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Understanding Ransomware

What is ransomware?

Ransomware is a type of malware that can stop you from using your PC, or encrypt your files so you can’t use them. You may be warned that you need to pay money, complete surveys, or perform other actions before you can use your PC again.

Ransomware can get on your PC from nearly any source that any other malware (including viruses) can come from. This includes:

  • Visiting unsafe, suspicious, or fake websites.
  • Opening emails and email attachments from people you don’t know, or that you weren’t expecting.
  • Clicking on malicious or bad links in emails, social media posts, instant messenger chats, etc.

What does ransomware do?

There are different types of ransomware - lockscreen ransomware and encryption ransomware.

Lockscreen ransomware shows a full-screen message that prevents you from accessing your PC or files. It says you have to pay money (a "ransom") to get access to your PC again.

Encryption ransomware changes your files so you can’t open them. It does this by encrypting the files.

However, all of them will prevent you from using your PC normally, and they will all ask you to do something before you can use your PC. They can target any PC users, whether it’s a home computer, endpoints in an enterprise network, or servers used by a government agency or healthcare provider. Ransomware can:

  • Prevent you from accessing your software.
  • Encrypt files so you can't use them.
  • Stop certain apps from running (like your web browser).

Ransomware will demand that you pay money (a “ransom”) to get access to your PC or files. Some may also make you complete surveys. There is no guarantee that paying the fine or doing what the ransomware tells you will give access to your PC or files again.

Source : Microsoft Malware Protection Center.

Recent ransomware attacks

During May 2017, it has been reported that a ransomware named as "Wannacry" is spreading widely. Wannacry encrypts the files on infected Windows systems. This ransomware spreads by using a vulnerability in implementations of Server Message Block (SMB) in Windows systems. This exploit is named as ETERNALBLUE.

The ransomware called WannaCrypt or WannaCry encrypts the computer's hard disk drive and then spreads laterally between computers on the same LAN. The ransomware also spreads through malicious attachments to emails.

Indian Computer Emergency Response Team (CERT-In) has issued a critical alert in this regard. To access the same, click here..

Best practices to prevent ransomware attacks

  • Perform regular backups of all critical information to limit the impact of data or system loss and to help expedite the recovery process. Ideally, this data should be kept on a separate device, and backups should be stored offline.
  • Establish a Sender Policy Framework (SPF), Domain Message Authentication Reporting and Conformance (DMARC), and Domain Keys Identified Mail (DKIM) for your domain, which is an email validation system designed to prevent spam by detecting email spoofing by which most of the ransomware samples successfully reaches the corporate email boxes.
  • Don't open attachments in unsolicited e-mails, even if they come from people in your contact list, and never click on a URL contained in an unsolicited e-mail, even if the link seems benign. In cases of genuine URLs close out the e-mail and go to the organization's website directly through browser
  • Restrict execution of powershell /WSCRIPT in enterprise environment Ensure installation and use of the latest version (currently v5.0) of PowerShell, with enhanced logging enabled. script block logging, and transcription enabled. Send the associated logs to a centralized log repository for monitoring and analysis.
  • Application whitelisting/Strict implementation of Software Restriction Policies (SRP) to block binaries running from %APPDATA%, %PROGRAMDATA% and %TEMP% paths. Ransomware sample drops and executes generally from these locations. Enforce application whitelisting on all endpoint workstations.
  • Deploy web and email filters on the network. Configure these devices to scan for known bad domains, sources, and addresses; block these before receiving and downloading messages. Scan all emails, attachments, and downloads both on the host and at the mail gateway with a reputable antivirus solution.
  • Disable macros in Microsoft Office products. Some Office products allow for the disabling of macros that originate from outside of an organization and can provide a hybrid approach when the organization depends on the legitimate use of macros. For Windows, specific settings can block macros originating from the Internet from running.
  • Configure access controls including file, directory, and network share permissions with least privilege in mind. If a user only needs to read specific files, they should not have write access to those files, directories, or shares.
  • Maintain updated Antivirus software on all systems
  • Consider installing Enhanced Mitigation Experience Toolkit, or similar host-level anti-exploitation tools.
  • Block the attachments of file types - exe, pif, tmp, url, vb, vbe, scr, reg, cer, pst, cmd, com, bat, dll, dat, hlp, hta, js, wsf.
  • Regularly check the contents of backup files of databases for any unauthorized encrypted contents of data records or external elements, (backdoors /malicious scripts.)
  • Keep the operating system third party applications (MS office, browsers, browser Plugins) up-to-date with the latest patches.
  • Follow safe practices when browsing the web. Ensure the web browsers are secured enough with appropriate content controls.
  • Network segmentation and segregation into security zones - help protect sensitive information and critical services. Separate administrative network from business processes with physical controls and Virtual Local Area Networks.
  • Disable remote Desktop Connections, employ least-privileged accounts.
  • Ensure integrity of the codes /scripts being used in database, authentication and sensitive systems, Check regularly for the integrity of the information stored in the databases.
  • Restrict users' abilities (permissions) to install and run unwanted software applications.
  • Enable personal firewalls on workstations.
  • Implement strict External Device (USB drive) usage policy.
  • Employ data-at-rest and data-in-transit encryption.
  • Carry out vulnerability Assessment and Penetration Testing (VAPT) and information security audit of critical networks/systems, especially database servers from CERT-IN empaneled auditors. Repeat audits at regular intervals.
  • Individuals or organizations are not encouraged to pay the ransom, as this does not guarantee files will be released. Report such instances of fraud to CERT-In and Law Enforcement agencies.

Source : Cyber Swachhta Kendra.



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