dcrat | 99b234ed5fcab5f1e2ebbc0a26fd5e94a3efa69fadb275065592ea7cba636e16

General

Target
b9a42f557b8e8d48bd5b061f8e714af9.exe
Size 1.2MB
Sample210911-lbbehsbbg8
SHA256 99b234ed5fcab5f1e2ebbc0a26fd5e94a3efa69fadb275065592ea7cba636e16
MD5 b9a42f557b8e8d48bd5b061f8e714af9
SHA1 f591e3bb267304fb5261465552f80910306c9ec7
SHA512 fb0577b150e658d6d182b41de88da72f26af1dc33171de54832a952defae1df8f239c8f112c6e32a26341402548a2f4965b490e4d152bb593dd4c7b9d38c4b98
MD5 SHA1 SHA512

Score

10^/10

dcrat infostealer persistence rat spyware stealer

Malware Config

Signatures

DcRat
DarkCrystal(DC) is a new .NET RAT active since June 2019 capable of loading additional plugins.
rat infostealer dcrat

Process spawned unexpected child process 5 IoCs

This typically indicates the parent process was compromised via an exploit or macro.

description	pid	pid_target	Process	procid_target
Parent C:\Windows\system32\wbem\wmiprvse.exe is not expected to spawn this process	1152	424	schtasks.exe	16
Parent C:\Windows\system32\wbem\wmiprvse.exe is not expected to spawn this process	1280	424	schtasks.exe	16
Parent C:\Windows\system32\wbem\wmiprvse.exe is not expected to spawn this process	4024	424	schtasks.exe	16
Parent C:\Windows\system32\wbem\wmiprvse.exe is not expected to spawn this process	2012	424	schtasks.exe	16
Parent C:\Windows\system32\wbem\wmiprvse.exe is not expected to spawn this process	1456	424	schtasks.exe	16

DCRat Payload 6 IoCs

Detects payload of DCRat, commonly dropped by NSIS installers.

rat

resource	yara_rule
behavioral2/files/0x000400000001ab2c-116.dat	dcrat
behavioral2/files/0x000400000001ab2c-119.dat	dcrat
behavioral2/files/0x000400000001ab30-125.dat	dcrat
behavioral2/files/0x000400000001ab30-126.dat	dcrat
behavioral2/files/0x000600000001ab48-131.dat	dcrat
behavioral2/files/0x000600000001ab48-132.dat	dcrat

Downloads MZ/PE file

Executes dropped EXE 3 IoCs

pid	Process
3808	dlihost.exe
3664	savesruntimeBrokerFontwin.exe
1548	explorer.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

Adds Run key to start application 2 TTPs 5 IoCs

persistence

Registry Run Keys / Startup Folder

T1060

Modify Registry

T1112

description	ioc	Process
Set value (str)	\REGISTRY\MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\dllhost = "\"C:\\Windows\\System32\\tpmvscmgrsvr\\dllhost.exe\""	savesruntimeBrokerFontwin.exe
Set value (str)	\REGISTRY\MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\explorer = "\"C:\\Windows\\regedit\\explorer.exe\""	savesruntimeBrokerFontwin.exe
Set value (str)	\REGISTRY\MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\spoolsv = "\"C:\\Windows\\System32\\dnscacheugc\\spoolsv.exe\""	savesruntimeBrokerFontwin.exe
Set value (str)	\REGISTRY\MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\audiodg = "\"C:\\Windows\\System32\\iasrecst\\audiodg.exe\""	savesruntimeBrokerFontwin.exe
Set value (str)	\REGISTRY\MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\savesruntimeBrokerFontwin = "\"C:\\savesruntimeBroker\\bB37mtqgliH1SYemgnxw\\savesruntimeBrokerFontwin.exe\""	savesruntimeBrokerFontwin.exe

