Trojan:SymbOS/ZeusMitmo.A

Classification

Category :

Malware

Type :

Trojan

Platform :

SymbOS

Aliases :

Trojan:SymbOS/ZeusMitmo.A, Trojan:SymbOS/ZeusMitmo.A

Summary

When installed on a mobile phone, this trojan monitors all incoming SMS messages and acts as a backdoor for receiving commands sent by an attacker via SMS messages.

Removal

Trojan:SymbOS/ZeusMitmo can be manually uninstalled by removing the following program via the phone's Application Manager:

  • Nokia Update

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note: You need administrative rights to change the settings.

Technical Details

Trojan:SymbOS/ZeusMitmo.A is notable for being specifically designed to steal SMS messages containingm obile transaction authentication number (mTANs), which are like single-use passwords sent by banks to to their account holders' mobile phones to verify online transactions.

This trojan is discussed in the following Labs Weblog post:

Distribution

ZeusMitmo.A is distributed by Trojan-Spy:W32/Zbot.PUA or Trojan-Spy:W32/Zbot.PUB.

Trojan-Spy:W32/Zbot.PUA sends an SMS message to the user's phone containing a link to a website hosting the malicious ZeusMitmo trojan. If the link is followed, the trojan is promptly downloaded and installed on the phone.

In our analysis, the malicious trojan was a Symbian-signed file for S60 3rd Edition and 5th Edition mobile phones. The file itself is named cert.sis, and may be deceptively billed as a 'Nokia Update'. .jad files, used for Blackberry devices, have also been reported.

Installation

During installation, the trojan registers itself to start when the phone is booted up. Once active, the trojan is able to silently monitor all incoming SMS messages.

Activity

If an SMS is sent to the user's mobile device with the target bank's authentication code, the malicious software running in the device forwards the SMS to another terminal controlled by the attacker.

The trojan contains a hard-coded phone number for use in sending the stolen SMS messages and receiving commands from the attacker(s).