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Trojan:Win32/C2Lop.S


Trojan:Win32/C2Lop.S is a trojan that modifies Web browser settings, adds browser bookmarks, and delivers pop-up advertisements.


What to do now

Manual removal is not recommended for this threat. To detect and remove this threat and other malicious software that may have been installed, run a full-system scan with an up-to-date antivirus product such as the Microsoft Safety Scanner (http://go.microsoft.com/fwlink/?LinkId=212742). For more information, see http://www.microsoft.com/protect/computer/viruses/vista.mspx.
 
Additional remediation instructions for Trojan:Win32/C2Lop.S
This threat may make lasting changes to an affected system’s configuration that will NOT be restored by detecting and removing this threat. For more information on returning an affected system to its pre-infected state, please see the following article/s: 

Threat behavior

Trojan:Win32/C2Lop.S is a trojan that modifies web browser settings, adds browser bookmarks, and delivers pop-up advertisements. 
Installation
When Trojan:Win32/C2Lop.S is run, it launches Internet Explorer from this file path:
  • %Program Files%\Internet Explorer\iexplore.exe
 
Next, this trojan injects its code into the running Internet Explorer process. 
 
Additionally, Trojan:Win32/C2Lop.S, it may make the following registry modifications:
 
Adds value: "MANAGER ONCE"
With data: "<random data>"
To subkey: HKCU\Software\web bows peakDumb
 
Adds value: "HRZR_PGYFRFFVBA"
With data: "¬s."
To subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\UserAssist\{5E6AB780-7743-11CF-A12B-00AA004AE837}\Count
Payload
Modifies browser settings
Trojan:Win32/C2Lop.S makes a number of changes to Internet Explorer settings by modifying the registry:
Sets value: "Window_Placement"
With data: ","
To subkey: HKCU\Software\Microsoft\Internet Explorer\Main
 
Sets value: "Locked"
With data: "1"
To subkey: HKCU\Software\Microsoft\Internet Explorer\Toolbar
 
Downloads and executes arbitrary files
This trojan may connect to a remote Web site to download and execute arbitrary files. The downloaded files are usually members of TrojanDownloader:Win32/Swizzor and Adware:Win32/Lop families. Once the downloaded files are successfully installed, unwanted pop-ups and advertisements may be displayed on the desktop of the affected machine.
 
Creates bookmarks 
This trojan may attempt to create the following bookmarks in the Internet Explorer Favorites folder and in the profile of the current user:
%UserProfile%\Favorites\Online Gaming
%UserProfile%\Favorites\Computers
%UserProfile%\Favorites\Games
%UserProfile%\Favorites\Internet
%UserProfile%\Favorites\Internet\Education
%UserProfile%\Favorites\Shopping Gifts
%UserProfile%\Favorites\Travel
%UserProfile%\Favorites\Cool Stuff
%UserProfile%\Favorites\Fun Stuff
%UserProfile%\Favorites\Cool Stuff\Home
%UserProfileE%\Favorites\Cool Stuff\Online Pharmacy
%UserProfile%\Favorites\Adult Items
%UserProfile%\Favorites\Adult Entertainment
%UserProfile%\Favorites\Dating
 
Modifies hosts file
Trojan:Win32/C2Lop.S  modifies the Windows Hosts file. The local Hosts file overrides the DNS resolution of a Web site URL to a particular IP address. Malicious software may make modifications to the Hosts file in order to redirect specified URLs to different IP addresses. Malware often modifies an affected machine's hosts file in order to stop users from accessing Web sites associated with particular security-related applications (such as antivirus for example). 
 
