buer | 0a6be94628e528a0354c71a800510ab89c442a5f3a428a49b729662d4d19529c

General

Target

DocumentPreview.exe
Size

228KB
MD5

801b2019d58f05ea3667603d3f2ff822
SHA1

ce0c63d9c1dd967d68158156e1c88e731fa25447
SHA256

0a6be94628e528a0354c71a800510ab89c442a5f3a428a49b729662d4d19529c
SHA512

8ef21833c493cb7bfad632df1842216dbcf7fa54fd87cb065d8d32fc120635b802e93481128f01d53bb7b5f32fa4d50122b4099f38cc348f9153a3b43be6131a

Score

10^/10

buer loader persistence

Malware Config

Extracted

Family

buer

C2

https://162.244.81.87/

http://162.244.81.87:8080/

Signatures

Buer
Buer is a new modular loader first seen in August 2019.
loader buer

Modifies WinLogon for persistence 2 TTPs 1 IoCs

persistence

Winlogon Helper DLL

T1004

Modify Registry

T1112

description	ioc	Process
Set value (str)	\REGISTRY\MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows NT\CurrentVersion\Winlogon\Shell = "explorer.exe, \"C:\\ProgramData\\12ab6e5e52ff0c5398ba\\gennt.exe\""	gennt.exe

Buer Loader 2 IoCs

Detects Buer loader in memory or disk.

resource	yara_rule
behavioral1/memory/1104-0-0x0000000000260000-0x000000000026C000-memory.dmp	buer
behavioral1/memory/1832-4-0x0000000000250000-0x000000000025C000-memory.dmp	buer

Executes dropped EXE 1 IoCs

pid	Process
1832	gennt.exe

Deletes itself 1 IoCs

pid	Process
1832	gennt.exe

Loads dropped DLL 1 IoCs

pid	Process
1104	DocumentPreview.exe

Enumerates connected drives 3 TTPs 24 IoCs

Attempts to read the root path of hard drives other than the default C: drive.

Query Registry

T1012

Peripheral Device Discovery

T1120

System Information Discovery

T1082

description	ioc	Process
File opened (read-only)	\??\X:	gennt.exe
File opened (read-only)	\??\E:	gennt.exe
File opened (read-only)	\??\I:	gennt.exe
File opened (read-only)	\??\J:	gennt.exe
File opened (read-only)	\??\M:	gennt.exe
File opened (read-only)	\??\N:	gennt.exe
File opened (read-only)	\??\O:	gennt.exe
File opened (read-only)	\??\Q:	gennt.exe
File opened (read-only)	\??\B:	gennt.exe
File opened (read-only)	\??\H:	gennt.exe
File opened (read-only)	\??\L:	gennt.exe
File opened (read-only)	\??\R:	gennt.exe
File opened (read-only)	\??\U:	gennt.exe
File opened (read-only)	\??\G:	gennt.exe
File opened (read-only)	\??\P:	gennt.exe
File opened (read-only)	\??\V:	gennt.exe
File opened (read-only)	\??\Z:	gennt.exe
File opened (read-only)	\??\A:	gennt.exe
File opened (read-only)	\??\F:	gennt.exe
File opened (read-only)	\??\K:	gennt.exe
File opened (read-only)	\??\S:	gennt.exe
File opened (read-only)	\??\T:	gennt.exe
File opened (read-only)	\??\W:	gennt.exe
File opened (read-only)	\??\Y:	gennt.exe

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

System Information Discovery
T1082

Program crash 1 IoCs

pid	pid_target	Process	procid_target
1808	1240	WerFault.exe	29

Suspicious behavior: EnumeratesProcesses 5 IoCs

pid	Process
1808	WerFault.exe
1808	WerFault.exe
1808	WerFault.exe
1808	WerFault.exe
1832	gennt.exe

