Malware Analysis Report

2025-04-13 12:14

Sample ID 240330-dt1s5agf36
Target Client-buailt.exe
SHA256 ee1544b6bb0a35c74391f821b94208443754ac5f7e01f03bc369eac3dd70b32d
Tags
office01 quasar spyware trojan
score
10/10

Table of Contents

Analysis Overview

MITRE ATT&CK

Enterprise Matrix V15

Analysis: static1

Detonation Overview

Signatures

Analysis: behavioral1

Detonation Overview

Command Line

Signatures

Processes

Network

Files

Analysis: behavioral2

Detonation Overview

Command Line

Signatures

Processes

Network

Files

Analysis Overview

score
10/10

SHA256

ee1544b6bb0a35c74391f821b94208443754ac5f7e01f03bc369eac3dd70b32d

Threat Level: Known bad

The file Client-buailt.exe was found to be: Known bad.

Malicious Activity Summary

office01 quasar spyware trojan

Quasar family

Quasar payload

Quasar RAT

Executes dropped EXE

Drops file in System32 directory

Unsigned PE

Suspicious use of SetWindowsHookEx

Suspicious use of WriteProcessMemory

Uses Task Scheduler COM API

Creates scheduled task(s)

Suspicious use of AdjustPrivilegeToken

MITRE ATT&CK

Analysis: static1

Detonation Overview

Reported

2024-03-30 03:18

Signatures

Quasar family

quasar

Quasar payload

Description Indicator Process Target
N/A N/A N/A N/A

Unsigned PE

Description Indicator Process Target
N/A N/A N/A N/A

Analysis: behavioral1

Detonation Overview

Submitted

2024-03-30 03:18

Reported

2024-03-30 03:21

Platform

win7-20240221-en

Max time kernel

127s

Max time network

136s

Command Line

"C:\Users\Admin\AppData\Local\Temp\Client-buailt.exe"

Signatures

Quasar RAT

trojan spyware quasar

Quasar payload

Description Indicator Process Target
N/A N/A N/A N/A
N/A N/A N/A N/A
N/A N/A N/A N/A

Executes dropped EXE

Description Indicator Process Target
N/A N/A C:\Windows\system32\SubDir\Client.exe N/A

Drops file in System32 directory

Description Indicator Process Target
File created C:\Windows\system32\SubDir\Client.exe C:\Users\Admin\AppData\Local\Temp\Client-buailt.exe N/A
File opened for modification C:\Windows\system32\SubDir\Client.exe C:\Users\Admin\AppData\Local\Temp\Client-buailt.exe N/A
File opened for modification C:\Windows\system32\SubDir C:\Users\Admin\AppData\Local\Temp\Client-buailt.exe N/A
File opened for modification C:\Windows\system32\SubDir\Client.exe C:\Windows\system32\SubDir\Client.exe N/A
File opened for modification C:\Windows\system32\SubDir C:\Windows\system32\SubDir\Client.exe N/A

Creates scheduled task(s)

persistence
Description Indicator Process Target
N/A N/A C:\Windows\system32\schtasks.exe N/A
N/A N/A C:\Windows\system32\schtasks.exe N/A

Suspicious use of AdjustPrivilegeToken

Description Indicator Process Target
Token: SeDebugPrivilege N/A C:\Users\Admin\AppData\Local\Temp\Client-buailt.exe N/A
Token: SeDebugPrivilege N/A C:\Windows\system32\SubDir\Client.exe N/A

Suspicious use of SetWindowsHookEx

Description Indicator Process Target
N/A N/A C:\Windows\system32\SubDir\Client.exe N/A

Uses Task Scheduler COM API

persistence

Processes

C:\Users\Admin\AppData\Local\Temp\Client-buailt.exe

"C:\Users\Admin\AppData\Local\Temp\Client-buailt.exe"

C:\Windows\system32\schtasks.exe

"schtasks" /create /tn "Client Startup" /sc ONLOGON /tr "C:\Windows\system32\SubDir\Client.exe" /rl HIGHEST /f

C:\Windows\system32\SubDir\Client.exe

"C:\Windows\system32\SubDir\Client.exe"

