TROJ_NECURS.XSH
Trojan:Win32/Necurs.gen!A (Microsoft); BackDoor-FHK (McAfee); Trojan-Dropper.Win32.Necurs.bbt (Kaspersky); Trojan.Win32.Generic.pak!cobra (Sunbelt)
Windows 2000, Windows XP, Windows Server 2003
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
151,552 bytes
EXE
Yes
13 Jun 2013
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.
Installation
This Trojan drops the following copies of itself into the affected system:
- %Windows%\Installer\{6C0C17D1-E841-FBA1-82BC-DEC45D6A2C0A}\syshost.exe
(Note: %Windows% is the Windows folder, which is usually C:\Windows.)
It creates the following folders:
- %Windows%\Installer\{6C0C17D1-E841-FBA1-82BC-DEC45D6A2C0A}
(Note: %Windows% is the Windows folder, which is usually C:\Windows.)
Autostart Technique
This Trojan adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
syshost32 = "%Windows%\Installer\{6C0C17D1-E841-FBA1-82BC-DEC45D6A2C0A}\syshost.exe"
Other System Modifications
This Trojan deletes the following files:
- {malware path and file name}.tmp
- %Windows%\Installer\{6C0C17D1-E841-FBA1-82BC-DEC45D6A2C0A}\syshost.exe:Zone.Identifier
(Note: %Windows% is the Windows folder, which is usually C:\Windows.)
This report is generated via an automated analysis system.
SOLUTION
9.300
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
Restart in Safe Mode
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\Microsoft\Windows\CurrentVersion\Run
- syshost32 = "%Windows%\Installer\{6C0C17D1-E841-FBA1-82BC-DEC45D6A2C0A}\syshost.exe"
Step 4
Search and delete this folder
- %Windows%\Installer\{6C0C17D1-E841-FBA1-82BC-DEC45D6A2C0A}
Step 5
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_NECURS.XSH. 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
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.
- {malware path and file name}.tmp
- %Windows%\Installer\{6C0C17D1-E841-FBA1-82BC-DEC45D6A2C0A}\syshost.exe:Zone.Identifier
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