Analysis by: Marfel Tiamzon
ALIASES:

McAfee: W32/Sdbot.worm!lg; Fsecure: Worm.Generic.345229; Kaspersky: Worm.Win32.Ngrbot.fwi; Sophos: Mal/Generic-L

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This worm arrives by connecting affected removable drives to a system. It arrives via removable drives. It may be dropped by other malware.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

It prevents users from visiting antivirus-related websites that contain specific strings. It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size: 167,936 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 30 Sep 2011
Payload: Compromises system security

Arrival Details

This worm arrives by connecting affected removable drives to a system.

It arrives via removable drives.

It may be dropped by other malware.

Installation

This worm drops the following copies of itself into the affected system:

  • %System Root%\Documents and Settings\Administrator\Application Data\{random characters}.exe

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • FvLQ49IlzIyLjj6m
  • e621ca05-Mutex

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{malware file name} = %System Root%\Documents and Settings\Administrator\Application Data\{malware file name}.exe

Propagation

This worm creates the following folders in all removable drives:

  • {drive letter}:\RECYCLER

It drops the following copy(ies) of itself in all removable drives:

  • {drive letter}:\RECYCLER\{random characters}.exe

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

[AutoRun]
;{garbage characters}
shellexecute=RECYCLER\{malware file name}.exe
;{garbage characters}
icon=shell32.dll,7
;{garbage characters}
shell\open\command=RECYCLER\{malware file name}.exe
;{garbage characters}
action=Open folder to view files
;{garbage characters}
shell\explore\command=RECYCLER\{malware file name}.exe
;{garbage characters}
useautoplay=1

It sends messages that contain links to sites hosting remote copies of itself using the following instant-messaging (IM) applications:

  • Pidgin
  • Windows Live Communicator
  • MSN Messenger
  • mIRC

Backdoor Routine

This worm connects to the following URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED}ot-servers.org

Other Details

This worm connects to the following URL(s) to get the affected system's IP address:

  • http://api.wipmania.com/

It prevents users from visiting antivirus-related websites that contain the following strings:

  • avast.
  • avira.
  • bitdefender.
  • bullguard.
  • clamav.
  • comodo.
  • emsisoft.
  • eset.
  • f-secure.
  • fortinet.
  • garyshood.
  • gdatasoftware.
  • heck.tc
  • iseclab.
  • jotti.
  • kaspersky.
  • lavasoft.
  • malwarebytes.
  • mcafee.
  • norman.
  • norton.
  • novirusthanks.
  • onecare.live.
  • onlinemalwarescanner.
  • pandasecurity.
  • precisesecurity.
  • sophos.
  • sunbeltsoftware.
  • symantec
  • threatexpert.
  • trendmicro.
  • virscan.
  • virus.
  • virusbuster.nprotect.
  • viruschief.
  • virustotal.
  • webroot.

It deletes the initially executed copy of itself

NOTES:

It drops the file {removable drive letter}:\RECYCLER\Desktop.ini to change the icon of the RECYCLER folder into the Recycle Bin icon.

It drops shortcut files pointing to the copy of itself in removable drives. These dropped .LNK files use the names of the folders located on the said drives for their file names. It then sets the attributes of the original folders to Hidden to trick the user into clicking the .LNK files.

This worm monitors the Internet activities of the infected system to steal user credentials if the user visits websites with the following strings:

