Infostealer.Banker.C

It has been reported that this threat may arrive with a spoofed email, which pretends to be an update for customers sent by ABN-AMRO bank.

The e-mail is written in Dutch and has the following characteristics:

From:
support@abnamro.nl

Subject:
Vernieuw uw Internet-browser met SSL3 zo spoedig mogelijk.

Attachment:
ms_ssl3_upd.exe

When the Trojan is executed, it creates one of the following mutexes to ensure that only one copy of the threat is running on the computer:

• __SYSTEM__64AD0625__
• _AVIRA_21099

It checks for the presence of the following firewall programs:

• ZLCLIENT.EXE
• OUTPOST.EXE

It then gathers the following information from the compromised computer:

• OS version
• Presence of Service Pack 2
• Language of the system

Next, the Trojan copies itself to one of the following locations and appends a random amount of data to the file in order to have a random size:

• %System%\ntos.exe
• %System%\sdra64.exe

It creates one of the following folders with system and hidden attributes:

• %System%\wsnpoem
• %System%\lowsec

The Trojan may then create some of the following files, the first of which is used to save gathered information and the second is used to store the encrypted configuration of the Trojan:

• %System%\wsnpoem\audio.dll
• %System%\wsnpoem\video.dll
• %System%\lowsec\local.ds
• %System%\lowsec\user.ds

Next, the Trojan creates the following registry entries so that it executes whenever Windows starts:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\"userinit" = "%System%\ntos.exe"
HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Run\"userinit" = "%System%\ntos.exe"

It also modifies one of the following registry entries so that it executes whenever Windows starts:

• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\"Userinit" = "%System%\userinit.exe, %System%\ntos.exe"
• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\"Userinit" = "%System%\userinit.exe, %System%\sdra64.exe"

Next, it injects malicious code into the following running processes:

• WINLOGON.EXE
• SVCHOST.EXE
• EXPLORER.EXE
  

It attempts to create a malicious thread in all running processes except for the following one:
CSRSS.EXE

The Trojan creates some of the following mutexes to synchronize all active threads while running in memory:

• __SYSTEM__23D80F10__
• __SYSTEM__45A2F601__
• __SYSTEM__7F4523E5__
• __SYSTEM__91C38905__
• _AVIRA_2110
• _AVIRA_2101
• _AVIRA_2108
• _AVIRA_2109

The injected code will prevent the removal of the Trojan by blocking access and deletion of all of the malicious files and by regenerating all of the registry subkeys associated with the Trojan when they are deleted.

Next, it may add the following registry entries as infection markers for the compromised computer:

• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Network\"UID" = "[COMPUTERNAME]_[UNIQUE_ID]"
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\"{6780A29E-6A18-0C70-1DFF-1610DDE00108}" = "[HEXADECIMAL VALUE]"
• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\"{F710FA10-2031-3106-8872-93A2B5C5C620}" = "[HEXADECIMAL VALUE]"

The Trojan deletes cookies in the Internet Explorer URL cache so that users will have to re-insert passwords when logging into banking Web sites.

It reads PStore to steal saved passwords on the compromised computer.

It then hooks the following system functions of NTDLL.DLL using rootkit techniques to ensure that its code gets injected into each process:

• NtCreateThread
• LdrLoadDll
• LdrGetProcedureAddress

The Trojan attempts to hook the following functions in the WININET.DLL library to have control of network functionalities and to steal sensitive information:

• HttpSendRequestW
• HttpSendRequestA
• HttpSendRequestExW
• HttpSendRequestExA
• InternetReadFile
• InternetReadFileExW
• InternetReadFileExA
• InternetQueryDataAvailable
• InternetCloseHandle

It attempts to hook the following functions in the WS2_32.DLL and WSOCK32.DLL libraries to have control of network functionalities and to steal sensitive information:

• send
• sendto
• closesocket
• WSASend
• WSASendTo

It also attempts to hook the following functions in the USER32.DLL library to have control of network functionalities and to steal sensitive information:

• GetMessageW
• GetMessageA
• PeekMessageW
• PeekMessageA
• GetClipboardData

The Trojan may modify the content of the %System%\drivers\etc\hosts file.

The Trojan may perform the following actions:

• Intercept network traffic
• Intercept keyboard input
• Steal information from Windows clipboard
• Capture screenshots
• Redirect traffic

The Trojan is configured to search for specific keywords in URLs and also in HTTP packets. The default configuration includes the following strings to be searched, where asterisk (*) means a wild card:

• *Tan*
• *Schmetterling*
• *berweisung*
• *Amount*
• *tanentry*
• *RESULT2*
• *citibank.de/*
• I2=*&H0=DT
• *banking.*/cgi/ueber*.cgi*
• ###=######&tid=*
• [https://]onlineeast.bankofamerica.com/cgi-bin/ias/*/GotoW[REMOVED]
• CustomerServiceMenuEntryPoint?custAction=75
• bankofamerica.com/cgi-bin/ias/*/GotoWelcome
• *<input *value="
• *<option selected'
• *<select

It downloads an additional encrypted configuration file from one of the following URLs and saves it to %System%\video.dll:

• 81.95.148.244/911/cfg2.bin
• [http://]basdzsdas.com/poker/config.bin

At the time of writing, the decrypted configuration contains some the following strings to be searched by the Trojan:

• [https://]extranet.banesto.es/*/loginParti[REMOVED]
• [https://]banesnet.banesto.es/*/loginEmp[REMOVED]
• [https://]empresas.gruposantander.es/WebEmpresas/servlet/webempresa[REMOVED]
• [https://]banca.cajaen.es/Jaen/C@JAENdi[REMOVED]
• [https://]www.cajavital.es/Appserver/vita[REMOVED]
• [https://]www.cajalaboral.com*/home/acces[REMOVED]
• [https://]cipehb*.cdg.citibank.de/HomeBankingSecure/Pers/StartSes[REMOVED]

The Trojan may upload the gathered information to a remote site by using FTP protocol.