TROJ_COSMU.WA
Trojan:Win32/Malagent (Microsoft), Trojan.Win32.Cosmu.yls (Kaspersky)
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Trojan
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
This Trojan connects to a malicious URL through via 443 to send information such as computer name, user name, IP address, and subnet mask among others.
However, as of this writing, the said site is inaccessible.
This Trojan may be dropped by other malware.
It executes then deletes itself afterward.
TECHNICAL DETAILS
43,520 bytes
EXE
Yes
18 May 2010
Steals information
Arrival Details
This Trojan may be dropped by other malware.
Installation
This Trojan drops the following copies of itself into the affected system:
- %System%\winui.exe
- %System%\dllcache\winui.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)
It drops the following component file(s):
- %System%\usbmgr.dll - encrypted code to be injected to explorer.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)
It executes then deletes itself afterward.
It injects itself into the following processes as part of its memory residency routine:
- explorer.exe
It terminates the execution of the copy it initially executed and executes the copy it drops instead.
Autostart Technique
This Trojan adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\Currentversion\Policies\
Explorer\Run
utiluser = "winui.exe"
NOTES:
It connects to the site {BLOCKED}l.trendmicro.org.tw via port 443 to send the following information:
- Computer name
- User name
- IP address
- Subnet mask
- Windows version
- Current locale
- Total Physical Memory
However, as of this writing, the said site is inaccessible.
SOLUTION
8.900
7.176.11
18 May 2010
7.177.00
19 May 2010
Step 1
For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.
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_CURRENT_USER\Software\Microsoft\Windows\Currentversion\Policies\Explorer\Run
- utiluser="winui.exe"
- utiluser="winui.exe"
Step 4
Search and delete this file
Step 5
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_COSMU.WA. 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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