f0e98cc9e77c4b14e67aae84dcb833f9d40a536a253cca74409fa195cb35154e

General

Target

csrss.exe
Size

2.1MB
MD5

2a9be7e5bc1de20522b4e71159159956
SHA1

53b6034d122211f7e3937d5f61325d3211842848
SHA256

f0e98cc9e77c4b14e67aae84dcb833f9d40a536a253cca74409fa195cb35154e
SHA512

af42bc88d9de45a575ce63be246706e98e0135738b63d1f02d28fb024487112736be72f7869822ceb8a16617b43a5235d41358b090d223e9913a1cfacd60e7a0

Score

10^/10

evasion persistence

Malware Config

Signatures

Modifies WinLogon for persistence 2 TTPs 5 IoCs

persistence

Winlogon Helper DLL

T1004

Modify Registry

T1112

Processes:

csrss.exe

description	ioc	process
Set value (str)	\REGISTRY\MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows NT\CurrentVersion\Winlogon\Shell = "explorer.exe, \"C:\\Windows\\System32\\kbdarmph\\winlogon.exe\", \"C:\\odt\\taskhostw.exe\", \"C:\\PerfLogs\\SppExtComObj.exe\", \"C:\\Program Files (x86)\\Windows Mail\\SearchUI.exe\", \"C:\\Users\\Admin\\AppData\\Local\\Temp\\sa.9WZDNCRCWFTB_0_0010_.Public.InstallAgent\\csrss.exe\""	csrss.exe
Set value (str)	\REGISTRY\MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows NT\CurrentVersion\Winlogon\Shell = "explorer.exe, \"C:\\Windows\\System32\\kbdarmph\\winlogon.exe\""	csrss.exe
Set value (str)	\REGISTRY\MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows NT\CurrentVersion\Winlogon\Shell = "explorer.exe, \"C:\\Windows\\System32\\kbdarmph\\winlogon.exe\", \"C:\\odt\\taskhostw.exe\""	csrss.exe
Set value (str)	\REGISTRY\MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows NT\CurrentVersion\Winlogon\Shell = "explorer.exe, \"C:\\Windows\\System32\\kbdarmph\\winlogon.exe\", \"C:\\odt\\taskhostw.exe\", \"C:\\PerfLogs\\SppExtComObj.exe\""	csrss.exe
Set value (str)	\REGISTRY\MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows NT\CurrentVersion\Winlogon\Shell = "explorer.exe, \"C:\\Windows\\System32\\kbdarmph\\winlogon.exe\", \"C:\\odt\\taskhostw.exe\", \"C:\\PerfLogs\\SppExtComObj.exe\", \"C:\\Program Files (x86)\\Windows Mail\\SearchUI.exe\""	csrss.exe

Identifies VirtualBox via ACPI registry values (likely anti-VM) 2 TTPs
evasion

Query Registry
T1012

Virtualization/Sandbox Evasion
T1497
Executes dropped EXE 1 IoCs

Processes:

csrss.exe

pid process

3160 csrss.exe

pid	process
3160	csrss.exe

Checks BIOS information in registry 2 TTPs 4 IoCs

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

Query Registry

T1012

System Information Discovery

T1082

Processes:

csrss.execsrss.exe

description	ioc	process
Key value queried	\REGISTRY\MACHINE\HARDWARE\DESCRIPTION\System\VideoBiosVersion	csrss.exe
Key value queried	\REGISTRY\MACHINE\HARDWARE\DESCRIPTION\System\SystemBiosVersion	csrss.exe
Key value queried	\REGISTRY\MACHINE\HARDWARE\DESCRIPTION\System\VideoBiosVersion	csrss.exe
Key value queried	\REGISTRY\MACHINE\HARDWARE\DESCRIPTION\System\SystemBiosVersion	csrss.exe

Identifies Wine through registry keys 2 TTPs 2 IoCs

Wine is a compatibility layer capable of running Windows applications, which can be used as sandboxing environment.

evasion

Query Registry

T1012

Virtualization/Sandbox Evasion

T1497

Processes:

csrss.execsrss.exe

description	ioc	process
Key opened	\REGISTRY\USER\S-1-5-21-3686645723-710336880-414668232-1000\Software\Wine	csrss.exe
Key opened	\REGISTRY\USER\S-1-5-21-3686645723-710336880-414668232-1000\Software\Wine	csrss.exe

