1. Symantec/
  2. Security Response/
  3. Trojan.Ransomlock.AI


Risk Level 1: Very Low

September 16, 2013
September 17, 2013 10:32:24 AM
Systems Affected:
The Trojan must be manually installed.

When the Trojan is executed, it creates the following file:

It then disables task switching and hides the taskbar.

Next, it creates the following registry entry so that it executes whenever Windows starts:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\"blue" = "\"%CurrentFolder%\[ORIGINAL FILE NAME].exe\""

The Trojan then creates the following registry entry to disable Task Manager:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System\"DisableTaskMgr" = "1"

The Trojan then hides the desktop and shows a fake blue screen asking the user to contact a specified QQ number to purchase a password.

Next, the Trojan asks the user to press the F10 key in order to enter the password and unlock the computer. All other keys may be disabled until the F10 key is pressed.

Computers compromised with Trojan.Ransomlock.AI can be unlocked using the following passwords:

Sample MD5: 4b6cbe978ab249a06a8ff5e5d9a0b778
Password: 4049133195201314

Sample MD5: 6c0039f4e354d78fb9fed032b9d95c62
Password: 5438

Sample MD5: 7272842f13f40a2d05669daae6b7732b
Password: 54sb+2b=hp

Sample MD5: 91a37b30dce6e41b96adaf30a939a500
Password: 610938

Sample MD5: b35361a2087268347c18b111ed749c00
Password: woshidashabi

Sample MD5: d61cf1670fd0ef41bf34cb4cc3ce5bff
Password: taizizhizuo

Sample MD5: e3baaec8269de4af3cd1f5746b9249e5
Password: feifei520

Sample MD5: f45199bfaaebe21528efaa7bc35c925e
Password: 895219272


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: Liang Yuan
Summary| Technical Details| Removal

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