Cyber Threat Report: 'PRC State-Sponsored Actors Compromise and Maintain Persistent Access to U.S. Critical Infrastructure'

Following an initial advisory issued in May 2023, this advisory from CISA, NSA and partners outlines information on the broader campaign of cyber attacks carried out by Volt Typhoon against critical infrastructure organizations in the US and it's territories, including Guam. The report describes the tactics, techniques and procedures (TTPs) used by Volt Typhoon, including the use of extensive pre-compromise reconnaissance, initial access through exploitation of vulnerabilities in public-facing network appliances and living-off-the-land techniques.

Pre-compromise

This category is used for any applicable mitigation activities that apply to techniques occurring before an adversary gains Initial Access, such as Reconnaissance and Resource Development techniques.

Network Intrusion Prevention

Use intrusion detection signatures to block traffic at network boundaries.

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.

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...

SSL/TLS Inspection

Break and inspect SSL/TLS sessions to look at encrypted web traffic for adversary activity.

Audit

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

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.

Active Directory Configuration

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

Privileged Account Management

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

Account Use Policies

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

Password Policies

Set and enforce secure password policies for accounts.

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.

Disable or Remove Feature or Program

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

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.

Encrypt Sensitive Information

Protect sensitive information with strong encryption.

Update Software

Perform regular software updates to mitigate exploitation risk.

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.

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.

Execution Prevention

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

Exploit Protection

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

Antivirus/Antimalware

Use signatures or heuristics to detect malicious software.

Restrict Registry Permissions

Restrict the ability to modify certain hives or keys in the Windows Registry.

Code Signing

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

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.

Threat Intelligence Program

A threat intelligence program helps an organization generate their own threat intelligence information and track trends to inform defensive priorities to mitigate risk.

Application Isolation and Sandboxing

Restrict execution of code to a virtual environment on or in transit to an endpoint system.

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.

Restrict Web-Based Content

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

Vulnerability Scanning

Vulnerability scanning is used to find potentially exploitable software vulnerabilities to remediate them.