Threat behavior
TrojanSpy:Win32/Bancos.TA is a data-stealing trojan that captures online banking credentials, such as account login names and passwords, then relays the captured information to a remote attacker. Win32/Bancos.TA targets customers of the Brazilian bank "Banco Bradesco".
Installation
When run, TrojanSpy:Win32/Bancos.TA creates copies of itself as "%Appdata%\spoolsv.exe" and "%Temp%\services". It ensures that its copy automatically runs every time Windows starts by creating the following registry entry:
Adds value: "MicrosoftWinUpdate"
With data: "%Appdata%\spoolsv.exe"
To subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Payload
Steals user data
TrojanSpy:Win32/Bancos.TA monitors the computer to see if the user visits the following Web site:
This is the online banking Web site for the bank "Banco Bradesco". If this site is visited, TrojanSpy:Win32/Bancos.TA modifies the contents of the Web page as it is loaded by injecting code that can capture sensitive user details, such as user names and passwords for the site.
The captured details are sent to a remote attacker at "avsnew.zxq.net" using HTTP POST.
Downloads arbitrary files
TrojanSpy:Win32/Bancos.TA can download arbitrary files from the Web site "greatisweb.com". These files may be detected as other malware.
Analysis by Marian Radu
Prevention
