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Threat Hunting

Mar 31, 2024, 5 min read

Threat Hunting

APT:

DragonFly as defined by MITRE “Dragonfly is a cyber espionage group that has been attributed to Russia’s Federal Security Service (FSB) Center 16. Active since at least 2010, Dragonfly has targeted defense and aviation companies, government entities, companies related to industrial control systems, and critical infrastructure sectors worldwide through supply chain, spearphishing, and drive-by compromise attacks”

TTPs:

  • Schedule Tasks Creation
  • Brute Force Attack
  • Phishing Email

Detection and Prevention:

Schedule Task Creation:

Installing Sysmon:

Windows:

  1. Download Sysmon at this link: https://docs.microsoft.com/en-us/sysinternals/downloads/sysmon
  2. Download the sysmon XML config file: https://wazuh.com/resources/blog/emulation-of-attack-techniques-and-detection-with-wazuh/sysmonconfig.xml
  3. Now in the downloads folder run in an admin Powershell prompt
.\Sysmon.exe -accepteula -i .\sysmonconfig.xml

Contents of the XML:

- <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
- <System>
  <Provider Name="Microsoft-Windows-Sysmon" Guid="{5770385f-c22a-43e0-bf4c-06f5698ffbd9}" /> 
  <EventID>12</EventID> 
  <Version>2</Version> 
  <Level>4</Level> 
  <Task>12</Task> 
  <Opcode>0</Opcode> 
  <Keywords>0x8000000000000000</Keywords> 
  <TimeCreated SystemTime="2022-04-13T11:59:41.5535365Z" /> 
  <EventRecordID>184</EventRecordID> 
  <Correlation /> 
  <Execution ProcessID="5944" ThreadID="4436" /> 
  <Channel>Microsoft-Windows-Sysmon/Operational</Channel> 
  <Computer>DESKTOP-4E0BQFT</Computer> 
  <Security UserID="S-1-5-18" /> 
  </System>
- <EventData>
  <Data Name="RuleName">technique_id=T1053,technique_name=Scheduled Task</Data> 
  <Data Name="EventType">CreateKey</Data> 
  <Data Name="UtcTime">2022-04-13 11:59:41.545</Data> 
  <Data Name="ProcessGuid">{76e50f37-2fc0-6244-1300-000000000300}</Data> 
  <Data Name="ProcessId">364</Data> 
  <Data Name="Image">C:\Windows\system32\svchost.exe</Data> 
  <Data Name="TargetObject">HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tree\test-task</Data> 
  <Data Name="User">NT AUTHORITY\SYSTEM</Data> 
  </EventData>
  </Event>

Wazuh Server config for Sysmon:

  1. In the /var/ossec/etc/shared/default/agent.conf Add the lines below
<agent_config os="windows">
  <localfile>
    <location>Microsoft-Windows-Sysmon/Operational</location>
    <log_format>eventchannel</log_format>
  </localfile>
</agent_config>
  1. Next we must add the rule to the /var/ossec/etc/rules/local_rules.xml
<group name="windows,sysmon,">
  <rule id="115006" level="6">
    <if_group>windows</if_group>
    <field name="win.eventdata.ruleName" type="pcre2">^technique_id=T1053,technique_name=Scheduled Task$</field>
    <field name="win.eventdata.eventType" type="pcre2">^CreateKey$</field>
    <description>A Newly Scheduled Task has been Detected on $(win.system.computer)</description>
    <mitre>
        <id>T1053</id>
    </mitre>
  </rule>
 
  <rule id="115007" level="0">
    <if_sid>115006</if_sid>
    <field name="win.eventdata.targetObject" type="pcre2">^HKLM\\\\SOFTWARE\\\\Microsoft\\\\Windows NT\\\\CurrentVersion\\\\Schedule\\\\TaskCache\\\\Tree\\\\Microsoft\\\\Windows\\\\UpdateOrchestrator$</field>
    <description>Suppression rule for scheduled task created by update orchestrator</description>
  </rule>
</group>

Creating an Active Response Script:

  1. Create the file C:\Program Files (x86)\ossec-agent\active-response\bin\analyze-scheduled-task.cmd and add the code below.
@echo off
 
setlocal enableDelayedExpansion
 
reg Query "HKLM\Hardware\Description\System\CentralProcessor\0" | find /i "x86" > NUL && SET OS=64BIT
 
if %OS%==64BIT (
    SET logFile="%programfiles(x86)%\ossec-agent\logs\scheduled-tasks.log"
)
 
set input=
for /f "delims=" a
)
 
powershell -command "$string = '%input%'; $match = select-string 'HKLM\\\\SOFTWARE\\\\Microsoft\\\\Windows NT\\\\CurrentVersion\\\\Schedule\\\\TaskCache\\\\Tree.*\\\\(\S*)\\r\\n' -inputobject $string; $taskName = $match.Matches.groups[1].value; $task = Get-ScheduledTask | where TaskName -EQ $taskName; $jsonTask = $task.Actions | ConvertTo-Json -Compress; try{$stream = [System.IO.StreamWriter]::new( '%logFile%', $true );'{\"ScheduledTaskAR\": ' + $jsonTask + ', \"TaskName\": \"' + $taskName + '\"}' | ForEach-Object{ $stream.WriteLine( $_ ) }}finally{$stream.close()}; exit"

Configure Wazuh Agent to Monitor Response Log:

  1. In the wazuh manager webui go to groups.

  2. Edit the windows group

  3. Add the lines below

<localfile>
    <location>logs\scheduled-tasks.log</location>
    <log_format>syslog</log_format>
</localfile>

If you don’t have a windows group can add the lines below to /var/ossec/etc/shared/default/agent.conf on the wazuh server.

