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PREVENTION OF RANSOMWARE INFECTIONS

ORIGINAL ISSUE DATE:-NOVEMBER 17, 2016

VIRUS TYPE:- RANSOMWARE



It has been observed that "Ransomware malware" attacks are on rise affecting
financial institutions, businesses and academic institutions in the country.
Ransomware are type of malicious software (malware) that scramble the contents
of a computer or server (associated network shares and removable media) and
demands payment/ransom to unlock it, usually in the form of anonymous
decentralized virtual currency "BITCOINS".
Ransomware causes temporary or permanent loss of sensitive or proprietary
information, financial losses, and disruption to regular operations and
potential harm to an organization's reputation. This Advisory is intended to
provide further information about Ransomware, its main characteristics, the
proliferation mechanisms and to provide prevention or mitigation measures
against ransomware.





Modus Operandi of Ransomware Attacks
Infection/Propagation

Ransomware is typically spread through spear phishing emails that contain
malicious attachments in the form of archived content (zip/rar) containing a
JavaScript file. Other possible infection vectors includes drive-by-download
attacks, specially crafted web links in emails. Upon visiting such
infected/compromised websites or web links, a piece of malware is dropped on
victim's machine, which executes itself without user's knowledge. It has also
been reported that the ransomware propagates through insecure Remote Desktop
connections (RDP). Ransomware attempts to extort money from victims by
displaying an extortion alert indicating that their computer has been locked or
all files have been encrypted, and demand that a ransom is paid to restore
access.



Impact

Ransomware variants are capable of performing following activities:

 * Encrypt the specific files present on the infected system, the encryption and
   the targeted file types varies by ransomware versions, hence make files
   unusable.
 * Capable of infecting or encrypting the files present on network share drives
   and USB drives.
 * Extensions of the unusable /encrypted files depends upon the type of the
   ransomware, such as ".cerber", ".crypt", ".zepto", ".locky" , ".xtbl",
   ".vault", "xrtn", "crySIS", ".lock", ".R5A". ".lock", etc.
 * Make use of native Windows utilities such as WMIC and/or VSSAdmin to delete
   backups and shadow copies.
 * Demands ransom amount of money for providing the decryption key for the
   encrypted files.
 * Some versions of the ransomware are capable of targeting the databases also
   by identifying the current running processes and if found any, they kill
   those processes and thereafter encrypts the database.
 * Capable of detecting the virtual machine environments by checking the VM
   specific file names , paths, hooked modules, known sandbox volume serial
   numbers, and VM specific DLLs.
 * Make network connections to the call back server to send uniquely
   identifiable system information.
 * Make file system and registry changes such as installation of specific
   windows themes representing ransomware encryption.
 * Capable of keeping persistence by creating command processor, screensaver,
   startup.run and Run Once registry entries.

Paying the ransom does not guarantee that the encrypted files will be released.
In addition, decrypting files does not mean the malware infection itself has
been removed. It has also been reported that attackers have gone one level
deeper by typically targeting the backend databases / backup which stores
critical financial data. In contrast with the conventional ransomware
methodology, wherein "IN-ONE-GO" encryption of the files /documents is carried
out, in the latest attacks, attacker tampers specific fields /records of
databases which are sensitive in nature and subsequently demand ransom, an
indication of persistent access to the critical assets of an enterprise network.



Variants

Some of the well-known ransomwares that are spreading widely are:

Cryptolocker, locky, cerber, zepto, .CryptoHasYou., 7ev3n, Alpha Ransomware,
AutoLocky, BandarChor, BitCrypt, Booyah, Brazillian, Chimera, Crybola, Cryptear,
CryptFile2, CryptInfinite, CryptoDefense, CryptoHost, CryptoJoker, CryptoMix,
CryptoTorLocker, CryptoWall, CryptoXXXC2.0, CTB-Locker, CTB-Locker WEB,
DeCryptProtect, DMALocker, Gopher, HydraCrypt, Jigsaw, KeRanger, KEYBTC,
KEYHolder, KryptoLocker, Linux.Encoder, Locker, Lortok, NanoLocker, Nemucod,
Offline Ransomware, OMG!Ransomware, Operation Global3, PClock, Petya,
PornoLocker, PowerWare, Radamant, Rakhni, Ranmoh, Ransom32, Rector, EmindMe,
Rokku, scraper, SkidLocker /Pompous, SynoLocker, TeslaCrypt, TorrentLocker,
Troldesh, TrueCrypter, UmbreCrypt, VaultCrypt, Virus-Encoder.



Cyber security companies are working on decryption tools for such encrypted
files, but, till date decryption for only some of the ransomwares are possible.
For those files for which the decryption tools are not available, there is no
way to retrieve the private key that can be used to decrypt those files. Brute
forcing the decryption key is not realistic due to the length of time required
to break this type of cryptography. Restoring to earlier operating system state
may fail as the malware may delete the volume shadow copies (restore points in
windows) as the first step immediately after infection.

Some of the prevalent ransomware variants observed in Indian cyberspace are
CryptoLocker, Reveton, CTB-Locker, Cryptowall, Cerber, TeslaCrypt. Ransomwareare
evolving in their methods of propagation, encryption, and the targets sought.

