Cyber Threat Report: 'From OneNote to RansomNote: An Ice Cold Intrusion'

This case report from The DFIR Report describes an intrusion which started with a malicious OneNote attachment. Opening the OneNote file led to the download of an IcedID DLL from a remote server. Following discovery activities, on day 33 of the intrusion IcedID was used to launch multiple CobaltStrike beacons. The threat actor installed AnyDesk for additional remote access and then utilised FileZilla to exfiltrate data. Finally the actor deployed a variant of the Nokoyawa ransomware to encrypt data.

Encrypt Sensitive Information

Protect sensitive information with strong encryption.

Restrict File and Directory Permissions

Restrict access by setting directory and file permissions that are not specific to users or privileged accounts.

Remote Data Storage

Use remote security log and sensitive file storage where access can be controlled better to prevent exposure of intrusion detection log data or sensitive information.

Network Intrusion Prevention

Use intrusion detection signatures to block traffic at network boundaries.

Filter Network Traffic

Use network appliances to filter ingress or egress traffic and perform protocol-based filtering. Configure software on endpoints to filter network traffic.

User Account Management

Manage the creation, modification, use, and permissions associated to user accounts.

Data Loss Prevention

Use a data loss prevention (DLP) strategy to categorize sensitive data, identify data formats indicative of personal identifiable information (PII), and restrict exfiltration of sensitive data.(Citation: PurpleSec Data Loss Prevention)

Network Segmentation

Architect sections of the network to isolate critical systems, functions, or resources. Use physical and logical segmentation to prevent access to potentially sensitive systems and information. Use a DMZ to contain any internet-facing services...

Disable or Remove Feature or Program

Remove or deny access to unnecessary and potentially vulnerable software to prevent abuse by adversaries.

Privileged Account Management

Manage the creation, modification, use, and permissions associated to privileged accounts, including SYSTEM and root.

Execution Prevention

Block execution of code on a system through application control, and/or script blocking.

Code Signing

Enforce binary and application integrity with digital signature verification to prevent untrusted code from executing.

Antivirus/Antimalware

Use signatures or heuristics to detect malicious software.

User Training

Train users to be aware of access or manipulation attempts by an adversary to reduce the risk of successful spearphishing, social engineering, and other techniques that involve user interaction.

Behavior Prevention on Endpoint

Use capabilities to prevent suspicious behavior patterns from occurring on endpoint systems. This could include suspicious process, file, API call, etc. behavior.

Restrict Web-Based Content

Restrict use of certain websites, block downloads/attachments, block Javascript, restrict browser extensions, etc.

Software Configuration

Implement configuration changes to software (other than the operating system) to mitigate security risks associated to how the software operates.

Audit

Perform audits or scans of systems, permissions, insecure software, insecure configurations, etc. to identify potential weaknesses.

Password Policies

Set and enforce secure password policies for accounts.

Exploit Protection

Use capabilities to detect and block conditions that may lead to or be indicative of a software exploit occurring.

Limit Access to Resource Over Network

Prevent access to file shares, remote access to systems, unnecessary services. Mechanisms to limit access may include use of network concentrators, RDP gateways, etc.

Multi-factor Authentication

Use two or more pieces of evidence to authenticate to a system; such as username and password in addition to a token from a physical smart card or token generator.

Operating System Configuration

Make configuration changes related to the operating system or a common feature of the operating system that result in system hardening against techniques.

Credential Access Protection

Use capabilities to prevent successful credential access by adversaries; including blocking forms of credential dumping.

Privileged Process Integrity

Protect processes with high privileges that can be used to interact with critical system components through use of protected process light, anti-process injection defenses, or other process integrity enforcement measures.

Data Backup

Take and store data backups from end user systems and critical servers. Ensure backup and storage systems are hardened and kept separate from the corporate network to prevent compromise.