Cryptowall Ransomware

First observed in 2014, Cryptowall is a ransomware trojan that has the capability to encrypt files on network and removable drives. Targets have primarily been in the USA and UK.

Threat ID:: CC-1959
Category:: Ransomware
Threat Severity:: Medium
Threat Vector:: Email spam, Drive by download
Published:: 25 January 2018 12:00 AM

Report a cyber attack: call 0300 303 5222 or email [email protected]

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Summary

First observed in 2014, Cryptowall is a ransomware trojan that has the capability to encrypt files on network and removable drives. Targets have primarily been in the USA and UK.

Affected platforms

The following platforms are known to be affected:

Microsoft Windows

Microsoft Windows - All versions

Threat details

Cryptowall has been distributed by a wide variety of means including malicious email attachments, exploit kits, drive-by downloads and malicious adverts. Additionally, it is often installed by other malware.

When installed, Cryptowall creates a malicious instance of Windows Explorer. It then deletes all Shadow Copies of the file system and disables the System Restore feature, to prevent recovery. It copies itself into several locations and creates several registry entries, so that it runs every time the computer restarts.

It then communicates with its command and control (C2) server during the encryption process. Encryption uses the RSA algorithm with a strong 2048-bit key. When finished, a ransom demand is displayed to the user for the return of their data.

Remediation advice

To avoid becoming infected with ransomware, ensure that:

Remediation steps

Type	Step
	A robust program of education and awareness training is delivered to users to ensure they don’t open attachments or follow links within unsolicited emails. All operating systems, antivirus and other security products are kept up to date. All day to day computer activities such as email and internet are performed using non-administrative accounts and that permissions are always assigned on the basis of least privilege. Your organisation adopts a holistic all-round approach to Cyber Security as advocated by the “10 Steps to Cyber Security”. To limit the damage of ransomware and enable recovery: All critical data must be backed up, and these backups must be sufficiently protected/kept out of reach of ransomware. Multiple backups should be created including at least one off-network backup (e.g. to tape).

Type

Step

A robust program of education and awareness training is delivered to users to ensure they don’t open attachments or follow links within unsolicited emails.
All operating systems, antivirus and other security products are kept up to date.
All day to day computer activities such as email and internet are performed using non-administrative accounts and that permissions are always assigned on the basis of least privilege.
Your organisation adopts a holistic all-round approach to Cyber Security as advocated by the “10 Steps to Cyber Security”.

To limit the damage of ransomware and enable recovery:

All critical data must be backed up, and these backups must be sufficiently protected/kept out of reach of ransomware.

Multiple backups should be created including at least one off-network backup (e.g. to tape).

Last edited: 17 February 2020 12:41 pm