TROJ_CARBERP.YTW
Trojan:Win32/Carberp.gen!B, (Microsoft); Generic-FAOM!E330E096E08E (McAfee); Trojan-Dropper.Win32.Injector.kamm (Kaspersky); Mal/Kelihos-A (Sophos); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse Crypt3.DOH (AVG)
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.
It deletes itself after execution.
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:
- %System Root%\91328.bat
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
It adds the following registry keys:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Control\Session Manager\AppCertDlls
HKEY_CURRENT_USER\Software\AppDataLow\
Software\Microsoft\Internet Explorer\
Security\AntiPhishing\7926A403-841D-130B-56BD-F8F7EA41AC1B
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\Session Manager\AppCertDlls
chknhost = "%Windows%\blasfmon.dll"
HKEY_CURRENT_USER\Software\AppDataLow\
Software\Microsoft\Internet Explorer\
Security\AntiPhishing\7926A403-841D-130B-56BD-F8F7EA41AC1B
UserFile = "{random values}"
Other Details
This Trojan deletes itself after execution.
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\System\CurrentControlSet\Control\Session Manager
- AppCertDlls
- In HKEY_CURRENT_USER\Software\AppDataLow\Software\Microsoft\Internet Explorer\Security\AntiPhishing
- 7926A403-841D-130B-56BD-F8F7EA41AC1B
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\SYSTEM\ControlSet001\Control\Session Manager\AppCertDlls
- chknhost = "%Windows%\blasfmon.dll"
- In HKEY_CURRENT_USER\Software\AppDataLow\Software\Microsoft\Internet Explorer\Security\AntiPhishing\7926A403-841D-130B-56BD-F8F7EA41AC1B
- UserFile = "{random values}"
Step 4
Scan your computer with your Trend Micro product to delete files detected as TROJ_CARBERP.YTW. 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 5
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.
- %System Root%\91328.bat
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