buer | e212e5bc428a0bca4615205f07c10d4e57dc881a2f32a9b8aeec040169435aa1

General

Target

DocumentPreview.exe
Size

146KB
MD5

db3c2530d727bac602e6c41cb3e60562
SHA1

0d62d5a5fba84c1e826591f27892466a1cd59257
SHA256

e212e5bc428a0bca4615205f07c10d4e57dc881a2f32a9b8aeec040169435aa1
SHA512

03e25d32a262c88ec2cf9303b7835da93b321a1d2a092531c96df8d95065944250f63c075792ca72b6d2a12d60c492782ba516712fbca0bf3b0239477b6b06e8

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\\ae99cb89d6941a0b3431\\gennt.exe\""	gennt.exe

Buer Loader 1 IoCs

Detects Buer loader in memory or disk.

resource	yara_rule
behavioral2/memory/2904-0-0x00000000001D0000-0x00000000001DC000-memory.dmp	buer

Executes dropped EXE 1 IoCs

pid	Process
3720	gennt.exe

Deletes itself 1 IoCs

pid	Process
3720	gennt.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)	\??\N:	gennt.exe
File opened (read-only)	\??\U:	gennt.exe
File opened (read-only)	\??\V:	gennt.exe
File opened (read-only)	\??\A:	gennt.exe
File opened (read-only)	\??\G:	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)	\??\X:	gennt.exe
File opened (read-only)	\??\B:	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)	\??\H:	gennt.exe
File opened (read-only)	\??\O:	gennt.exe
File opened (read-only)	\??\P:	gennt.exe
File opened (read-only)	\??\Y:	gennt.exe
File opened (read-only)	\??\Z:	gennt.exe
File opened (read-only)	\??\E:	gennt.exe
File opened (read-only)	\??\F:	gennt.exe
File opened (read-only)	\??\L:	gennt.exe
File opened (read-only)	\??\Q:	gennt.exe
File opened (read-only)	\??\R:	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
3912	4000	WerFault.exe	76

Suspicious behavior: EnumeratesProcesses 15 IoCs

pid	Process
3912	WerFault.exe
3912	WerFault.exe
3912	WerFault.exe
3912	WerFault.exe
3912	WerFault.exe
3912	WerFault.exe
3912	WerFault.exe
3912	WerFault.exe
3912	WerFault.exe
3912	WerFault.exe
3912	WerFault.exe
3912	WerFault.exe
3912	WerFault.exe
3720	gennt.exe
3720	gennt.exe

Suspicious use of AdjustPrivilegeToken 3 IoCs

description	pid	Process
Token: SeRestorePrivilege	3912	WerFault.exe
Token: SeBackupPrivilege	3912	WerFault.exe
Token: SeDebugPrivilege	3912	WerFault.exe

Suspicious use of WriteProcessMemory 16 IoCs

description	pid	Process	procid_target
PID 2904 wrote to memory of 3720	2904	DocumentPreview.exe	74
PID 2904 wrote to memory of 3720	2904	DocumentPreview.exe	74
PID 2904 wrote to memory of 3720	2904	DocumentPreview.exe	74
PID 3720 wrote to memory of 4000	3720	gennt.exe	76
PID 3720 wrote to memory of 4000	3720	gennt.exe	76
PID 3720 wrote to memory of 4000	3720	gennt.exe	76
PID 3720 wrote to memory of 4000	3720	gennt.exe	76
PID 3720 wrote to memory of 4000	3720	gennt.exe	76
PID 3720 wrote to memory of 4000	3720	gennt.exe	76
PID 3720 wrote to memory of 4000	3720	gennt.exe	76
PID 3720 wrote to memory of 4000	3720	gennt.exe	76
PID 3720 wrote to memory of 4000	3720	gennt.exe	76
PID 3720 wrote to memory of 4000	3720	gennt.exe	76
PID 3720 wrote to memory of 3740	3720	gennt.exe	79
PID 3720 wrote to memory of 3740	3720	gennt.exe	79
PID 3720 wrote to memory of 3740	3720	gennt.exe	79

C:\Users\Admin\AppData\Local\Temp\DocumentPreview.exe
"C:\Users\Admin\AppData\Local\Temp\DocumentPreview.exe"
1⤵
- Suspicious use of WriteProcessMemory
PID:2904
- C:\ProgramData\ae99cb89d6941a0b3431\gennt.exe
  C:\ProgramData\ae99cb89d6941a0b3431\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:3720
- - C:\Windows\SysWOW64\secinit.exe
    C:\ProgramData\ae99cb89d6941a0b3431\gennt.exe
    3⤵
    PID:4000
  - - C:\Windows\SysWOW64\WerFault.exe
      C:\Windows\SysWOW64\WerFault.exe -u -p 4000 -s 352
      4⤵
      Program crash
      Suspicious behavior: EnumeratesProcesses
      Suspicious use of AdjustPrivilegeToken
      PID:3912
- - C:\Windows\SysWOW64\cmd.exe
    "C:\Windows\System32\cmd.exe" powershell.exe -Command "& {Add-MpPreference -ExclusionPath C:\ProgramData\ae99cb89d6941a0b3431}"
    3⤵
    PID:3740

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/2904-0-0x00000000001D0000-0x00000000001DC000-memory.dmp

Filesize
48KB

Download
memory/3912-12-0x0000000004C30000-0x0000000004C31000-memory.dmp

Filesize
4KB

Download
memory/3912-6-0x00000000043C0000-0x00000000043C1000-memory.dmp

Filesize
4KB

Download

Analysis

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