This trojan may attempt to modify the local hosts file to redirect Web browser connection attempts to domains associated with WinFixer to the localhost. The following hosts may be affected by these modifications:
bin.errorprotector.com 
br.errorsafe.com
br.winantivirus.com
br.winfixer.com
cdn.drivecleaner.com
cdn.errorsafe.com
cdn.winsoftware.com
de.errorsafe.com
de.winantivirus.com
download.cdn.drivecleaner.com
download.cdn.errorsafe.com
download.cdn.winsoftware.com
download.errorsafe.com
download.systemdoctor.com
download.winantispyware.com
download.windrivecleaner.com
download.winfixer.com
drivecleaner.com
dynamique.drivecleaner.com
errorprotector.com
errorsafe.com
es.winantivirus.com
fr.winantivirus.com
fr.winfixer.com
go.drivecleaner.com
go.errorsafe.com
go.winantispyware.com
go.winantivirus.com
hk.winantivirus.com
instlog.errorsafe.com
instlog.winantivirus.com
instlog.winfixer.com
jsp.drivecleaner.com
kb.errorsafe.com
kb.winantivirus.com
 
Analysis by Lena Lin

Symptoms

System changes
The following system changes may indicate the presence of this malware:
  • The presence of the following registry modifications:
  • Sets value: "Window_Placement"
    With data: ","
    To subkey: HKCU\Software\Microsoft\Internet Explorer\Main
     
    Sets value: "Locked"
    With data: "1"
    To subkey: HKCU\Software\Microsoft\Internet Explorer\Toolbar
     
    Adds value: "MANAGER ONCE"
    With data: "<random data>"
    To subkey: HKCU\Software\web bows peakDumb
     
    Sets value: "HRZR_PGYFRFFVBA"
    With data: "¬s."
    To subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\UserAssist\{5E6AB780-7743-11CF-A12B-00AA004AE837}\Count
  • Inability to contact the following hosts:
    bin.errorprotector.com 
    br.errorsafe.com
  • br.winantivirus.com
    br.winfixer.com
    cdn.drivecleaner.com
    cdn.errorsafe.com
    cdn.winsoftware.com
    de.errorsafe.com
    de.winantivirus.com
    download.cdn.drivecleaner.com
    download.cdn.errorsafe.com
    download.cdn.winsoftware.com
    download.errorsafe.com
    download.systemdoctor.com
    download.winantispyware.com
    download.windrivecleaner.com
    download.winfixer.com
    drivecleaner.com
    dynamique.drivecleaner.com
    errorprotector.com
    errorsafe.com
    es.winantivirus.com
    fr.winantivirus.com
    fr.winfixer.com
    go.drivecleaner.com
    go.errorsafe.com
    go.winantispyware.com
    go.winantivirus.com
    hk.winantivirus.com
    instlog.errorsafe.com
    instlog.winantivirus.com
    instlog.winfixer.com
    jsp.drivecleaner.com
    kb.errorsafe.com
    kb.winantivirus.com
  • The addition of the following bookmarks in the Internet Explorer favorites folder:
    %UserProfile%\Favorites\Online Gaming
  • %UserProfile%\Favorites\Computers
    %UserProfile%\Favorites\Games
    %UserProfile%\Favorites\Internet
    %UserProfile%\Favorites\Internet\Education
    %UserProfile%\Favorites\Shopping Gifts
    %UserProfile%\Favorites\Travel
    %UserProfile%\Favorites\Cool Stuff
    %UserProfile%\Favorites\Fun Stuff
    %UserProfile%\Favorites\Cool Stuff\Home
    %UserProfileE%\Favorites\Cool Stuff\Online Pharmacy
    %UserProfile%\Favorites\Adult Items
    %UserProfile%\Favorites\Adult Entertainment
    %UserProfile%\Favorites\Dating

Prevention


Alert level: Severe
First detected by definition: 1.71.511.0
Latest detected by definition: 1.85.666.0 and higher
First detected on: Dec 04, 2009
This entry was first published on: Dec 18, 2009
This entry was updated on: Apr 17, 2011

This threat is also detected as:
  • Trojan.Win32.Swizzor.c (Kaspersky)
  • Downloader.Swizzor (AVG)