Whids – Open Source Endpoint Detection System for Windows

October 25, 2019 Comments Off

This is an hybrid solution combining a flexible Host IDS with detection based Incident Response capabilities. The detection engine is built on top of a previously developped rule engine Gene specially designed to match Windows events against user defined rules.

Why

Provide an Open Source EDR like tool
Flexible detection
Easy integration with other open-source tools (MISP, The Hive …)

How

Detection

On host real time detection
Listens to Windows event log channels and apply detection rules
User defined rules (we know why we detect something)
Designed to be used with MS Sysmon
Enriches Windows events in order to build powerfull detection primitives
Central agent to distributes rules and collect alerts

Incident Response

Reacts on detection (when an event above a given criticality is detected, artifacts are collected)
Real time evidence collection (files, process memory and registries)
Central agent to collect evidences

Demo

Rule Example

Here is an example of a rule designed to catch suspicious access to lsass.exe as it is done by the well known Mimikatz credential dump tool.

{
  "Name": "MaliciousLsassAccess",
  "Tags": ["Mimikatz", "Credentials", "Lsass"],
  "Meta": {
    "EventIDs": [10],
    "Channels": ["Microsoft-Windows-Sysmon/Operational"],
    "Computers": [],
    "Traces": [],
    "Criticality": 10,
    "Author": "0xrawsec"
  },
  "Matches": [
    "$ct: CallTrace ~= 'UNKNOWN'",
    "$lsass: TargetImage ~= '(?i:\\\\lsass\\.exe$)'"
  ],
  "Condition": "$lsass and $ct"
}

You can find a bunch of other rules as well as a quick introduction to the syntax of the rules on the Gene repository.

In Action

Running WHIDS with an already running Powershell Empire agent which invokes Mimikatz module.

Herafter is the kind of output returned by WHIDS. An additional section is added to the JSON event where the criticality of the alert is reported along with the different signatures which matched the event.

{
  "Event": {
    "EventData": {
      "CallTrace": "C:\\Windows\\SYSTEM32\\ntdll.dll+4bf9a|C:\\Windows\\system32\\KERNELBASE.dll+189b7|UNKNOWN(00000000259123BC)",
      "GrantedAccess": "0x1410",
      "SourceImage": "C:\\Windows\\system32\\WindowsPowerShell\\v1.0\\powershell.exe",
      "SourceProcessGUID": "{49F1AF32-DD18-5A72-0000-0010042C0A00}",
      "SourceProcessId": "2248",
      "SourceThreadId": "3308",
      "TargetImage": "C:\\Windows\\system32\\lsass.exe",
      "TargetProcessGUID": "{49F1AF32-DB3B-5A72-0000-001013690000}",
      "TargetProcessId": "492",
      "UtcTime": "2018-02-01 11:24:53.331"
    },
    "GeneInfo": {
      "Criticality": 10,
      "Signature": [
        "MaliciousLsassAccess"
      ]
    },
    "System": {
        "Classical Windows Event System Section": "..."
    }
  }
}

Installation

WHIDS

Download and extract the latest WHIDS release https://github.com/0xrawsec/whids/releases
If you want WHIDS to run along with Sysmon (strongly recommended), install it first. An optimal configuration file is shipped with the release so that you can take the most out of WHIDS. At installation the Sysmon service will be made dependant of WHIDS service so that we are sure the IDS runs before Sysmon starts generating some events.
Run manage.bat as administrator
Launch installation by selecting the appropriate option
Verify that files have been created at the installation directory
With a text editor opened as administrator (to prevent changing the rights of the WHIDS installation directory) open config.json and modify it as you wish. This can also be done from manage.bat
Skip this if running with a connection to a manager, because rules will be updated automatically. If there is nothing in the rules directory the tool will be useless, so make sure there are some gene rules in there. Some rules are packaged with WHIDS and you will be prompted if you want to install those or not. If you want the last up to date rules, you can get those here (take the compiled ones)
Start the services from appropriate option in manage.bat or just reboot (preferred option otherwise some enrichment fields will be incomplete leading to false alerts)
If you configured a manager do not forget to run it in order to receive alerts and dumps

NB: whenever you go to the installation directory with Explorer.exe and if you are Administrator the explorer will ask you if you want to change the permission of the directory. DO NOT CLICK YES, otherwise it will break the folder permissions put in place at installation time. Always access installation directory from applications started as Administrator (i.e. text editor).

