BKDR_XYSYL.B
Trojan:Win32/Zbot (Microsoft), Win32/TrojanDownloader.Wauchos.A trojan (ESET), Trojan.Win32.Generic!BT (Sunbelt), Troj/Backdr-HD (Sophos)
Windows 2000, Windows XP, Windows Server 2003
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Backdoor
Destructiveness: No
Encrypted:
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 modifies the Internet Explorer Zone Settings.
It deletes itself after execution.
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:
- {All User's Profile}\svchost.exe
- {All User's Profile}\Local Settings\Temp\{random file name}.{random extension}
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
SunJavaUpdateSched = "{All User's Profile}\svchost.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
{random number} = "{All User's Profile}\Local Settings\Temp\{random file name}.{random extension}"
Web Browser Home Page and Search Page Modification
This backdoor modifies the Internet Explorer Zone Settings.
Other Details
This backdoor connects to the following possibly malicious URL:
- http://{BLOCKED}e.com
- http://{BLOCKED}ep.ru
It 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
Scan your computer with your Trend Micro product and note files detected as BKDR_XYSYL.B
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
- SunJavaUpdateSched = "{All User's Profile}\svchost.exe"
- SunJavaUpdateSched = "{All User's Profile}\svchost.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
- {random number} = "{All User's Profile}\Local Settings\Temp\{random file name}.{random extension}"
- {random number} = "{All User's Profile}\Local Settings\Temp\{random file name}.{random extension}"
Step 5
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_XYSYL.B. 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.
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