oski | c30ce79d7b5b0708dc03f1532fa89afd4efd732531cb557dc31fe63acd5bc1ce

General

Target
gunzipped.exe
Size 411KB
Sample220106-hqya2sbdck
SHA256 c30ce79d7b5b0708dc03f1532fa89afd4efd732531cb557dc31fe63acd5bc1ce
MD5 c2301b62539adcba29dcf6a3200bd017
SHA1 fd80f7e8e32661d5ec12e7a901f22a9ed82e17a7
SHA512 80fef672e7f48640c585f12408025ea06c67344551bb4638e10120ceb30da7e888b18a52aabd209186315c1476da905afe15d5cb68a7d7e266954de16e813037
MD5 SHA1 SHA512

Score

10^/10

oski discovery infostealer spyware stealer suricata

Malware Config

Extracted

Family

oski

C2

http://2.56.57.108/osk/

Signatures

Oski
Oski is an infostealer targeting browser data, crypto wallets.
infostealer oski
suricata: ET MALWARE Suspicious Zipped Filename in Outbound POST Request (Passwords.txt)
suricata: ET MALWARE Suspicious Zipped Filename in Outbound POST Request (Passwords.txt)
suricata
suricata: ET MALWARE Vidar/Arkei/Megumin/Oski Stealer Data Exfil
suricata: ET MALWARE Vidar/Arkei/Megumin/Oski Stealer Data Exfil
suricata
suricata: ET MALWARE Vidar/Arkei/Megumin/Oski Stealer HTTP POST Pattern
suricata: ET MALWARE Vidar/Arkei/Megumin/Oski Stealer HTTP POST Pattern
suricata
Downloads MZ/PE file

Loads dropped DLL 4 IoCs

pid	Process
3796	gunzipped.exe
380	gunzipped.exe
380	gunzipped.exe
380	gunzipped.exe

Reads user/profile data of web browsers 2 TTPs
Infostealers often target stored browser data, which can include saved credentials etc.
spyware stealer

Data from Local System
T1005

Credentials in Files
T1081
Accesses cryptocurrency files/wallets, possible credential harvesting 2 TTPs
spyware

Data from Local System
T1005

Credentials in Files
T1081
Checks installed software on the system 1 TTPs
Looks up Uninstall key entries in the registry to enumerate software on the system.
discovery

Query Registry
T1012
Enumerates physical storage devices 1 TTPs
Attempts to interact with connected storage/optical drive(s). Likely ransomware behaviour.

System Information Discovery
T1082

Checks processor information in registry 2 TTPs 1 IoCs

Processor information is often read in order to detect sandboxing environments.

Query Registry

T1012

System Information Discovery

T1082

description	ioc	Process
Key value queried	\REGISTRY\MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor\0\ProcessorNameString	gunzipped.exe

Kills process with taskkill 1 IoCs

evasion

pid	Process
3648	taskkill.exe

Suspicious use of AdjustPrivilegeToken 1 IoCs

description	pid	Process
Token: SeDebugPrivilege	3648	taskkill.exe

Suspicious use of WriteProcessMemory 15 IoCs

description	pid	Process	procid_target
PID 3796 wrote to memory of 380	3796	gunzipped.exe	69
PID 3796 wrote to memory of 380	3796	gunzipped.exe	69
PID 3796 wrote to memory of 380	3796	gunzipped.exe	69
PID 3796 wrote to memory of 380	3796	gunzipped.exe	69
PID 3796 wrote to memory of 380	3796	gunzipped.exe	69
PID 3796 wrote to memory of 380	3796	gunzipped.exe	69
PID 3796 wrote to memory of 380	3796	gunzipped.exe	69
PID 3796 wrote to memory of 380	3796	gunzipped.exe	69
PID 3796 wrote to memory of 380	3796	gunzipped.exe	69
PID 380 wrote to memory of 1484	380	gunzipped.exe	70
PID 380 wrote to memory of 1484	380	gunzipped.exe	70
PID 380 wrote to memory of 1484	380	gunzipped.exe	70
PID 1484 wrote to memory of 3648	1484	cmd.exe	72
PID 1484 wrote to memory of 3648	1484	cmd.exe	72
PID 1484 wrote to memory of 3648	1484	cmd.exe	72

C:\Users\Admin\AppData\Local\Temp\gunzipped.exe
"C:\Users\Admin\AppData\Local\Temp\gunzipped.exe"
1⤵
- Loads dropped DLL
- Suspicious use of WriteProcessMemory
PID:3796
- C:\Users\Admin\AppData\Local\Temp\gunzipped.exe
  "C:\Users\Admin\AppData\Local\Temp\gunzipped.exe"
  2⤵
  - Loads dropped DLL
  - Checks processor information in registry
  - Suspicious use of WriteProcessMemory
  PID:380
- - C:\Windows\SysWOW64\cmd.exe
    "C:\Windows\System32\cmd.exe" /c taskkill /pid 380 & erase C:\Users\Admin\AppData\Local\Temp\gunzipped.exe & RD /S /Q C:\\ProgramData\\531228198980345\\* & exit
    3⤵
    - Suspicious use of WriteProcessMemory
    PID:1484
  - - C:\Windows\SysWOW64\taskkill.exe
      taskkill /pid 380
      4⤵
      Kills process with taskkill
      Suspicious use of AdjustPrivilegeToken
      PID:3648

Network

MITRE ATT&CK Enterprise v6

Initial Access

Execution

Persistence

Privilege Escalation

Defense Evasion

Credential Access

Credentials in Files

2

T1081

Discovery

Query Registry

2

T1012

System Information Discovery

2

T1082

Lateral Movement

Collection

Data from Local System

2

T1005

Command and Control

Exfiltration

Impact

Replay Monitor

Loading Replay Monitor...

Downloads

memory/380-117-0x00000000007B0000-0x00000000007E8000-memory.dmp

Download

memory/380-120-0x00000000007B0000-0x00000000007E8000-memory.dmp