Threat Descriptions

Trojan-Dropper:OSX/Revir.A

Classification

Category :

Malware

Type :

Trojan-Dropper

Platform :

OSX

Aliases :

Trojan-Dropper:OSX/Revir.A, Trojan-Dropper:OSX/Revir.A

Summary

Trojan-Dropper:OSX/Revir.A drops a downloader component that downloads a backdoor program onto the system, while camouflaging its activity by opening a PDF file to distract the user.

Removal

The F-Secure security product will automatically remove the file.

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-Dropper:OSX/Revir.A drops a PDF file in the /tmp folder, then opens it to distract the user from noticing any other activity occuring:

Screenshot of a PDF file dropped by Trojan-Dropper:OSX/Revir.A.

The PDF file contains Chinese-language text related to political issues, which some users may find offensive.

Note that the PDF file in the screenshot above uses the name 'trojan.pdf'. The PDF file will actually use the same name as the trojan-dropper's binary file, which is usually saved to the /Users/%user%/Downloads or /User/%user%/Documents folders.

Activity

In the background, the malware will drop and execute the following downloader component (detected as Trojan-Downloader:OSX/Revir.A):

  • /tmp/host

This file downloads and executes a file from the following remote location:

  • h t t p://tarmu.narod.ru/[...]

The downloaded file is also saved as:

  • /tmp/updtdata

As of this writing, the downloaded file is detected as Backdoor:OSX/Imuler.A. Our Browsing Protection blocks the download server hosting the file.