WebDav Put Request

Status: test
Severity: low
Log source: product zeek, service http
Author: Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research)
Source: github.com/SigmaHQ/sigma

A General detection for WebDav user-agent being used to PUT files on a WebDav network share. This could be an indicator of exfiltration.

MITRE ATT&CK coverage

Tactic	Techniques
Exfiltration	`T1048.003` Exfiltration Over Alternative Protocol: Exfiltration Over Unencrypted Non-C2 Protocol

Rule body

title: WebDav Put Request
id: 705072a5-bb6f-4ced-95b6-ecfa6602090b
status: test
description: A General detection for WebDav user-agent being used to PUT files on a WebDav network share. This could be an indicator of exfiltration.
references:
    - https://github.com/OTRF/detection-hackathon-apt29/issues/17
author: Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research)
date: 2020-05-02
modified: 2024-03-13
tags:
    - attack.exfiltration
    - attack.t1048.003
logsource:
    product: zeek
    service: http
detection:
    selection:
        user_agent|contains: 'WebDAV'
        method: 'PUT'
    filter:
        id.resp_h|cidr:
            - '10.0.0.0/8'
            - '127.0.0.0/8'
            - '172.16.0.0/12'
            - '192.168.0.0/16'
            - '169.254.0.0/16'
    condition: selection and not filter
falsepositives:
    - Unknown
level: low

Stages and Predicates

Stage 0: `condition`

selection and not filter

Stage 1: `selection`

selection:
    user_agent|contains: 'WebDAV'
    method: 'PUT'

Stage 2: `not filter`

filter:
    id.resp_h|cidr:
        - '10.0.0.0/8'
        - '127.0.0.0/8'
        - '172.16.0.0/12'
        - '192.168.0.0/16'
        - '169.254.0.0/16'

Exclusions

The rule actively suppresses these predicates.

Field	Kind	Excluded values	Search
`id.resp_h`	cidr_match	`10.0.0.0/8`	`excludes:id.resp_h` `field:"id.resp_h" value:"10.0.0.0/8"`
`id.resp_h`	cidr_match	`127.0.0.0/8`	`excludes:id.resp_h` `field:"id.resp_h" value:"127.0.0.0/8"`
`id.resp_h`	cidr_match	`169.254.0.0/16`	`excludes:id.resp_h` `field:"id.resp_h" value:"169.254.0.0/16"`
`id.resp_h`	cidr_match	`172.16.0.0/12`	`excludes:id.resp_h` `field:"id.resp_h" value:"172.16.0.0/12"`
`id.resp_h`	cidr_match	`192.168.0.0/16`	`excludes:id.resp_h` `field:"id.resp_h" value:"192.168.0.0/16"`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`method`	eq	`PUT`	`field:"method" kind:eq value:"PUT"`
`user_agent`	match	`WebDAV`	`field:"aws::userAgent" kind:match value:"WebDAV"`