C:\Windows\system32\schtasks.exe

"schtasks" /create /tn "Client Startup" /sc ONLOGON /tr "C:\Windows\system32\SubDir\Client.exe" /rl HIGHEST /f

Network

Country Destination Domain Proto
US 198.7.62.204:4782 tcp
N/A 192.168.1.1:4782 tcp
US 198.7.62.204:4782 tcp
N/A 192.168.1.1:4782 tcp
US 198.7.62.204:4782 tcp
N/A 192.168.1.1:4782 tcp

Files

memory/2156-0-0x0000000000DE0000-0x0000000001128000-memory.dmp

memory/2156-1-0x000007FEF5BE0000-0x000007FEF65CC000-memory.dmp

memory/2156-2-0x000000001B2C0000-0x000000001B340000-memory.dmp

C:\Windows\System32\SubDir\Client.exe

MD5 67058a89ce6f3786bc28af9962d6202d
SHA1 57b66752526058f244ed0802d771b0b4d70432a9
SHA256 ee1544b6bb0a35c74391f821b94208443754ac5f7e01f03bc369eac3dd70b32d
SHA512 98a0cc78d49cba94cc5edd2804697391861cd0192ce10aeb93223ad05046a1418d1380c3a3cd7a1e17f0ab290e0a10cd60d3f0e8959ca4783d2eef7460a8ce62

memory/2812-9-0x000007FEF5BE0000-0x000007FEF65CC000-memory.dmp

memory/2812-8-0x0000000001070000-0x00000000013B8000-memory.dmp

memory/2156-11-0x000007FEF5BE0000-0x000007FEF65CC000-memory.dmp

memory/2812-10-0x000000001B330000-0x000000001B3B0000-memory.dmp

memory/2812-12-0x000007FEF5BE0000-0x000007FEF65CC000-memory.dmp

memory/2812-13-0x000000001B330000-0x000000001B3B0000-memory.dmp

Analysis: behavioral2

Detonation Overview

Submitted

2024-03-30 03:18

Reported

2024-03-30 03:21

Platform

win10v2004-20240226-en

Max time kernel

145s

Max time network

153s

Command Line

"C:\Users\Admin\AppData\Local\Temp\Client-buailt.exe"

Signatures

Quasar RAT

trojan spyware quasar

Quasar payload

Description Indicator Process Target
N/A N/A N/A N/A
N/A N/A N/A N/A

Executes dropped EXE

Description Indicator Process Target
N/A N/A C:\Windows\system32\SubDir\Client.exe N/A

Drops file in System32 directory

Description Indicator Process Target
File opened for modification C:\Windows\system32\SubDir\Client.exe C:\Users\Admin\AppData\Local\Temp\Client-buailt.exe N/A
File opened for modification C:\Windows\system32\SubDir C:\Users\Admin\AppData\Local\Temp\Client-buailt.exe N/A
File opened for modification C:\Windows\system32\SubDir\Client.exe C:\Windows\system32\SubDir\Client.exe N/A
File opened for modification C:\Windows\system32\SubDir C:\Windows\system32\SubDir\Client.exe N/A
File created C:\Windows\system32\SubDir\Client.exe C:\Users\Admin\AppData\Local\Temp\Client-buailt.exe N/A

Creates scheduled task(s)

persistence
Description Indicator Process Target
N/A N/A C:\Windows\SYSTEM32\schtasks.exe N/A
N/A N/A C:\Windows\SYSTEM32\schtasks.exe N/A

Suspicious use of AdjustPrivilegeToken

Description Indicator Process Target
Token: SeDebugPrivilege N/A C:\Users\Admin\AppData\Local\Temp\Client-buailt.exe N/A
Token: SeDebugPrivilege N/A C:\Windows\system32\SubDir\Client.exe N/A

Suspicious use of SetWindowsHookEx

Description Indicator Process Target
N/A N/A C:\Windows\system32\SubDir\Client.exe N/A

Uses Task Scheduler COM API

persistence

Processes

C:\Users\Admin\AppData\Local\Temp\Client-buailt.exe

"C:\Users\Admin\AppData\Local\Temp\Client-buailt.exe"