Configuration

WHIDS

WHIDS configuration file example

{
    // Path to the rules directory used for detection
    "rules-db": "C:\\Program Files\\Whids\\Database\\Rules",
    // Path to the containers used in some of the rules
    // containers must be GZIP compressed and have .cont.gz extension
    // basename without extension is taken as container name
    // Example: blacklist.cont.gz will create blacklist container
    "containers-db": "C:\\Program Files\\Whids\\Database\\Containers",
    // Forwarder related configuration
    "forwarder": {
        "manager-client": {
            // Hostname or IP address of remote manager
            "host": "",
            // Port used by remote manager
            "port": 0,
            // Protocol used http or https
            "proto": "",
            // Key used to authenticate the client
            "key": "",
            // Server key used to authenticate remote server
            "server-key": "",
            // Whether or not the TLS certificate should be verified
            "unsafe": false,
            // Maximum upload side for dump forwarding
            "max-upload-size": 104857600
        },
        // Alert logging settings
        "logging": {
            // Path where to store the alerts
            "dir": "C:\\Program Files\\Whids\\Logs\\Alerts",
            // Rotation interval
            "rotation-interval": "24h"
        },
        // If local=true the forwarder won't communicate with manager
        "local": true
    },
    // Windows event log channels to monitor
    // run "whids -h" to get the list of aliases
    // otherwise any Windows channel can be used here 
    "channels": [
        "all"
    ],
    // Dump related settings
    "dump": {
        // Dump mode: file, memory or all (can be empty)
        // file: dumps anything identified as a file in the event
        // memory: dumps (guilty) process memory in Windows minidump format
        // registry: dumps registry in case alert concerns a registry
        "mode": "file|registry",
        // Dumps when criticality of the events is above or equal to treshold
        "treshold": 8,
        // Where to store dumps
        "dir": "C:\\Program Files\\Whids\\Dumps",
        // Whether or not to enable dump compression
        "compression": true
    },
    // Log events with criticality above or equal to treshold
    "criticality-treshold": 5,
    // Sleep time in seconds between two rules updates (negative number means no update)
    "update-interval": 60,
    // Whether on not hooks should be enabled
    "en-hooks": true,
    // Logfile used to store WHIDS stderr
    "logfile": "C:\\Program Files\\Whids\\Logs\\whids.log",
    // Log all the events passing through the engine (usefull for event dumping or debugging)
    "log-all": false,
    // Tells WHIDS that it is running on an endpoint. If false any kind 
    // of dump is disabled to avoid dump things if installed on a WEC
    "endpoint": true
}

Manager

Manager configuration example

{
    // Hostname / IP on which to run the manager
    "host": "192.168.56.1",
    // Port used by the manager
    "port": 1519,
    // Logfile (automatically rotated) where to store alerts received
    "logfile": "alerts.log",
    // Server authentication key (see server-key in WHIDS config)
    "key": "someserverkey",
    // List of authorized client keys (see key in WHIDS config)
    // If the client is not authorized in this list, all the connections 
    // to the manager will abort
    "authorized": [
      "clientapikey"
    ],
    // TLS settings
    "tls": {
        // Server certificate to use
        "cert": "cert.pem",
        // Server key to use
        "key": "key.pem"
    },
    "misp": {
        // Protocol to use for MISP connection
        "protocol" :"https",
        // MISP host
        "host" : "misp.host",
        // API key to use
        "api-key" :"your misp api key"
    },
    // Rules directory used to serve rules to the clients
    "rules-dir": "",
    // Rules of containers used in rules (served to the clients)
    // a container name is the basename of the file without extension
    // Example: /some/container/dir/blacklist.txt will take the content
    // of the file and use it as being a Gene container named blacklist
    "containers-dir": ""
    // Directory used to store dumps sent by the client
    "dump-dir": "",
}