  • *&password=*
  • *&txtPassword=*
  • *.moneybookers.*/*login.pl
  • *1and1.com/xml/config*
  • *4shared.com/login*
  • *:2082/login*
  • *:2083/login*
  • *:2086/login*
  • *:2222/CMD_LOGIN*
  • *alertpay.com/login*
  • *aol.*/*login.psp*
  • *bcointernacional*login*
  • *bigstring.*/*index.php*
  • *clave=*
  • *depositfiles.*/*/login*
  • *dotster.com/*login*
  • *dyndns*/account*
  • *enom.com/login*
  • *facebook.*/login.php*
  • *fastmail.*/mail/*
  • *fileserv.com/login*
  • *filesonic.com/*login*
  • *FLN-Password=*
  • *freakshare.com/login*
  • *gmx.*/*FormLogin*
  • *godaddy.com/login*
  • *google.*/*ServiceLoginAuth*
  • *hackforums.*/member.php
  • *hotfile.com/login*
  • *letitbit.net*
  • *login.live.*/*post.srf*
  • *login.Pass=*
  • *login.yahoo.*/*login*
  • *login_pass=*
  • *login_password=*
  • *LoginPassword=*
  • *loginUserPassword=*
  • *mediafire.com/*login*
  • *megaupload.*/*login*
  • *members*.iknowthatgirl*/members*
  • *members.brazzers.com*
  • *moniker.com/*Login*
  • *namecheap.com/*login*
  • *netflix.com/*ogin*
  • *netload.in/index*
  • *no-ip*/login*
  • *officebanking.cl/*login.asp*
  • *oron.com/login*
  • *pas=*
  • *pass=*
  • *Passwd=*
  • *password=*
  • *password]=*
  • *paypal.*/webscr?cmd=_login-submit*
  • *pw=*
  • *runescape*/*weblogin*
  • *screenname.aol.*/login.psp*
  • *secure.logmein.*/*logincheck*
  • *sendspace.com/login*
  • *service=youtube*
  • *signin.ebay*SignIn
  • *sms4file.com/*/signin-do*
  • *speedyshare.com/login*
  • *steampowered*/login*
  • *TextfieldPassword=*
  • *thepiratebay.org/login*
  • *torrentleech.org/*login*
  • *twitter.com/sessions
  • *txtpass=*
  • *uploaded.to/*login*
  • *uploading.com/*login*
  • *vip-file.com/*/signin-do*
  • *webnames.ru/*user_login*
  • *what.cd/login*
  • *whcms*dologin*
  • *youporn.*/login*
  • 1and1
  • 4shared
  • Alertpay
  • Bcointernacional
  • BigString
  • Brazzers
  • clave
  • Depositfiles
  • Dotster
  • DynDNS
  • email
  • EmailName
  • Facebook
  • Fastmail
  • Fileserve
  • Filesonic
  • FLN-Password
  • FLN-UserName
  • Freakshare
  • Gmail
  • Godaddy
  • Hackforums
  • Hotfile
  • IKnowThatGirl
  • Letitbit
  • login
  • login.Pass
  • login.User
  • login[password]
  • login[user name]
  • login_email
  • login_pass
  • login_password
  • loginId
  • loginname
  • LoginPassword
  • loginUserName
  • loginUserPassword
  • LogMeIn
  • Mediafire
  • Megaupload
  • Moneybookers
  • Moniker
  • Namecheap
  • Netflix
  • Netload
  • numeroTarjeta
  • OfficeBanking
  • passwd
  • Password
  • PayPal
  • quick_password
  • quick_username
  • Runescape
  • screenname
  • Sendspace
  • session[password]
  • session[username_or_email]
  • Sms4file
  • Speedyshare
  • Steam
  • TextfieldEmail
  • TextfieldPassword
  • Thepiratebay
  • token
  • Torrentleech
  • Twitter
  • txtEmail
  • txtpass
  • txtPassword
  • txtuser
  • Uploaded
  • Uploading
  • userid
  • username
  • Vip-file
  • Webnames
  • Whatcd
  • Yahoo
  • YouPorn
  • YouTube

It attempts to steal user credentials used in the following websites:

  • 1and1
  • 4shared
  • Alertpay
  • Bcointernacional
  • BigString
  • Brazzers
  • Depositfiles
  • Dotster
  • DynDNS
  • Email
  • EmailName
  • FLN-Password
  • FLN-UserName
  • Facebook
  • Fastmail
  • Fileserve
  • Filesonic
  • Freakshare
  • Gmail
  • Godaddy
  • Hackforums
  • Hotfile
  • IKnowThatGirl
  • Letitbit
  • LogMeIn
  • Mediafire
  • Megaupload
  • Moneybookers
  • Moniker
  • Namecheap
  • Netflix
  • Netload
  • OfficeBanking
  • PayPal
  • Runescape
  • Sendspace
  • Sms4file
  • Speedyshare
  • Steam
  • TextfieldEmail
  • TextfieldPassword
  • Thepiratebay
  • Torrentleech
  • Twitter
  • Uploaded
  • Uploading
  • Vip-file
  • Webnames
  • Whatcd
  • Yahoo
  • YouPorn
  • YouTube

It hooks the following API to hide itself and to aid its routines:

  • CopyFileA
  • CopyFileW
  • CreateFileA
  • DeleteFileA
  • DeleteFileW
  • DnsFree
  • DnsQuery_A
  • DnsQuery_W
  • GetAddrInfoW
  • HttpSendRequestA
  • HttpSendRequestW
  • InternetWriteFile
  • MoveFileA
  • MoveFileW
  • NtEnumerateValueKey
  • NtQueryDirectoryFile
  • PR_Write
  • RegCreateKeyExA
  • RegCreateKeyExW
  • URLDownloadToFileA
  • URLDownloadToFileW

It monitors the following browsers:

  • chrome
  • firefox
  • flock
  • ieuser
  • iexplore
  • opera

It has the following backdoor capabilities:

  • Block DNS
  • Create processes
  • Download other files
  • Insert iframe tags into HTML files
  • Join an IRC channel
  • Log in to FTP sites
  • Modifies the following system files:
    • ipconfig.exe
    • verclsid.exe
    • regedit.exe
    • rundll32.exe
    • cmd.exe
    • regsvr32.exe
  • Perfrom Slowloris, UDP, and SYN flooding
  • Run Reverse Socks4 proxy server
  • Send MSN Messenger messages
  • Steal login credentials
  • Update itself
  • Visit a website

  SOLUTION

Minimum Scan Engine: 9.200

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

Scan your computer with your Trend Micro product and note files detected as WORM_DORKBOT.AZI

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

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\Run
    • {malware file name} = %System Root%\Documents and Settings\Administrator\Application Data\{malware file name}.exe

Step 5

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result. {drive letter}:\RECYCLER

Step 6

Search and delete these files

[ Learn More ]
There may be some component files 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. {drive letter}:\{folder name}.lnk

Step 7

Search and delete AUTORUN.INF files created by WORM_DORKBOT.AZI that contain these strings

[ Learn More ]
[AutoRun]
;{garbage characters}
shellexecute=RECYCLER\{malware file name}.exe
;{garbage characters}
icon=shell32.dll,7
;{garbage characters}
shell\open\command=RECYCLER\{malware file name}.exe
;{garbage characters}
action=Open folder to view files
;{garbage characters}
shell\explore\command=RECYCLER\{malware file name}.exe
;{garbage characters}
useautoplay=1

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_DORKBOT.AZI. 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 9

  1. Open a command prompt.
    • For Windows 2000, Windows XP, and Windows Server 2003 users, click Start>Run. In the Open input box, type CMD then press Enter.
  2. In the CMD console, type the following:

    ATTRIB [+R | -R] [+A | -A ] [+S | -S] [+H | -H] [+I | -I] [drive:][path][file name] [/S [/D] [/L]]

    Where:
    + Sets an attribute.
    - Clears an attribute
    R Read-only file attribute
    A Archive file attribute
    S System file attribute
    H Hidden file attribute
    I Not content indexed file attribute
    [drive:][path][filename]
    Specifies a file or files for attrib to process
    /S Processes matching files in the current folder and all subfolders.
    /D Processes folders
    /L Work on the attributes of the Symbolic Link versus the target of the Symbolic Link
    Example:
    To unhide all files and folders (including subfolders) in drive D:
    ATTRIB –H D:\* /S /D
  3. Repeat Step 2 for folders and files in other drives or directories.

Step 10

Scan your computer with your Trend Micro product to delete files detected as WORM_DORKBOT.AZI. 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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