BKDR_KULUOZ.WOY
TrojanDownloader:Win32/Kuluoz.D (Microsoft); Trojan.Asprox.B (Norton); Win32/TrojanDownloader.Zortob.B trojan (NOD32); W32/Zortob.BKZ!tr (Fortinet)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Backdoor
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
It executes commands from a remote malicious user, effectively compromising the affected system.
TECHNICAL DETAILS
Arrival Details
This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
Installation
This backdoor drops the following copies of itself into the affected system and executes them:
- %AppDataLocal%\{random filename}.exe
(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local on Windows Vista and 7.)
It adds the following processes:
- svchost.exe
It adds the following mutexes to ensure that only one of its copies runs at any one time:
- 2GVWNQJz1
It injects itself into the following processes as part of its memory residency routine:
- created svchost.exe
Autostart Technique
This backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random value 1} = "%AppDataLocal%\{random filename}.exe"
Other System Modifications
This backdoor adds the following registry keys:
HKEY_CURRENT_USER\Software\{random key}
It adds the following registry entries:
HKEY_CURRENT_USER\Software\{random key}
{random value 2} = "{hex values}"
Backdoor Routine
This backdoor executes the following commands from a remote malicious user:
- idl - sleep/idle
- run - download and execute file
- rem - uninstall malware from system
- rdl - update injected code in created svchost.exe and created registry entry
- red - update created registry entry
- upd - update copy of malware
- ear - update copy of malware and autorun registry entry
It connects to the following URL(s) to send and receive commands from a remote malicious user:
- http://{BLOCKED}.{BLOCKED}.122.67:443/{generated value}
- http://{BLOCKED}.{BLOCKED}.222.24:8080/{generated value}
- http://{BLOCKED}.{BLOCKED}.163.221:443/{generated value}
- http://{BLOCKED}.{BLOCKED}.50.228:443/{generated value}
- http://{BLOCKED}.{BLOCKED}.120.163:8080/generated value}
- http://{BLOCKED}.{BLOCKED}.17.8:8080/{generated value}
NOTES:
This malware checks if there is a running window with the following name:
- wireshark.exe
- Tfrmrpcap
- iptools.exe
- Iris - Version 5.59
- ProcessLasso_Notification_Class
- TSystemExplorerTrayForm.UnicodeClass
- PROCMON_WINDOW_CLASS
- PROCEXPL
- WdcWindow
- ProcessHacker
- 99929D61-1338-48B1-9433-D42A1D94F0D2-x64
- 99929D61-1338-48B1-9433-D42A1D94F0D2-x32
- 99929D61-1338-48B1-9433-D42A1D94F0D2
- Dumper
- Dumper64
- APISpy32Class
- VMwareDragDetWndClass
- VMwareSwitchUserControlClass
- vmtoolsd.exe
- prl_cc.exe
- prl_tools.exe
- SharedIntApp.exe
- VBoxTray.exe
- VBoxService.exe
- vmusrvc.exe
- vmsrvc.exe
SOLUTION
Step 1
Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.
Step 2
Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.
Step 3
Restart in Safe Mode
Step 4
Delete this registry value
Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- {random value 1} = "%AppDataLocal%\{random filename}.exe"
- {random value 1} = "%AppDataLocal%\{random filename}.exe"
Step 5
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_KULUOZ.WOY. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.
Step 6
The following created files/folders/registry keys/registry entries cannot be identified by the user since there are no reference values in the created key. The only way it can be identified is by comparing the present system information with a backup. Note that the said components do not have to be deleted since it won't be harmful to the system.
- In HKEY_CURRENT_USER\Software
- {random key}
- {random key}
- In HKEY_CURRENT_USER\Software\{random key}
- {random value 2} = "{hex values}"
- {random value 2} = "{hex values}"
Did this description help? Tell us how we did.