Few Basics (a short video on
What is a Ransomware
a type of malicious software designed to block access to a computer system
until a sum of money is paid
Ransomware is a type of malware that can be covertly installed on a
computer without knowledge or intention of the user that restricts access to
the infected computer system in some way, and demands that the user pay
a ransom to the malware operators to remove the restriction.
The first known Ransomware was the 1989 “AIDS” Trojan (also
known as “PC Cyborg”) written by Joseph Popp
Extortionate ransomware became prominent in May 2005
By mid-2006, worms such as Gpcode, TROJ.RANSOM.A,
Archiveus, Cryzip and MayArchive began utilizing more
sophasticated RSA encryption schemes, with ever-increasing Key-
In 2011,a ransomware worm imitating the windows product
activation notice surfaced
In February 2013, a ransomware worm based off the Stamp.Ek
exploit kit surfaced
In July 2013, an OS X-specific ransomware worm came into action
Cryptolocker has raked in around 5 million dollars and still counting
since the end of 2013
Terminology and Propagation
The cryptovirology form of the attack has ransomware systematically
encrypt files on the system's hard drive, which becomes intractable to
decrypt without paying the ransom for the decryption key.
(Cryptovirology is a field that studies how to use cryptography to design
powerful malicious software.)
Other attacks may simply lock the system and display messages intended
to coax the user into paying.
Ransomware typically propagates as a Trojan, whose payload is disguised
as a seemingly legitimate file.
How Cyber criminals / Hackers install
Ransomware generates a pop-up window, webpage or email
warning from what looks like an official authority
Ransomware is usually installed when you open
- A malicious email attachment
- Click a malicious link in
1. an email message
2. an instant message
3. on social networking site
Ransomware can even be installed when you visit a
Types of Ransomware
Lock Screen Ransomware
Master Boot Record (MBR) Ransomware
Encrypts personal files/folders (e.g., the contents of
you‟re my documents folder-documents, spreadsheets,
Files are deleted once they are encrypted and
generally there is a text file in the same folder as the
now-inaccessible files with instructions for payment.
You may see a lock screen but not all variants show
Instead you may only notice a problem when you
attempt to open your files
This type is also called „file encryptor‟ ransomware
Lock Screen Ransomware
„Locks‟ the screen and demands payment
Presents a full screen image that blocks all the
This type is called „WinLocker‟ ransomware
No personal files are encrypted
Master Boot Record (MBR)
The master boot record (MBR) is a section of the
computer‟s hard drive that allows the operating system to
MBR ransomware changes the computer‟s MBR so the
normal boot process is interrupted
A ransom demand is displayed on screen instead
In 2012, a major ransomware worm known as Reveton began to spread.
It is also known as "police trojan".
Its payload displays a warning purportedly from a law enforcement agency.
claiming that the computer had been used for illegal activities, such as
downloading pirated software, promoting terrorism, copyright etc.
The warning informs the user that to unlock their system they would have to pay
To increase the illusion that the computer is being tracked by law enforcement,
the screen also displays the computer's IP address and footage from a
An Encrypting ransomware reappeared in 2013.
Distributed either as an attachment to a malicious e-mail or as a drive-by
encrypts certain types of files stored on local and mounted network drives
using RSA public-key cryptography.
The private key stored only on the malware's control servers.
Offers to decrypt the data if a payment (through either Bitcoin or a pre-paid
voucher) is made by a stated deadline.
threatens to delete the private key if the deadline passes.
If the deadline is not met, the malware offers to decrypt data via an online
service provided by the malware's operators, for a significantly higher price in
How to prevent ransomware ?
Keep all of the software on your computer up to date.
Make sure automatic updating is turned on to get all
the latest Microsoft security updates and browser-
related components (Java, Adobe, and the like).
Keep your firewall turned on.
Don't open spam email messages or click links on
suspicious websites. (CryptoLocker spreads via .zip
files sent as email attachments, for example.)