Drops file in System32 directory 7 IoCs

description	ioc	Process
File created	C:\Windows\System32\iasrecst\42af1c969fbb7b2ae36b0e06bea61fc9a154b4af	savesruntimeBrokerFontwin.exe
File created	C:\Windows\System32\tpmvscmgrsvr\dllhost.exe	savesruntimeBrokerFontwin.exe
File created	C:\Windows\System32\tpmvscmgrsvr\5940a34987c99120d96dace90a3f93f329dcad63	savesruntimeBrokerFontwin.exe
File created	C:\Windows\System32\dnscacheugc\spoolsv.exe	savesruntimeBrokerFontwin.exe
File created	C:\Windows\System32\dnscacheugc\f3b6ecef712a24f33798f5d2fb3790c3d9b894c4	savesruntimeBrokerFontwin.exe
File created	C:\Windows\System32\iasrecst\audiodg.exe	savesruntimeBrokerFontwin.exe
File opened for modification	C:\Windows\System32\iasrecst\audiodg.exe	savesruntimeBrokerFontwin.exe

Drops file in Windows directory 2 IoCs

description	ioc	Process
File created	C:\Windows\regedit\explorer.exe	savesruntimeBrokerFontwin.exe
File created	C:\Windows\regedit\7a0fd90576e08807bde2cc57bcf9854bbce05fe3	savesruntimeBrokerFontwin.exe

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

System Information Discovery
T1082

Creates scheduled task(s) 1 TTPs 5 IoCs

Schtasks is often used by malware for persistence or to perform post-infection execution.

persistence

Scheduled Task

T1053

pid	Process
1152	schtasks.exe
1280	schtasks.exe
4024	schtasks.exe
2012	schtasks.exe
1456	schtasks.exe

Modifies registry class 3 IoCs

description	ioc	Process
Key created	\REGISTRY\USER\S-1-5-21-2559286294-2439613352-4032193287-1000_Classes\Local Settings\Software\Microsoft\Windows\CurrentVersion\WorkFolders	rundll32.exe
Key created	\REGISTRY\USER\S-1-5-21-2559286294-2439613352-4032193287-1000_Classes\Local Settings	dlihost.exe
Key created	\REGISTRY\USER\S-1-5-21-2559286294-2439613352-4032193287-1000_Classes\Local Settings	b9a42f557b8e8d48bd5b061f8e714af9.exe

Suspicious behavior: EnumeratesProcesses 6 IoCs

pid	Process
3664	savesruntimeBrokerFontwin.exe
1548	explorer.exe
1548	explorer.exe
1548	explorer.exe
1548	explorer.exe
1548	explorer.exe

Suspicious behavior: GetForegroundWindowSpam 1 IoCs

pid	Process
1548	explorer.exe

Suspicious use of AdjustPrivilegeToken 2 IoCs

description	pid	Process
Token: SeDebugPrivilege	3664	savesruntimeBrokerFontwin.exe
Token: SeDebugPrivilege	1548	explorer.exe

Suspicious use of WriteProcessMemory 13 IoCs

description	pid	Process	procid_target
PID 2248 wrote to memory of 3808	2248	b9a42f557b8e8d48bd5b061f8e714af9.exe	69
PID 2248 wrote to memory of 3808	2248	b9a42f557b8e8d48bd5b061f8e714af9.exe	69
PID 2248 wrote to memory of 3808	2248	b9a42f557b8e8d48bd5b061f8e714af9.exe	69
PID 3808 wrote to memory of 2636	3808	dlihost.exe	71
PID 3808 wrote to memory of 2636	3808	dlihost.exe	71
PID 3808 wrote to memory of 2636	3808	dlihost.exe	71
PID 2636 wrote to memory of 592	2636	WScript.exe	72
PID 2636 wrote to memory of 592	2636	WScript.exe	72
PID 2636 wrote to memory of 592	2636	WScript.exe	72
PID 592 wrote to memory of 3664	592	cmd.exe	74
PID 592 wrote to memory of 3664	592	cmd.exe	74
PID 3664 wrote to memory of 1548	3664	savesruntimeBrokerFontwin.exe	80
PID 3664 wrote to memory of 1548	3664	savesruntimeBrokerFontwin.exe	80

