Fwd: Virus Alert : Conti Ransomware

1 year ago 97

It has been reported that a new ransomware, named "Conti ransomware" is

spreading. In its infection stages, threat actors breach the corporate

networks and spread laterally to acquire domain administration privilege

for deploying ransomware. The coding pattern of Conti appears similar to

erstwhile "Ryuk ransomware" version 2 and ransomware note used is also same

as Ryuk had dropped in its earlier attacks. Moreover, the same TrickBot

infrastructure is utilized by both Ryuk and Conti threat actors as part

attacking mechanism. Conti is a human-operated ransomware designed to be

directly controlled by its operator rather than execute automatically by


Infection mechanism: 

When starts, Conti executes 146 commands focused on stopping potential

Windows services related to security, backup, database and email solutions.

Then it deletes the Volume Shadow Copies in a unique way and begins

encryption. The ransomware appends the .CONTI extension to encrypted files

and drop a ransom note named CONTI_README.txt in each folder.

When encrypting data, the ransomware uses a unique AES-256 encryption key

per file, which is then encrypted with a bundled RSA-4096 public encryption

key (unique per victim).

Conti ransomware is also special in its selection of encryption targets

that could be local hard drive or network shares, even specific, targeted,

IP addresses via a command-line client. It can be configured to skip

encrypting files on local drives and encrypt data on networked SMB shares.

This may lead to targeted damage and may cause destruction limited to

shares of a server that has no internet capability making it likely

unnoticeable for days or weeks. 

It also supports an "--encrypt_mode" argument to upgrade its encryption

strength. When using "-encrypt_mode local," only the local drives are

encrypted, and when using the "-encrypt_mode network," only the network

shares are encrypted. 

Another notable feature of Conti ransomware is that it utilizes a large no.

of concurrent CPU thread, namely 32 threads for encrypting different files

simultaneously with a very fast speed. However due to this, CPU and disk

utilization goes up causing of machine become sluggish and may serve as an

alarming situation for a user.

Another feature observed that its code abusing "Windows Restart Manager" -

the Windows component that unlocks files before performing an OS restart.

Conti utilizes this component to unlock and shut down app processes so it

can encrypt their respective data. This technique can be phenomenal on

Windows servers where sensitive data is usually managed by a database and

almost always up and running. 


Associated emails:



For Metadata for the Conti malware sample, AES-256 public key used for

encryption and another detailed IOC please refer the URL:

Countermeasures and Best practices for prevention:

Users are advised to disable their RDP if not in use, if required, it

should be placed behind the firewall and users are to bind with proper

policies while using the RDP.

All operating systems and applications should be kept updated on a regular

basis. Virtual patching can be considered for protecting legacy systems and

networks. This measure hinders cybercriminals from gaining easy access to

any system through vulnerabilities in outdated applications and software.

Avoid applying updates / patches available in any unofficial channel.

Restrict execution of Power shell /WSCRIPT in an enterprise environment.

Ensure installation and use of the latest version of PowerShell, with

enhanced logging enabled. Script block logging and transcription enabled.

Send the associated logs to a centralized log repository for monitoring and



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.

Application whitelisting/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.

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


Block the attachments of file types,


Consider encrypting the confidential data as the ransomware generally

targets common file types.

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


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.

Install ad blockers to combat exploit kits such as Fallout that are

distributed via malicious advertising.


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