CERT-In has issued alerts on ransomware such as Cryptolocker, Locky, Cerberetc.
The same may be seen on CERT-In website www.cert-in.org.in





Best Practices and remedial measures

Users and administrators are advised to take the following preventive measures
to protect their computer networks from ransomware infection/ 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.
 * Check regularly for the integrity of the information stored in the databases.
 * Regularly check the contents of backup files of databases for any
   unauthorized encrypted contents of data records or external elements,
   (backdoors /malicious scripts.)
 * Ensure integrity of the codes /scripts being used in database, authentication
   and sensitive systems
 * Establish a Sender Policy Framework (SPF) 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.
 * Keep the operating system third party applications (MS office, browsers,
   browser Plugins) up-to-date with the latest patches.
 * Application white listing/Strict implementation of Software Restriction
   Policies (SRP)to block binaries running from %APPDATA% and %TEMP% paths.
   Ransomware sample drops and executes generally from these locations.
 * Maintain updated Antivirus software on all systems
 * 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
 * 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 ActiveX content in Microsoft Office applications such as Word, Excel,
   etc.
 * Disable remote Desktop Connections, employ least-privileged accounts. Limit
   users who can log in using Remote Desktop, set an account lockout policy.
   Ensure proper RDP logging and configuration.
 * Restrict access using firewalls and allow only to selected remote endpoints,
   VPN may also be used with dedicated pool for RDP access
 * Use strong authentication protocol, such as Network Level Authentication
   (NLA) in Windows.
 * Additional Security measures that may be considered are
    * Use RDP Gateways for better management
    * Change the listening port for Remote Desktop
    * Tunnel Remote Desktop connections through IPSec or SSH
    * Two-factor authentication may also be considered for highly critical
      systems

 * If not required consider disabling, PowerShell / windows script hosting.
 * 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.
 * 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
 * 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



Prevention Tools:

 * Tool (NoMoreCry) to prevent Wannacry Ransomware by CCN-CERT:
   https://loreto.ccn-cert.cni.es/index.php/s/tYxMah1T7x7FhND?path=CCN-CERT%20NoMoreCry%20Tool
 * Sophos: Hitman.Pro
   https://www.hitmanpro.com/en-us/surfright/alert.aspx
 * Bitdefender Anti-Crypto Vaccine and Anti-Ransomware (discontinued)
   https://labs.bitdefender.com/2016/03/combination-crypto-ransomware-vaccine-released/
 * Malwarebytes Anti-Ransomware(formally Crypto Monitor)
   https://blog.malwarebytes.com/malwarebytes-news/2016/01/introducing-the-malwarebytes-anti-ransomware-beta/
 * Trendmicro Ransomware Screen Unlocker tool:
   https://esupport.trendmicro.com/en-us/home/pages/technical-support/1105975.aspx
 * Microsoft  Enhanced mitigation and experience toolkit(EMET)
   https://www.microsoft.com/en-us/download/details.aspx?id=50766



Removal Tools:

Download Free Bot Removal Tool





Decryption Methodology and Tools:

Decryption tools for some of the ransomware are available which allows users to
decrypt their unusable/encrypted files without paying ransom. Not all tools are
capable to decrypt the files, instead users are advised to try the below
mentioned decryption tools.




List of decryption tools are mentioned below:

 * http://www.avg.com/in-en/ransomware-decryption-tools
 * https://noransom.kaspersky.com/
 * https://success.trendmicro.com/solution/1114221-downloading-and-using-the-trend-micro-ransomware-file-decryptor
 * http://www.mcafee.com/in/downloads/free-tools/shadedecrypt.aspx
 * http://www.mcafee.com/in/downloads/free-tools/wildfiredecrypt.aspx
 * https://decrypter.emsisoft.com/
   
   

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References

 * https://www.europol.europa.eu/newsroom/news/just-released-fourth-decryption-tool-neutralises-latest-version-of-gandcrab-ransomware
 * http://www.kaspersky.com/au/about/news/virus/2014/Kaspersky-Lab-detects-mobile-Trojan-Svpeng-Financial-malware-with-ransomware-capabilities-now-targeting-US-users
 * https://www.symantec.com/connect/blogs/cryptodefense-cryptolocker-imitator-makes-over-34000-one-month
 * https://success.trendmicro.com/solution/1099423-best-practices-in-preventing-ransomware-infection-using-officescan-osce-and-worry-free-business-se#collapseTwo
 * https://nakedsecurity.sophos.com/2014/06/18/whats-next-for-ransomware-cryptowall-picks-up-where-cryptolocker-left-off/
 * https://www.symantec.com/connect/blogs/international-takedown-wounds-gameover-zeus-cybercrime-network
 * https://kc.mcafee.com/resources/sites/MCAFEE/content/live/PRODUCT_DOCUMENTATION/26000/PD26383/en_US/McAfee_Labs_Threat_Advisory-Ransomware-Locky.pdf
 * https://securingtomorrow.mcafee.com/mcafee-labs/cerber-ransomware-updates-configuration-file/
 * https://securingtomorrow.mcafee.com/mcafee-labs/cerber-ransomware-now-hunts-databases/
 * https://www.microsoft.com/en-us/security/portal/mmpc/shared/ransomware.aspx
 * http://www.cyberswachhtakendra.gov.in/alerts/wannacry_ransomware.html
 * http://www.cyberswachhtakendra.gov.in/alerts/petya_ransomware.html


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POSTAL ADDRESS:



Indian Computer Emergency Response Team (CERT-In)
Ministry of Electronics and Information Technology, Government of India,
Electronics Niketan, 6 CGO Complex,
Lodhi Road, New Delhi - 110 003
Toll Free Phone: +91-1800-11-4949
Toll Free Fax: +91-1800-11-6969

Disclaimer :- The information provided herein is on "as is" basis, without
warranty of any kind.

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