Adds Run key to start application 2 TTPs 10 IoCs

persistence

Registry Run Keys / Startup Folder

T1060

Modify Registry

T1112

Processes:

csrss.exe

description	ioc	process
Set value (str)	\REGISTRY\USER\S-1-5-21-3686645723-710336880-414668232-1000\Software\Microsoft\Windows\CurrentVersion\Run\csrss = "\"C:\\Users\\Admin\\AppData\\Local\\Temp\\sa.9WZDNCRCWFTB_0_0010_.Public.InstallAgent\\csrss.exe\""	csrss.exe
Set value (str)	\REGISTRY\MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Run\csrss = "\"C:\\Users\\Admin\\AppData\\Local\\Temp\\sa.9WZDNCRCWFTB_0_0010_.Public.InstallAgent\\csrss.exe\""	csrss.exe
Set value (str)	\REGISTRY\USER\S-1-5-21-3686645723-710336880-414668232-1000\Software\Microsoft\Windows\CurrentVersion\Run\taskhostw = "\"C:\\odt\\taskhostw.exe\""	csrss.exe
Set value (str)	\REGISTRY\MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Run\taskhostw = "\"C:\\odt\\taskhostw.exe\""	csrss.exe
Set value (str)	\REGISTRY\MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Run\SppExtComObj = "\"C:\\PerfLogs\\SppExtComObj.exe\""	csrss.exe
Set value (str)	\REGISTRY\USER\S-1-5-21-3686645723-710336880-414668232-1000\Software\Microsoft\Windows\CurrentVersion\Run\SearchUI = "\"C:\\Program Files (x86)\\Windows Mail\\SearchUI.exe\""	csrss.exe
Set value (str)	\REGISTRY\MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Run\SearchUI = "\"C:\\Program Files (x86)\\Windows Mail\\SearchUI.exe\""	csrss.exe
Set value (str)	\REGISTRY\USER\S-1-5-21-3686645723-710336880-414668232-1000\Software\Microsoft\Windows\CurrentVersion\Run\winlogon = "\"C:\\Windows\\System32\\kbdarmph\\winlogon.exe\""	csrss.exe
Set value (str)	\REGISTRY\MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Run\winlogon = "\"C:\\Windows\\System32\\kbdarmph\\winlogon.exe\""	csrss.exe
Set value (str)	\REGISTRY\USER\S-1-5-21-3686645723-710336880-414668232-1000\Software\Microsoft\Windows\CurrentVersion\Run\SppExtComObj = "\"C:\\PerfLogs\\SppExtComObj.exe\""	csrss.exe

Looks up external IP address via web service 2 IoCs
Uses a legitimate IP lookup service to find the infected system's external IP.

Processes:

flow ioc

18 ipinfo.io
17 ipinfo.io

flow	ioc
18	ipinfo.io
17	ipinfo.io

Drops file in System32 directory 3 IoCs

Processes:

csrss.exe

description	ioc	process
File created	C:\Windows\SysWOW64\kbdarmph\winlogon.exe	csrss.exe
File opened for modification	C:\Windows\SysWOW64\kbdarmph\winlogon.exe	csrss.exe
File created	C:\Windows\SysWOW64\kbdarmph\cc11b995f2a76da408ea6a601e682e64743153ad	csrss.exe

Suspicious use of NtSetInformationThreadHideFromDebugger 2 IoCs

Processes:

csrss.execsrss.exe

pid process

2184 csrss.exe
3160 csrss.exe

pid	process
2184	csrss.exe
3160	csrss.exe

Drops file in Program Files directory 2 IoCs

Processes:

csrss.exe

description	ioc	process
File created	C:\Program Files (x86)\Windows Mail\SearchUI.exe	csrss.exe
File created	C:\Program Files (x86)\Windows Mail\dab4d89cac03ec27dbe47b361df763dc3f848f6c	csrss.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

Processes:

schtasks.exeschtasks.exeschtasks.exeschtasks.exeschtasks.exe

pid process

3848 schtasks.exe
2912 schtasks.exe
3860 schtasks.exe
1988 schtasks.exe
3116 schtasks.exe
Modifies registry class 1 IoCs