Download Microsoft Security Essentials, which is free, or use
another reputable antivirus and anti-malware program.
If you run Windows 8 or Windows RT, you don‟t need
Microsoft Security Essentials.
Scan your computer with the Microsoft Safety Scanner.
Keep your browser clean.
Always have a good backup system in place, just in case your
PC does become infected and you can‟t recover your files.
Identify The Ransomware
Most commonly, ransomware is saved to one of
the following locations:
C:Programdata(random alpha numerics).exe
Removal – Microsoft Procedure
The following Microsoft products can detect and remove this
Windows Defender (built into Windows 8)
Microsoft Security Essentials
Microsoft Safety Scanner
Windows Defender Offline (Some ransomware will not allow
you to use the products listed here, so you might have to start
your computer from a Windows Defender Offline disk.)
Removal – Other Anti-Malware
Start your computer in “Safe Mode with Networking”.
Stop and clean malicious running processes.
○ Download and save "RogueKiller" utility on your computer'*
(e.g. your Desktop).
○ Double Click to run RogueKiller.
○ Let the prescan to complete and then press on "Scan" button
to perform a full scan.
○ When the full scan is completed, press the "Delete" button to
remove all malicious items found.
○ Close RogueKiller and proceed to the next Step.
Clean Remaining Malicious Threats
Download and install a reliable FREE/Pro anti malware
programs to clean your computer from remaining malicious
threats. E.g. Malwarebytes Anti-Malware, Norton etc.
Run "Anti-Malware" and allow the program to update to it's latest
version and malicious database if needed.
let the program scan your system for threats.
Select all threats in result scan and remove all.
When the removal of infected objects process is complete,
“Restart your system to remove all active threats properly”.
Delete Cryptolocker Hidden Files
Enable the hidden files view from control panel.
Navigate to the following paths and delete all
Cryptolocker Hidden files:
For Windows XP
C:Documents and Settings<YOUR USERNAME>Application
For Windows Vista or Windows 7
Delete Temporary files
Finally delete all files and folders under your TEMP
For Windows Vista or Windows 7
For Windows XP
C:Documents and Settings<YOUR USERNAME>Local
File Restore- Shadow Copies
Navigate to the folder or the file that you want to restore in a
previous state and right-click on it.
From the drop-down menu select “Restore Previous Versions”. *
Notice* for Windows XP users: Select “Properties” and then the
“Previous Versions” tab.
Then choose a particular version of folder or file and the press the:
“Open” button to view the contents of that folder/file.
“Copy” to copy this folder/file to another location on your computer (e.g. you
external hard drive).
“Restore” to restore the folder file to the same location and replace the
Name- Trojan:W32/Reveton and Trojan:W32/Urausy
Boot the system into 'Safe Mode with Command
In the command prompt, type "regedit" and press
Look for the following registry values and remove
For Reveton, delete the "ctfmon.exe" registry value
For Urausy, delete the "shell" registry value from
ONLY IF these two conditions are met:
1. The "shell" registry value is located under HKEY_CURRENT_USER
and Not “ HKEY_LOCAL_MACHINE”.
WARNING! Deleting the "shell" value if it is listed under HKEY_LOCAL_MACHINE may break the Windows system.
2. There is a reference to a .dat file (e.g. skype.dat) in the value data.
Reboot the system again, this time into Normal mode.
Finally, run a full computer scan to repair any remaining
Backup and Recovery
Follow the principle of Least Privilege
(People / Software / Network)
When it comes to malware attacks, knowledge is
the best possible weapon to prevent them. Be
careful what you click!! Preventive measures
should be taken before ransomwares establish
strong hold. Keeping all the software updated and
getting latest security updates might help to
prevent the attacks. Use of antivirus and original
software is highly recommended. Creating
software restriction policy is the best tool to prevent
a Cryptolocker infection in the first place in
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