CmdID / Rules / Linux

UNC4841 - Download Tar File From Untrusted Direct IP Via Wget

A Sigma rule for process creation on Linux, from SigmaHQ’s emerging threats rules, by Nasreddine Bencherchali (Nextron Systems).

high 1 ATT&CK technique 1 program it names

What it looks for

its detection, as SigmaHQ writes it

detection:
  filter_main_local_ips:
    CommandLine|contains:
      - 'https://10.'
      - 'https://192.168.'
      - 'https://172.16.'
      - 'https://172.17.'
      - 'https://172.18.'
      - 'https://172.19.'
      - 'https://172.20.'
      - 'https://172.21.'
      - 'https://172.22.'
      - 'https://172.23.'
      - 'https://172.24.'
      - 'https://172.25.'
      - 'https://172.26.'
      - 'https://172.27.'
      - 'https://172.28.'
      - 'https://172.29.'
      - 'https://172.30.'
      - 'https://172.31.'
      - 'https://127.'
      - 'https://169.254.'
  selection:
    CommandLine|contains: '--no-check-certificate'
    CommandLine|endswith: '.tar'
    CommandLine|re: 'https://[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'
    Image|endswith: '/wget'
  condition: selection and not 1 of filter_main_*

The rule’s detection, its selections and fields in order of name. The whole rule, with its references and false positives, is on SigmaHQ, by Nasreddine Bencherchali (Nextron Systems), under the Detection Rule License 1.1. CmdID evaluates it on a command line alone: a test on what a command line cannot show, such as the parent process or the user, is not met.

None of the everyday examples and documented commands on CmdID’s program pages trips it. To see whether a command line does, paste it into CmdID.

Programs and files it names

their pages here

wget

ATT&CK

the techniques it is tagged with

T1140Deobfuscate/Decode Files or Information

UNC4841 - Download Tar File From Untrusted Direct IP Via Wget

What it looks for

Programs and files it names

ATT&CK

Other rules for T1140 Deobfuscate/Decode Files or Information