Suspicious use of AdjustPrivilegeToken 1 IoCs

description	pid	Process
Token: SeDebugPrivilege	1808	WerFault.exe

Suspicious use of WriteProcessMemory 23 IoCs

description	pid	Process	procid_target
PID 1104 wrote to memory of 1832	1104	DocumentPreview.exe	27
PID 1104 wrote to memory of 1832	1104	DocumentPreview.exe	27
PID 1104 wrote to memory of 1832	1104	DocumentPreview.exe	27
PID 1104 wrote to memory of 1832	1104	DocumentPreview.exe	27
PID 1832 wrote to memory of 1240	1832	gennt.exe	29
PID 1832 wrote to memory of 1240	1832	gennt.exe	29
PID 1832 wrote to memory of 1240	1832	gennt.exe	29
PID 1832 wrote to memory of 1240	1832	gennt.exe	29
PID 1832 wrote to memory of 1240	1832	gennt.exe	29
PID 1832 wrote to memory of 1240	1832	gennt.exe	29
PID 1832 wrote to memory of 1240	1832	gennt.exe	29
PID 1832 wrote to memory of 1240	1832	gennt.exe	29
PID 1832 wrote to memory of 1240	1832	gennt.exe	29
PID 1832 wrote to memory of 1240	1832	gennt.exe	29
PID 1832 wrote to memory of 1240	1832	gennt.exe	29
PID 1240 wrote to memory of 1808	1240	secinit.exe	30
PID 1240 wrote to memory of 1808	1240	secinit.exe	30
PID 1240 wrote to memory of 1808	1240	secinit.exe	30
PID 1240 wrote to memory of 1808	1240	secinit.exe	30
PID 1832 wrote to memory of 1872	1832	gennt.exe	31
PID 1832 wrote to memory of 1872	1832	gennt.exe	31
PID 1832 wrote to memory of 1872	1832	gennt.exe	31
PID 1832 wrote to memory of 1872	1832	gennt.exe	31

C:\Users\Admin\AppData\Local\Temp\DocumentPreview.exe
"C:\Users\Admin\AppData\Local\Temp\DocumentPreview.exe"
1⤵
- Loads dropped DLL
- Suspicious use of WriteProcessMemory
PID:1104
- C:\ProgramData\12ab6e5e52ff0c5398ba\gennt.exe
  C:\ProgramData\12ab6e5e52ff0c5398ba\gennt.exe "C:\Users\Admin\AppData\Local\Temp\DocumentPreview.exe" ensgJJ
  2⤵
  - Modifies WinLogon for persistence
  - Executes dropped EXE
  - Deletes itself
  - Enumerates connected drives
  - Suspicious behavior: EnumeratesProcesses
  - Suspicious use of WriteProcessMemory
  PID:1832
- - C:\Windows\SysWOW64\secinit.exe
    C:\ProgramData\12ab6e5e52ff0c5398ba\gennt.exe
    3⤵
    - Suspicious use of WriteProcessMemory
    PID:1240
  - - C:\Windows\SysWOW64\WerFault.exe
      C:\Windows\SysWOW64\WerFault.exe -u -p 1240 -s 144
      4⤵
      Program crash
      Suspicious behavior: EnumeratesProcesses
      Suspicious use of AdjustPrivilegeToken
      PID:1808
- - C:\Windows\SysWOW64\cmd.exe
    "C:\Windows\System32\cmd.exe" powershell.exe -Command "& {Add-MpPreference -ExclusionPath C:\ProgramData\12ab6e5e52ff0c5398ba}"
    3⤵
    PID:1872

Network

MITRE ATT&CK Enterprise v6

Initial Access

Execution

Persistence

Winlogon Helper DLL

1

T1004

Privilege Escalation

Defense Evasion

Modify Registry

1

T1112

Credential Access

Discovery

Peripheral Device Discovery

Query Registry

System Information Discovery

2

T1082

Lateral Movement

Collection

Command and Control

Exfiltration

Impact

Replay Monitor

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Downloads

memory/1104-0-0x0000000000260000-0x000000000026C000-memory.dmp

Filesize
48KB

Download
memory/1808-8-0x0000000001FB0000-0x0000000001FC1000-memory.dmp

Filesize
68KB

Download
memory/1808-11-0x0000000002600000-0x0000000002611000-memory.dmp

Filesize
68KB

Download
memory/1832-4-0x0000000000250000-0x000000000025C000-memory.dmp

Filesize
48KB

Download

Analysis

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