Processes:

csrss.exe

description ioc process

Key created \REGISTRY\USER\S-1-5-21-3686645723-710336880-414668232-1000_Classes\Local Settings csrss.exe
Runs ping.exe 1 TTPs 1 IoCs

Remote System Discovery
T1018

Processes:

PING.EXE

pid process

2800 PING.EXE
Suspicious behavior: EnumeratesProcesses 6 IoCs

Processes:

csrss.execsrss.exe

pid process

2184 csrss.exe
2184 csrss.exe
2184 csrss.exe
3160 csrss.exe
3160 csrss.exe
3160 csrss.exe
Suspicious behavior: GetForegroundWindowSpam 1 IoCs

Processes:

csrss.exe

pid process

3160 csrss.exe
Suspicious use of AdjustPrivilegeToken 2 IoCs

Processes:

csrss.execsrss.exe

description pid process

Token: SeDebugPrivilege 2184 csrss.exe
Token: SeDebugPrivilege 3160 csrss.exe

pid	process
3848	schtasks.exe
2912	schtasks.exe
3860	schtasks.exe
1988	schtasks.exe
3116	schtasks.exe

description	ioc	process
Key created	\REGISTRY\USER\S-1-5-21-3686645723-710336880-414668232-1000_Classes\Local Settings	csrss.exe

pid	process
2800	PING.EXE

pid	process
2184	csrss.exe
2184	csrss.exe
2184	csrss.exe
3160	csrss.exe
3160	csrss.exe
3160	csrss.exe

pid	process
3160	csrss.exe

description	pid	process
Token: SeDebugPrivilege	2184	csrss.exe
Token: SeDebugPrivilege	3160	csrss.exe

Suspicious use of WriteProcessMemory 27 IoCs

Processes:

csrss.execmd.exe

description	pid	process	target process
PID 2184 wrote to memory of 3848	2184	csrss.exe	schtasks.exe
PID 2184 wrote to memory of 3848	2184	csrss.exe	schtasks.exe
PID 2184 wrote to memory of 3848	2184	csrss.exe	schtasks.exe
PID 2184 wrote to memory of 2912	2184	csrss.exe	schtasks.exe
PID 2184 wrote to memory of 2912	2184	csrss.exe	schtasks.exe
PID 2184 wrote to memory of 2912	2184	csrss.exe	schtasks.exe
PID 2184 wrote to memory of 3860	2184	csrss.exe	schtasks.exe
PID 2184 wrote to memory of 3860	2184	csrss.exe	schtasks.exe
PID 2184 wrote to memory of 3860	2184	csrss.exe	schtasks.exe
PID 2184 wrote to memory of 1988	2184	csrss.exe	schtasks.exe
PID 2184 wrote to memory of 1988	2184	csrss.exe	schtasks.exe
PID 2184 wrote to memory of 1988	2184	csrss.exe	schtasks.exe
PID 2184 wrote to memory of 3116	2184	csrss.exe	schtasks.exe
PID 2184 wrote to memory of 3116	2184	csrss.exe	schtasks.exe
PID 2184 wrote to memory of 3116	2184	csrss.exe	schtasks.exe
PID 2184 wrote to memory of 1568	2184	csrss.exe	cmd.exe
PID 2184 wrote to memory of 1568	2184	csrss.exe	cmd.exe
PID 2184 wrote to memory of 1568	2184	csrss.exe	cmd.exe
PID 1568 wrote to memory of 752	1568	cmd.exe	chcp.com
PID 1568 wrote to memory of 752	1568	cmd.exe	chcp.com
PID 1568 wrote to memory of 752	1568	cmd.exe	chcp.com
PID 1568 wrote to memory of 2800	1568	cmd.exe	PING.EXE
PID 1568 wrote to memory of 2800	1568	cmd.exe	PING.EXE
PID 1568 wrote to memory of 2800	1568	cmd.exe	PING.EXE
PID 1568 wrote to memory of 3160	1568	cmd.exe	csrss.exe
PID 1568 wrote to memory of 3160	1568	cmd.exe	csrss.exe
PID 1568 wrote to memory of 3160	1568	cmd.exe	csrss.exe

