BKDR_CYCBOT.TX

 Analysis by: Roland Marco Dela Paz

 ALIASES:

Microsoft : Backdoor:Win32/Cycbot.B; Symantec : Backdoor.Cycbot!gen2

 PLATFORM:

Windows 2000, XP, Server 2003

 OVERALL RISK RATING:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW


This backdoor may be dropped by other malware. It may be unknowingly downloaded by a user while visiting malicious websites.

  TECHNICAL DETAILS

File Size:

Varies

File Type:

PE

Memory Resident:

Yes

Initial Samples Received Date:

12 Dec 2010

Payload:

Connects to URLs/Ips, Steals information, Downloads files

Arrival Details

This backdoor may be dropped by other malware.

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This backdoor drops the following non-malicious file:

  • %Application Data%\A1B2.580

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = explorer.exe,%Application Data%\dwm.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
conhost = %Application Data%\Microsoft\conhost.exe

It modifies the following registry entry(ies) to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
load = %User Temp%\csrss.exe

Other System Modifications

This backdoor adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ProxyServer = http=127.0.0.1:{random port}

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ProxyEnable = 1

(Note: The default value data of the said registry entry is 0.)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Hardware Profiles\0001\Software\
Microsoft\windows\CurrentVersion\
Internet Settings
ProxyEnable = 1

(Note: The default value data of the said registry entry is 0.)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Hardware Profiles\Current\Software\
Microsoft\windows\CurrentVersion\
Internet Settings
ProxyEnable = 1

(Note: The default value data of the said registry entry is 0.)

HKEY_CURRENT_CONFIG\Software\Microsoft\
windows\CurrentVersion\Internet Settings
ProxyEnable = 1

(Note: The default value data of the said registry entry is 0.)

Dropping Routine

This backdoor drops the following file(s), into which it saves gathered information:

  • %Application Data%\Microsoft\stor.cfg

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

Stolen Information

This backdoor sends the gathered information via HTTP POST to the following URL:

  • http://{BLOCKED}fic.cn/pics/23.jpg

Other Details

This backdoor does the following:

  • Acts as a proxy server to intercept requests of the following internet browsers and point them to the proxy server on a random port that it sets in the registry:
    • Internet Explorer
    • Mozilla Firefox
    • Opera
  • Monitors user's Internet browsing activity and check for the following strings of popular websites such as search engines and social networking sites to steal information:
    • &query=
    • .2mdn.
    • .abmr.
    • .adtechus.
    • .aol.
    • .atdmt.
    • .atwola.
    • .autodatadirect.
    • .bing.net
    • .dartsearch.
    • .doubleclick.
    • .ggpht.
    • .google
    • .ivwbox.
    • .mapquestapi.
    • .microsoft.
    • .opera.
    • .tacoda.
    • .thawte.
    • .tlowdb.
    • .truveo.
    • .virtualearth.
    • .wsod.
    • .yimg.com
    • .ypcdn.
    • /complete/search
    • /gen_204
    • /images
    • /imglanding
    • ?query=
    • amazon
    • aol/search
    • aolcdn.
    • aolsvc.
    • bing.com
    • bing.com/search
    • blogger
    • brightcove.com
    • err069
    • facebook
    • flickr
    • google
    • google.
    • http%3A%2F%2F
    • mapq.st
    • scorecardresearch.com
    • search.aol.
    • search.yahoo.com/search
    • searcht2.aol.
    • start=0
    • suche.aol.
    • twitter
    • wikipedia
    • yahoo.
    • yahoo.com
    • youtube
  • Connects to the following URLs to download an updated copy of itself and possibly other malicious files:
    • http://{BLOCKED}.com
    • http://{BLOCKED}.com
    • http://{BLOCKED}mpage.com
    • http://{BLOCKED}ompage.com
    • http://{BLOCKED}mywebconnection.com
    • http://{BLOCKED}archive.com
    • http://{BLOCKED}driversonline.com
    • http://{BLOCKED}wcounter.com
    • http://{BLOCKED}emonitoring.com
    • http://{BLOCKED}sstore.com
    It does this by sending the following GET requests to the above mentioned servers:
    • images/im133.jpg?tq={parameter}
    • images/im134.jpg?tq={parameter}
    • images/im135.jpg?tq={parameter}
    It also sends requests to the following websites where non-malicious images can be downloaded. Since the extension names of the file downloaded which are mostly .jpg are similar to the GET request to the above malicious servers, this routine may prevent easy analysis of the requests done by this backdoor:
    • http://freeonlinedatingtips.net/images/dating1.jpg
    • http://sharewareconnection.com/images/ubar_0.jpg
    • http://sharewareconnection.com/images/ubar_1.jpg
    • http://sharewareconnection.com/im/s.cgi
    • http://www.internetsecure.com/images/ismerch.gif
    • http://136136.com/lb5000/non-cgi/images/leoca.gif
    • http://136136.com/LB5000/CGI-BIN/topic.cgi
    • http://136136.com/LB5000/CGI-BIN/s.cgi
    • http://pcdocpro.com/images/logo-1.jpg
    • http://pcdocpro.com/images/logo-2.jpg
    • http://historykillerpro.com/img/eslogo.gif
    • http://blenderartists.org/external/Banners/facebook.jpg
    • http://blenderartists.org/external/Banners/facebook2.jpg
  • Saves the files it downloads which may be an updated copy of itself or other malicious files, using the following names:
    • %User Temp%\csrss.exe
    • %Application Data%\dwm.exe
    • %Application Data%\Microsoft\conhost.exe

  SOLUTION

Minimum Scan Engine:

8.900

VSAPI PATTERN File:

7.696.01

VSAPI PATTERN Date:

12 Dec 2010

VSAPI PATTERN Date:

12/12/2010 12:00:00 AM

VSAPI OPR PATTERN File:

7.697.00

VSAPI OPR PATTERN Date:

12 Dec 2010

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

Identify and terminate files detected as BKDR_CYCBOT.TX

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

Delete this registry value

[ Learn More ]

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\Internet Settings
    • ProxyServer = http=127.0.0.1:55636
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
    • Shell = explorer.exe,C:\Documents and Settings\winxp.BATCH57.000\Application Data\dwm.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • conhost = C:\Documents and Settings\winxp.BATCH57.000\Application Data\Microsoft\conhost.exe

Step 4

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In
    To: ws\CurrentVersion\Internet Settings
    • From: ProxyEnable = 1
      To: ProxyEnable = 0
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
    • From: load = C:\DOCUME~1\WINXPB~1.000\LOCALS~1\Temp\csrss.exe
      To: load = {null}
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Hardware Profiles\0001\Software\Microsoft\windows\CurrentVersion\Internet Settings
    • From: ProxyEnable = 1
      To: ProxyEnable = 0
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Hardware Profiles\Current\Software\Microsoft\windows\CurrentVersion\Internet Settings
    • From: ProxyEnable = 1
      To: ProxyEnable = 0
  • In HKEY_CURRENT_CONFIG\Software\Microsoft\windows\CurrentVersion\Internet Settings
    • From: ProxyEnable = 1
      To: ProxyEnable = 0
      • From:

Step 5

Search and delete these components

[ Learn More ]
There may be some components that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result. %Application Data%\A1B2.580
%Application Data%\Microsoft\stor.cfg

Step 6

Scan your computer with your Trend Micro product to delete files detected as BKDR_CYCBOT.TX. 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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