C:\Windows\SYSTEM32\schtasks.exe

"schtasks" /create /tn "Client Startup" /sc ONLOGON /tr "C:\Windows\system32\SubDir\Client.exe" /rl HIGHEST /f

C:\Windows\system32\SubDir\Client.exe

"C:\Windows\system32\SubDir\Client.exe"

C:\Windows\SYSTEM32\schtasks.exe

"schtasks" /create /tn "Client Startup" /sc ONLOGON /tr "C:\Windows\system32\SubDir\Client.exe" /rl HIGHEST /f

C:\Program Files (x86)\Microsoft\Edge\Application\msedge.exe

"C:\Program Files (x86)\Microsoft\Edge\Application\msedge.exe" --type=utility --utility-sub-type=asset_store.mojom.AssetStoreService --lang=en-US --service-sandbox-type=asset_store_service --no-appcompat-clear --mojo-platform-channel-handle=1348 --field-trial-handle=2284,i,15722001240173834669,15048020084704567542,262144 --variations-seed-version /prefetch:8

Network

Country Destination Domain Proto
US 8.8.8.8:53 183.142.211.20.in-addr.arpa udp
US 198.7.62.204:4782 tcp
US 8.8.8.8:53 218.135.221.88.in-addr.arpa udp
US 8.8.8.8:53 20.160.190.20.in-addr.arpa udp
US 8.8.8.8:53 chromewebstore.googleapis.com udp
US 8.8.8.8:53 chromewebstore.googleapis.com udp
US 8.8.8.8:53 chromewebstore.googleapis.com udp
US 8.8.8.8:53 chromewebstore.googleapis.com udp
NL 172.217.23.202:443 chromewebstore.googleapis.com tcp
US 8.8.8.8:53 202.23.217.172.in-addr.arpa udp
N/A 192.168.1.1:4782 tcp
US 8.8.8.8:53 50.23.12.20.in-addr.arpa udp
US 8.8.8.8:53 202.23.217.172.in-addr.arpa udp
US 8.8.8.8:53 58.55.71.13.in-addr.arpa udp
US 198.7.62.204:4782 tcp
US 8.8.8.8:53 219.135.221.88.in-addr.arpa udp
N/A 192.168.1.1:4782 tcp
US 8.8.8.8:53 40.134.221.88.in-addr.arpa udp
US 8.8.8.8:53 171.39.242.20.in-addr.arpa udp
US 8.8.8.8:53 149.220.183.52.in-addr.arpa udp
US 8.8.8.8:53 18.134.221.88.in-addr.arpa udp
US 198.7.62.204:4782 tcp
N/A 192.168.1.1:4782 tcp
US 8.8.8.8:53 0.205.248.87.in-addr.arpa udp
US 8.8.8.8:53 28.73.42.20.in-addr.arpa udp

Files

memory/1160-0-0x0000000000480000-0x00000000007C8000-memory.dmp

memory/1160-1-0x00007FF9840E0000-0x00007FF984BA1000-memory.dmp

memory/1160-2-0x000000001B380000-0x000000001B390000-memory.dmp

C:\Windows\System32\SubDir\Client.exe

MD5 67058a89ce6f3786bc28af9962d6202d
SHA1 57b66752526058f244ed0802d771b0b4d70432a9
SHA256 ee1544b6bb0a35c74391f821b94208443754ac5f7e01f03bc369eac3dd70b32d
SHA512 98a0cc78d49cba94cc5edd2804697391861cd0192ce10aeb93223ad05046a1418d1380c3a3cd7a1e17f0ab290e0a10cd60d3f0e8959ca4783d2eef7460a8ce62

memory/756-9-0x00007FF9840E0000-0x00007FF984BA1000-memory.dmp

memory/1160-10-0x00007FF9840E0000-0x00007FF984BA1000-memory.dmp

memory/756-11-0x000000001BF30000-0x000000001BF40000-memory.dmp

memory/756-12-0x000000001BE70000-0x000000001BEC0000-memory.dmp

memory/756-13-0x000000001C7F0000-0x000000001C8A2000-memory.dmp

memory/756-14-0x00007FF9840E0000-0x00007FF984BA1000-memory.dmp