TROJ_DROPPER.ZYP
Windows 2000, Windows XP, Windows Server 2003
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Trojan
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
TECHNICAL DETAILS
Arrival Details
This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
Other System Modifications
This Trojan deletes the following files:
- %Windows%\tasks\sa01.dat
- %System%\syslog.dat
- %System%\RpcSvc.psd
- %System Root%\Net-Temp.ini
- %Temp%\temp1.exe
- %Temp%\temp2.exe
(Note: %Windows% is the Windows folder, which is usually C:\Windows.. %System% is the Windows system folder, which is usually C:\Windows\System32.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp.)
It adds the following registry keys:
HKEY_LOCAL_MACHINE\SOFTWARE\27733056
HKEY_LOCAL_MACHINE\SOFTWARE\27733056\
Parameters
HKEY_LOCAL_MACHINE\SOFTWARE\284886040
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\27733056\
Parameters
ServiceDll = "%System%\RpcSvc.psd"
HKEY_LOCAL_MACHINE\SOFTWARE\284886040
imgsvc = "StiSvc,RpcSvc"
It modifies the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\RemoteAccess\RouterManagers\
Ip
DLLPath = "%System Root%\2021300.dll"
(Note: The default value data of the said registry entry is {random values}.)
Dropping Routine
This Trojan drops the following files:
- %Windows%\setupball.bmp
- %System%\drivers\ahnurla.sys
- %Windows%\svchost.exe
- %System Root%\2021300.dll
- %System Root%\NT_Path.jpg
- %Windows%\image.jpg
- %System%\RpcSvc.psd
(Note: %Windows% is the Windows folder, which is usually C:\Windows.. %System% is the Windows system folder, which is usually C:\Windows\System32.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
Other Details
This Trojan connects to the following possibly malicious URL:
- http://www.{BLOCKED}m.net/001.jpg
- http://www.{BLOCKED}l.co.kr/001.jpg
- http://www.{BLOCKED}orea.com/bbs2/001.jpg
- http://www.{BLOCKED}r.co.kr/bbs2/data/001.jpg
- http://www.{BLOCKED}5.co.kr/nbbs/001.jpg
- http://adw.{BLOCKED}4.co.kr/001.jpg
This report is generated via an automated analysis system.
SOLUTION
Step 1
Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.
Step 2
Delete this registry key
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_LOCAL_MACHINE\SOFTWARE
- 27733056
- In HKEY_LOCAL_MACHINE\SOFTWARE\27733056
- Parameters
- In HKEY_LOCAL_MACHINE\SOFTWARE
- 284886040
Step 3
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_LOCAL_MACHINE\SOFTWARE\27733056\Parameters
- ServiceDll = "%System%\RpcSvc.psd"
- In HKEY_LOCAL_MACHINE\SOFTWARE\284886040
- imgsvc = "StiSvc,RpcSvc"
Step 4
Restore these modified registry values
Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\RemoteAccess\RouterManagers\Ip
- From: DLLPath = "%System Root%\2021300.dll"
To: DLLPath = ""{random values}""
- From: DLLPath = "%System Root%\2021300.dll"
Step 5
Search and delete these components
- %Windows%\setupball.bmp
- %System%\drivers\ahnurla.sys
- %Windows%\svchost.exe
- %System Root%\2021300.dll
- %System Root%\NT_Path.jpg
- %Windows%\image.jpg
- %System%\RpcSvc.psd
Step 6
Scan your computer with your Trend Micro product to delete files detected as TROJ_DROPPER.ZYP. 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 7
Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.
- %Windows%\tasks\sa01.dat
- %System%\syslog.dat
- %System%\RpcSvc.psd
- %System Root%\Net-Temp.ini
- %Temp%\temp1.exe
- %Temp%\temp2.exe
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