C:\Users\Admin\AppData\Local\Temp\b9a42f557b8e8d48bd5b061f8e714af9.exe
"C:\Users\Admin\AppData\Local\Temp\b9a42f557b8e8d48bd5b061f8e714af9.exe"
1⤵
- Modifies registry class
- Suspicious use of WriteProcessMemory
PID:2248
- C:\Users\Admin\AppData\Local\Temp\dlihost.exe
  C:\Users\Admin\AppData\Local\Temp\dlihost.exe
  2⤵
  - Executes dropped EXE
  - Modifies registry class
  - Suspicious use of WriteProcessMemory
  PID:3808
- - C:\Windows\SysWOW64\WScript.exe
    "C:\Windows\System32\WScript.exe" "C:\savesruntimeBroker\bB37mtqgliH1SYemgnxw.vbe"
    3⤵
    - Suspicious use of WriteProcessMemory
    PID:2636
  - - C:\Windows\SysWOW64\cmd.exe
      C:\Windows\system32\cmd.exe /c ""C:\savesruntimeBroker\IW2ru7jY87FyQpz9to.bat" "
      4⤵
      Suspicious use of WriteProcessMemory
      PID:592
    - - C:\savesruntimeBroker\savesruntimeBrokerFontwin.exe
        
        "C:\savesruntimeBroker\savesruntimeBrokerFontwin.exe"
        5⤵
        Executes dropped EXE
        Adds Run key to start application
        Drops file in System32 directory
        Drops file in Windows directory
        Suspicious behavior: EnumeratesProcesses
        Suspicious use of AdjustPrivilegeToken
        Suspicious use of WriteProcessMemory
        
        PID:3664
      - C:\Windows\regedit\explorer.exe
        
        "C:\Windows\regedit\explorer.exe"
        6⤵
        Executes dropped EXE
        Suspicious behavior: EnumeratesProcesses
        Suspicious behavior: GetForegroundWindowSpam
        Suspicious use of AdjustPrivilegeToken
        
        PID:1548

C:\Windows\System32\rundll32.exe
C:\Windows\System32\rundll32.exe C:\Windows\System32\shell32.dll,SHCreateLocalServerRunDll {9aa46009-3ce0-458a-a354-715610a075e6} -Embedding
1⤵
- Modifies registry class
PID:4060

C:\Windows\system32\schtasks.exe
schtasks.exe /create /tn "audiodg" /sc ONLOGON /tr "'C:\Windows\System32\iasrecst\audiodg.exe'" /rl HIGHEST /f
1⤵
- Process spawned unexpected child process
- Creates scheduled task(s)
PID:1152

C:\Windows\system32\schtasks.exe
schtasks.exe /create /tn "savesruntimeBrokerFontwin" /sc ONLOGON /tr "'C:\savesruntimeBroker\bB37mtqgliH1SYemgnxw\savesruntimeBrokerFontwin.exe'" /rl HIGHEST /f
1⤵
- Process spawned unexpected child process
- Creates scheduled task(s)
PID:1280

C:\Windows\system32\schtasks.exe
schtasks.exe /create /tn "dllhost" /sc ONLOGON /tr "'C:\Windows\System32\tpmvscmgrsvr\dllhost.exe'" /rl HIGHEST /f
1⤵
- Process spawned unexpected child process
- Creates scheduled task(s)
PID:4024

C:\Windows\system32\schtasks.exe
schtasks.exe /create /tn "explorer" /sc ONLOGON /tr "'C:\Windows\regedit\explorer.exe'" /rl HIGHEST /f
1⤵
- Process spawned unexpected child process
- Creates scheduled task(s)
PID:2012

C:\Windows\system32\schtasks.exe
schtasks.exe /create /tn "spoolsv" /sc ONLOGON /tr "'C:\Windows\System32\dnscacheugc\spoolsv.exe'" /rl HIGHEST /f
1⤵
- Process spawned unexpected child process
- Creates scheduled task(s)
PID:1456