<agent_config os="windows">
  <localfile>
    <location>logs\scheduled-tasks.log</location>
    <log_format>syslog</log_format>
  </localfile>
</agent_config>

Now test to see if the scheduled-tasks.log is created

Run the command below to create a test task

schtasks /create /tn test-task /tr "C:\Windows\System32\calc.exe" /sc onlogon /ru System /f

Now the file C:\Program Files (x86)\ossec-agent\logs\scheduled-tasks.log should be created. It will look something like:

{
  "ScheduledTaskAR": {
    "CimClass": {
      "CimSuperClassName": "MSFT_TaskAction",
      "CimSuperClass": {
        "CimSuperClassName": null,
        "CimSuperClass": null,
        "CimClassProperties": "Id",
        "CimClassQualifiers": "",
        "CimClassMethods": "",
        "CimSystemProperties": "Microsoft.Management.Infrastructure.CimSystemProperties"
      },
      "CimClassProperties": [
        "Id",
        "Arguments",
        "Execute",
        "WorkingDirectory"
      ],
      "CimClassQualifiers": [],
      "CimClassMethods": [],
      "CimSystemProperties": {
        "Namespace": "Root/Microsoft/Windows/TaskScheduler",
        "ServerName": "DESKTOP-4E0BQFT",
        "ClassName": "MSFT_TaskExecAction",
        "Path": null
      }
    },
    "CimInstanceProperties": [
      {
        "Name": "Id",
        "Value": null,
        "CimType": 14,
        "Flags": "Property, NotModified, NullValue",
        "IsValueModified": false
      },
      {
        "Name": "Arguments",
        "Value": null,
        "CimType": 14,
        "Flags": "Property, NotModified, NullValue",
        "IsValueModified": false
      },
      {
        "Name": "Execute",
        "Value": "C:\\Windows\\System32\\calc.exe",
        "CimType": 14,
        "Flags": "Property, NotModified",
        "IsValueModified": false
      },
      {
        "Name": "WorkingDirectory",
        "Value": null,
        "CimType": 14,
        "Flags": "Property, NotModified, NullValue",
        "IsValueModified": false
      }
    ],
    "CimSystemProperties": {
      "Namespace": "Root/Microsoft/Windows/TaskScheduler",
      "ServerName": "DESKTOP-4E0BQFT",
      "ClassName": "MSFT_TaskExecAction",
      "Path": null
    },
    "Id": null,
    "Arguments": null,
    "Execute": "C:\\Windows\\System32\\calc.exe",
    "WorkingDirectory": null,
    "PSComputerName": null
  },
  "TaskName": "test-task"
}o

Now delete the task

schtasks /delete /tn test-task

Creating the Rule:

On the Wazuh server add the lines below into /var/ossec/etc/rules/local_rules.xml inside the <group name=“windows,sysmon,“>

<rule id="115008" level="10">
    <decoded_as>json</decoded_as>
    <field name="ScheduledTaskAR.Arguments" type="pcre2" negate="yes">^null$</field>
    <field name="TaskName" type="pcre2">(.|\s)*\S(.|\s)*</field>
    <description>A new scheduled task "$(TaskName)" has been created on "$(ScheduledTaskAR.CimSystemProperties.ServerName)". The task will execute the command - "$(ScheduledTaskAR.Execute) $(ScheduledTaskAR.Arguments)".</description>
    <mitre>
        <id>T1053</id>
    </mitre>
</rule>
  
  <rule id="115009" level="10">
    <decoded_as>json</decoded_as>
    <field name="ScheduledTaskAR.Arguments" type="pcre2">^null$</field>
    <field name="TaskName" type="pcre2">(.|\s)*\S(.|\s)*</field>
    <description>A new scheduled task "$(TaskName)" has been created on "$(ScheduledTaskAR.CimSystemProperties.ServerName)". The task will execute the command - "$(ScheduledTaskAR.Execute)".</description>
    <mitre>
        <id>T1053</id>
    </mitre>
</rule>

Now restart wazuh manager on the wazuh server

systemctl restart wazuh-manager

Finished Product

In the webui it should show up as below:

Brute Force Attacks:

Wazuh Server setup:

  1. In the /var/ossec/etc/ossec.conf file make sure the lines below are not commented
<command>
  <name>firewall-drop</name>
  <executable>firewall-drop</executable>
  <timeout_allowed>yes</timeout_allowed>
</command>
  1. Now in the same file add the lines. There is a section towards the middle of the file that has <active-response> commented out and you can add this right below that.
 <active-response>
    <command>firewall-drop</command>
    <location>local</location>
    <rules_id>5763</rules_id>
    <timeout>180</timeout>
  </active-response>
  1. Now restart the Wazuh manager service:
sudo systemctl restart wazuh-manager

Testing:

  1. Run commands below to install hydra and trigger active response.
sudo apt update && sudo apt install -y hydra
  1. Now hydra usage:
sudo hydra 4 -l <RHEL_USERNAME> -P <PASSWD_LIST.txt> <RHEL_IP> ssh

Final Output:

Phishing Emails:

The file below is a document I made as a proof of concept for a set of instructions that could be given out to a corporation.

Phishing Email Prevention - Phishing Email Prevention.pdf

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