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Android.Skullkey

Android.Skullkey

Discovered:
July 23, 2013
Updated:
July 25, 2013
Infection Length:
Varies
Systems Affected:
Android
Android.Skullkey is a Trojan horse for Android devices that gives the attacker remote control of the compromised device to perform malicious activity.

Android package file
The Trojan must be manually downloaded and installed. It generally arrives within a repackaged .apk file from a legitimate application. The package name, publisher, and other details will vary and may be taken directly from the original application.

The Trojan may arrive as a package with the following characteristics:

Package names : com.hk515.doctor, com.hk515.activity

Malicious code is inserted in the package in the following locations:
  • com.google.safemain
  • com.google.service

Antivirus Protection Dates

  • Initial Rapid Release version July 23, 2013 revision 023
  • Latest Rapid Release version August 05, 2013 revision 033
  • Initial Daily Certified version July 23, 2013 revision 024
  • Latest Daily Certified version August 06, 2013 revision 002
  • Initial Weekly Certified release date July 24, 2013
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.
Android package file
The Trojan must be manually downloaded and installed. It generally arrives within a repackaged .apk file from a legitimate application. The package name, publisher, and other details will vary and may be taken directly from the original application.

The Trojan may arrive as a package with the following characteristics:

Package names : com.hk515.doctor, com.hk515.activity

Malicious code is inserted in the package in the following locations:
  • com.google.safemain
  • com.google.service

Permissions
When the Trojan is being installed, it requests permissions to perform the following additional actions:
  • Clear the caches of all installed applications on the device.
  • Read user's contacts data.
  • Monitor incoming SMS messages.
  • Read SMS messages on the device.
  • Send SMS messages.
  • Start once the device has finished booting.
  • Change the background wallpaper.
  • Monitor incoming WAP push messages.

Functionality

The Trojan hides using the Android 'Master Key' vulnerability to keep the legitimate app signature valid.

The Trojan allows attackers to perform the following actions:
  • Open a back door
  • Steal sensitive data (such as IMEI and phone number) and sends it to apkshopping.com
  • Send premium SMS messages
  • Disable certain security apps by using any available root commands

The Trojan will also send the following SMS message to all the device's contacts:


Note: The variable #name# is replaced with the recipient contact name and the URL is an inserted link obtained from andro1ds.com

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.
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 Google Play Store .

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. Select the Android icon to begin downloading the product.
  3. Select Install in order to accept the permissions that are being requested by the program.
  4. Next, select 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 select 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. Select 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, select Manage.
  4. Select the application and select Uninstall.
Writeup By: Joseph Bingham