.exe
Imageends_with\System32\dnscmd.exe
Imageends_with\System32\werfault.exe

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
ParentImageends_with
  • \System32\dns.exe