Cyber Threat Report: 'Fortinet Zero-Day and Custom Malware Used by Suspected Chinese Actor in Espionage Operation'

This blog post by threat researchers at Mandiant outlines intrusions activity by the UNC3886 intrusion set which involved the deployment of backdoors to Fortinet and VMWare platforms. The actor used a directory traversal zero-day (CVE-2022-41328) to deploy capabilities to FortiGate firewall devices. The actor was then able to redirect traffic on the devices and gain persistence on FortiManager and FortiAnalyzer devices. The group has also been observed deploying a VMWare ESXi hypervisor malware framework and Mandiant analysts observed connections between compromised Fortinet devices and 'VIRTUALPITA' backdoors on VMWare systems. Mandiant attribute UNC3886 as an advanced espionage group with a suspected China nexus.

Network Intrusion Prevention

Use intrusion detection signatures to block traffic at network boundaries.

Execution Prevention

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

Audit

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

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.

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.

Exploit Protection

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

Password Policies

Set and enforce secure password policies for accounts.

Update Software

Perform regular software updates to mitigate exploitation risk.

Software Configuration

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

Active Directory Configuration

Configure Active Directory to prevent use of certain techniques; use SID Filtering, etc.

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.

Privileged Account Management

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

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.

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.

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.

Limit Software Installation

Block users or groups from installing unapproved software.

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...

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.

Environment Variable Permissions

Prevent modification of environment variables by unauthorized users and groups.

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.

User Account Management

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

Application Developer Guidance

This mitigation describes any guidance or training given to developers of applications to avoid introducing security weaknesses that an adversary may be able to take advantage of.

Account Use Policies

Configure features related to account use like login attempt lockouts, specific login times, etc.

Disable or Remove Feature or Program

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

Restrict Web-Based Content

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

Code Signing

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