Android.Answerbot

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Discovered: October 07, 2011
Updated: October 07, 2011 11:27:25 AM
Type: Trojan
Systems Affected: Android

Android.Answerbot is a Trojan horse that opens a back door on Android devices.

Android Package File
The initial downloaded APK can vary as it will be named according to the legitimate application it is imitating.

The Trojan may also arrive as the following APK file:
[SINGLE CHARACTER].apk

Note: The file name changes as the version of the threat is updated, for example:

  • a.apk
  • b.apk
  • etc.


Installation
This threat must be manually installed. It is known to be distributed through Chinese third-party Android markets by re-packaging legitimate applications with the Trojan code.


Antivirus Protection Dates

  • Initial Rapid Release version October 07, 2011 revision 006
  • Latest Rapid Release version September 22, 2016 revision 024
  • Initial Daily Certified version October 07, 2011 revision 008
  • Latest Daily Certified version September 22, 2016 revision 025
  • Initial Weekly Certified release date October 12, 2011

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Poul Jensen

Discovered: October 07, 2011
Updated: October 07, 2011 11:27:25 AM
Type: Trojan
Systems Affected: Android

Android Package File
The initial downloaded APK can vary as it will be named according to the legitimate application it is imitating.

The Trojan may also arrive as the following APK file:
[SINGLE CHARACTER].apk

Note: The file name changes as the version of the threat is updated, for example:

  • a.apk
  • b.apk
  • etc.


Permissions
When installing the Trojan, it will ask for one or more of the following permissions:
  • Access information about networks
  • Allow access to low-level system logs
  • Allow applications to disable the keyguard
  • Allow applications to write the apn settings
  • Check the phone's current state
  • Create new contact data
  • Create new SMS messages
  • Initiate a phone call without using the Phone UI or requiring confirmation from the user
  • Make the phone vibrate
  • Monitor incoming SMS messages
  • Open network connections
  • Prevent processor for sleeping or screen from dimming
  • Read contact data
  • Read SMS messages on the device
  • Send SMS messages
  • Start once the device has finished booting


Installation
This threat must be manually installed. It is known to be distributed through Chinese third-party Android markets by repackaging legitimate applications with the Trojan code.





Information theft

The Trojan may steal personal information from the device and upload it to a remote location.


Functionality
When the Trojan is installed, it attempts to connect to a command and control (C&C) server with a URL in the following format:
http://blog.sina.com.cn/s/blog_[REMOVED].html

The above URL contains an encoded text string that, when decrypted, is a .zip or .apk package that the Trojan installs on the device. The package is used to update the functionality of the Trojan.

Note: blog.sina.com.cn is a legitimate blog hosting website. Their service is being abused by the attacker to host the malicious updates.

The Trojan then receives commands to download more malware on to the device.

It may then send SMS messages to premium numbers.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.

Writeup By: Poul Jensen

Discovered: October 07, 2011
Updated: October 07, 2011 11:27:25 AM
Type: Trojan
Systems Affected: Android

You may have arrived at this page either because you have been alerted by your Symantec product about this risk, or you are concerned that your device has been affected by this risk.


Install Norton Mobile Security
If you do not already have Norton Mobile Security installed on your device, please download the product from the Android marketplace .

Alternatively, you can navigate to the norton.mobi website from your device and download the product from there by completing the following steps:

  1. Select the 90-Day free download.
  2. Click on the Android icon to begin downloading the product.
  3. Click on Install in order to accept the permissions that are being requested by the program.
  4. Next, click Open and then Agree & Launch.

Note: The first time the product runs, you will be required to enter a code that is displayed on the screen in order to activate the product. Enter the provided code and press Submit .


Run a full system scan
Run a full system scan using Norton Mobile Security to remove this risk from the device. To do this, please perform the following actions:
  1. Navigate to the Anti-Malware tab.
  2. Click Scan Now.


Manual removal
To remove this risk manually, please perform the following actions:
  1. Open the Google Android Menu.
  2. Go to the Settings icon and select Applications.
  3. Next, click Manage.
  4. Select the application and click the Uninstall button.

Writeup By: Poul Jensen