C:\Users\Admin\AppData\Local\Temp\csrss.exe
"C:\Users\Admin\AppData\Local\Temp\csrss.exe"
1⤵
- Modifies WinLogon for persistence
- Checks BIOS information in registry
- Identifies Wine through registry keys
- Adds Run key to start application
- Drops file in System32 directory
- Suspicious use of NtSetInformationThreadHideFromDebugger
- Drops file in Program Files directory
- Modifies registry class
- Suspicious behavior: EnumeratesProcesses
- Suspicious use of AdjustPrivilegeToken
- Suspicious use of WriteProcessMemory
PID:2184

C:\Windows\SysWOW64\schtasks.exe
"schtasks" /create /tn "winlogon" /sc ONLOGON /tr "'C:\Windows\System32\kbdarmph\winlogon.exe'" /rl HIGHEST /f
2⤵
- Creates scheduled task(s)
PID:3848

C:\Windows\SysWOW64\schtasks.exe
"schtasks" /create /tn "taskhostw" /sc ONLOGON /tr "'C:\odt\taskhostw.exe'" /rl HIGHEST /f
2⤵
- Creates scheduled task(s)
PID:2912

C:\Windows\SysWOW64\schtasks.exe
"schtasks" /create /tn "SppExtComObj" /sc ONLOGON /tr "'C:\PerfLogs\SppExtComObj.exe'" /rl HIGHEST /f
2⤵
- Creates scheduled task(s)
PID:3860

C:\Windows\SysWOW64\schtasks.exe
"schtasks" /create /tn "SearchUI" /sc ONLOGON /tr "'C:\Program Files (x86)\Windows Mail\SearchUI.exe'" /rl HIGHEST /f
2⤵
- Creates scheduled task(s)
PID:1988

C:\Windows\SysWOW64\schtasks.exe
"schtasks" /create /tn "csrss" /sc ONLOGON /tr "'C:\Users\Admin\AppData\Local\Temp\sa.9WZDNCRCWFTB_0_0010_.Public.InstallAgent\csrss.exe'" /rl HIGHEST /f
2⤵
- Creates scheduled task(s)
PID:3116

C:\Windows\SysWOW64\cmd.exe
"C:\Windows\System32\cmd.exe" /C "C:\Users\Public\FLHmpYhDet.bat"
2⤵
- Suspicious use of WriteProcessMemory
PID:1568

C:\Windows\SysWOW64\chcp.com
chcp 65001
3⤵
PID:752

C:\Windows\SysWOW64\PING.EXE
ping -n 5 localhost
3⤵
- Runs ping.exe
PID:2800

C:\Users\Admin\AppData\Local\Temp\sa.9WZDNCRCWFTB_0_0010_.Public.InstallAgent\csrss.exe
"C:\Users\Admin\AppData\Local\Temp\sa.9WZDNCRCWFTB_0_0010_.Public.InstallAgent\csrss.exe"
3⤵
- Executes dropped EXE
- Checks BIOS information in registry
- Identifies Wine through registry keys
- Suspicious use of NtSetInformationThreadHideFromDebugger
- Suspicious behavior: EnumeratesProcesses
- Suspicious behavior: GetForegroundWindowSpam
- Suspicious use of AdjustPrivilegeToken
PID:3160

Network

MITRE ATT&CK Enterprise v6

Initial Access

Execution

Scheduled Task

1

T1053

Persistence

Registry Run Keys / Startup Folder

Scheduled Task

Winlogon Helper DLL

Privilege Escalation

Scheduled Task

1

T1053

Defense Evasion

Modify Registry

2

T1112

Virtualization/Sandbox Evasion

2

T1497

Credential Access

Discovery

Query Registry

3

T1012

Remote System Discovery

1

T1018

System Information Discovery

2

T1082

Virtualization/Sandbox Evasion

2

T1497

Lateral Movement

Collection

Command and Control

Exfiltration

Impact

Replay Monitor

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Downloads

C:\Users\Admin\AppData\Local\Microsoft\CLR_v4.0_32\UsageLogs\csrss.exe.log
MD5
5ffad73168c231b45cb78e9d9f20ddc9

