CryCryptor Ransomware

CryCryptor is ransomware that targets Android devices and is disguised as a COVID-19 tracing app. It is based on open-source ransomware called CryDroid that was found published on GitHub, ostensibly for 'research purposes'.

Threat ID:: CC-3523
Category:: Ransomware
Threat Severity:: Low
Threat Vector:: Download
Published:: 25 June 2020 12:00 AM

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

Summary

Affected platforms

The following platforms are known to be affected:

Android

Google Android - All versions, where not restricted to running Google Play Store apps only

Threat details

CryCryptor is distributed via websites that spoof health organisations. At the time of publication these websites have affected the Canadian health service. CryCryptor cannot be obtained from the Google Play store, so devices restricted to only running apps from the store are not affected.

When CryCryptor is run it encrypts common file types and saves a ransom note to every directory where files have been encrypted. Encrypted files have the extension '.enc' appended to the filenames. Additional files are saved containing the salt values used in each encryption and an initialisation vector. These files have the extensions '.enc.salt' and '.enc.iv' respectively.

When files have been encrypted, a notification is displayed directing users to open the ransom note.

Remediation steps

Type	Step
	A third-party decryption tool has been developed to recover file encrypted by CryCryptor. Please note that NHS Digital have not tested this tool and organisations use it at their own risk. If a device on your network becomes infected with ransomware it will begin encrypting files, which may also include remote files on network locations. The only guaranteed way to recover from a ransomware infection is to restore all affected files from their most recent backup. To reduce the likelihood of infection by ransomware, NHS Digital advises that: Secure configurations are applied to all devices. Security updates are applied at the earliest opportunity. Tamper protection settings in security products are enabled where available. Obsolete platforms are segregated from the rest of the network. IT usage policies are reinforced by regular training to ensure all users know not to open unsolicited links or attachments. Multi-factor authentication (MFA) and lockout policies are used where practicable, especially for administrative accounts. Administrative accounts are only used for necessary purposes. Remote administration services use strongly encrypted protocols and only accept connections from authorised users or locations. Systems are continuously monitored, and unusual activity is investigated, so that a compromise of the network can be detected as early as possible. Please note that NCSC maintains guidance for securely configuring a wide range of end user device (EUD) platforms. For further details refer to their end user device security guidance pages. To limit the impact of a ransomware infection, NHS Digital advises that: Critical data is frequently saved in multiple backup locations. At least one backup is kept offline at any time (separated from live systems). Backups and incident recovery plans are tested to ensure that data can be restored when needed. User account permissions for modifying data are regularly reviewed and restricted to the minimum necessary. Infected systems are disconnected from the network and powered down as soon as practicable. Any user account credentials that may have been compromised should be reset on a clean device. Where infected systems cannot be quarantined with confidence, then an affected organisation should disconnect from national networks to limit propagation.

Type

Step

A third-party decryption tool has been developed to recover file encrypted by CryCryptor. Please note that NHS Digital have not tested this tool and organisations use it at their own risk.

If a device on your network becomes infected with ransomware it will begin encrypting files, which may also include remote files on network locations. The only guaranteed way to recover from a ransomware infection is to restore all affected files from their most recent backup.

To reduce the likelihood of infection by ransomware, NHS Digital advises that:

Secure configurations are applied to all devices.
Security updates are applied at the earliest opportunity.
Tamper protection settings in security products are enabled where available.
Obsolete platforms are segregated from the rest of the network.
IT usage policies are reinforced by regular training to ensure all users know not to open unsolicited links or attachments.
Multi-factor authentication (MFA) and lockout policies are used where practicable, especially for administrative accounts.
Administrative accounts are only used for necessary purposes.
Remote administration services use strongly encrypted protocols and only accept connections from authorised users or locations.
Systems are continuously monitored, and unusual activity is investigated, so that a compromise of the network can be detected as early as possible.

Please note that NCSC maintains guidance for securely configuring a wide range of end user device (EUD) platforms. For further details refer to their end user device security guidance pages.

To limit the impact of a ransomware infection, NHS Digital advises that:

Critical data is frequently saved in multiple backup locations.
At least one backup is kept offline at any time (separated from live systems).
Backups and incident recovery plans are tested to ensure that data can be restored when needed.
User account permissions for modifying data are regularly reviewed and restricted to the minimum necessary.
Infected systems are disconnected from the network and powered down as soon as practicable.
Any user account credentials that may have been compromised should be reset on a clean device.
Where infected systems cannot be quarantined with confidence, then an affected organisation should disconnect from national networks to limit propagation.

Indicators of compromise

Main indicators

Domains

covid19tracer[.]ca
tracershield[.]ca

Android package name/hash (SHA-1)

com.crydroid
322AAB72228B1A9C179696E600C1AF335B376655

Ransom note

readme_now.txt

Last edited: 29 June 2021 12:01 pm