SHA1
10d2e22118fddb531b038d6a2bbaf4912f67956a

SHA256
09002a9002494e8ab1ead3f7db4fdd1fc611094e7f2c1e04c6fb1c2f7dc3767a

SHA512
b18a369de64c03825dd865781655ca34e55683489239ce0149dc0c116f3d0249462720843b1bf261f557ba6d5fd5d4cb69d873fe9995b0c9f1b37017b4c395a4

Download Submit
C:\Users\Admin\AppData\Local\Temp\sa.9WZDNCRCWFTB_0_0010_.Public.InstallAgent\csrss.exe
MD5
2a9be7e5bc1de20522b4e71159159956

SHA1
53b6034d122211f7e3937d5f61325d3211842848

SHA256
f0e98cc9e77c4b14e67aae84dcb833f9d40a536a253cca74409fa195cb35154e

SHA512
af42bc88d9de45a575ce63be246706e98e0135738b63d1f02d28fb024487112736be72f7869822ceb8a16617b43a5235d41358b090d223e9913a1cfacd60e7a0

Download Submit
C:\Users\Admin\AppData\Local\Temp\sa.9WZDNCRCWFTB_0_0010_.Public.InstallAgent\csrss.exe
MD5
2a9be7e5bc1de20522b4e71159159956

SHA1
53b6034d122211f7e3937d5f61325d3211842848

SHA256
f0e98cc9e77c4b14e67aae84dcb833f9d40a536a253cca74409fa195cb35154e

SHA512
af42bc88d9de45a575ce63be246706e98e0135738b63d1f02d28fb024487112736be72f7869822ceb8a16617b43a5235d41358b090d223e9913a1cfacd60e7a0

Download Submit
C:\Users\Public\FLHmpYhDet.bat
MD5
f2393dee9928e1dbc4beb474e74e9de0

SHA1
16ec9ffd8666b33e7061b5336266cd60c674be69

SHA256
a39957aa9bf4e9f18c80119f093ec9cf7b87c5c51147034b205901413b48adb3

SHA512
6fd97eb7bf58cd6b635d7930ec59a5561c0b839e68e857e320bafd7d3276f20d1996554e38f42aa942a725926e334aca236cdd6f0feb119916e0b2fc3405cdb9

Download Submit
memory/752-128-0x0000000000000000-mapping.dmp

Download
memory/1568-126-0x0000000000000000-mapping.dmp

Download
memory/1988-124-0x0000000000000000-mapping.dmp

Download
memory/2184-119-0x0000000007B01000-0x0000000007B02000-memory.dmp

Filesize
4KB

Download
memory/2184-114-0x0000000077300000-0x000000007748E000-memory.dmp

Filesize
1.6MB

Download
memory/2184-120-0x0000000008700000-0x0000000008701000-memory.dmp

Filesize
4KB

Download
memory/2184-118-0x0000000007880000-0x0000000007881000-memory.dmp

Filesize
4KB

Download
memory/2184-117-0x0000000008100000-0x0000000008101000-memory.dmp

Filesize
4KB

Download
memory/2184-115-0x0000000000150000-0x0000000000151000-memory.dmp

Filesize
4KB

Download
memory/2800-129-0x0000000000000000-mapping.dmp

Download
memory/2912-122-0x0000000000000000-mapping.dmp

Download
memory/3116-125-0x0000000000000000-mapping.dmp

Download
memory/3160-133-0x0000000077300000-0x000000007748E000-memory.dmp

Filesize
1.6MB

Download
memory/3160-130-0x0000000000000000-mapping.dmp

Download
memory/3160-135-0x0000000001130000-0x0000000001131000-memory.dmp

Filesize
4KB

Download
memory/3160-139-0x0000000007501000-0x0000000007502000-memory.dmp

Filesize
4KB

Download
memory/3160-141-0x0000000004EF0000-0x0000000004EF7000-memory.dmp

Filesize
28KB

Download
memory/3160-142-0x0000000008E60000-0x0000000008E61000-memory.dmp

Filesize
4KB

Download
memory/3848-121-0x0000000000000000-mapping.dmp

Download
memory/3860-123-0x0000000000000000-mapping.dmp

Download

Analysis

Sharing

General

Malware Config

Signatures

Processes

Network

MITRE ATT&CK Enterprise v6

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Downloads