Advanced Persistent Threats/APT Attacks: Detect, Defend, Respond

Advanced Persistent ThreatsAPT Attacks

In the cyber world, perpetrators come in various forms and capabilities. At one end of the spectrum, we have the script kiddies or inexperienced ransomware gangs seeking quick monetary gains. On the other end, state-sponsored groups are employing highly sophisticated tactics driven by long-term strategic objectives. Advanced Persistent Threats/APT attack groups belong to the latter category.

These well-funded organizations consist of elite hackers, honing in on high-value targets such as governments, large corporations, or critical infrastructure. Employing multi-stage, multi-vector approaches with extensive obfuscation and persistence, APTs are formidable adversaries.

Yet, small-to-medium-sized businesses (SMBs) may wonder, “Why would an APT group care about us?”

The answer lies in their potential role as stepping stones to more prominent targets, mainly if they exist within a supply chain or serve larger entities. A staggering 93% of SMB executives believe that nation-state hackers use businesses like theirs as a backdoor into the country’s digital defenses.

What is an Advanced Persistent Threat Attack?

An Advanced Persistent Threat/APT attack is a well-organized cyberattack orchestrated by highly skilled and sophisticated threat actors. Unlike quick and sporadic attacks, APTs involve meticulous planning, focusing on strategic targets, and unfolding over an extended period.

APTs are complex and multi-faceted assaults that encompass various stages and a wide range of attack techniques. Several commonly observed attack vectors originated from APT campaigns, including zero-day exploits, custom-made malware, credential theft tools, and lateral movement techniques. APT campaigns often deploy multiple attack patterns and exploit several access points to achieve their objectives.

The goals pursued by APT attackers and the consequences faced by targeted organizations include:

What are the Three Stages of APT Attacks?

To prevent, detect, and resolve an Advanced Persistent Threat/APT attack, it’s crucial to understand its typical characteristics.

APTs generally follow a basic life cycle involving infiltrating a network, expanding access, and accomplishing their primary objective, often stealing data from the network.

Stage 1: Infiltration

In this initial phase, APTs often gain access through social engineering techniques. They may send targeted emails, known as “spear-phishing,” to specific high-level individuals, like senior executives or technology leaders. These emails might appear from a trusted colleague and could mention ongoing projects. If multiple executives report falling victim to such attacks, it could indicate the presence of an APT.

Stage 2: Escalation & Lateral Movement

Once inside the network, attackers insert malware to expand their reach. They move laterally through the network, mapping it and gathering login credentials to access critical business information. They might create “backdoors” for future stealthy access, ensuring the attack can continue even if one entry point is discovered and closed.

Stage 3: Exfiltration

During this phase, cybercriminals store stolen data in a secure location within the network until they have collected enough information. They then quietly extract, or “exfiltrate,” the data without being detected. To distract security teams, they might employ denial-of-service (DoS) attacks to tie up network personnel while stealing the data. The compromised network remains vulnerable, ready for the attackers to return anytime

Some Real World Examples of APT Attacks

Here are some examples of APT malware-based attacks and the known APT groups associated with them:
  • GhostNet: Based in China, this group utilized spear phishing emails containing malware to conduct attacks. They targeted computers in more than 100 countries, focusing on gaining access to government ministries and embassies’ networks. Once inside, they compromised devices and used cameras and microphones to carry out surveillance.
  • Stuxnet: This worm was designed to attack Iran’s nuclear program and was delivered through infected USB devices. It caused significant damage to the centrifuges used in uranium enrichment. Stuxnet explicitly targets SCADA (Supervisory Control and Data Acquisition) systems, enabling it to disrupt machinery within the Iranian nuclear program without the operators’ knowledge.
  • Deep Panda: Suspected to originate from China, this APT attack targeted the US Government’s Office of Personnel Management in 2015. The attack, code-named Deep Panda, compromised over 4 million US personnel records, potentially including details about Secret Service staff.
  • APT28 (Fancy Bear, Pawn Storm, Sednit): A Russian group identified by Trend Micro in 2014, APT28, conducted attacks against military and government targets in Ukraine and Georgia, as well as NATO organizations and US defense contractors.
  • APT34: Linked to Iran and identified by FireEye researchers in 2017, APT34 targeted government organizations, financial institutions, energy companies, chemical companies, and telecommunications firms in the Middle East.
  • APT37 (Reaper, StarCruft): Likely originating from North Korea, APT37 has been active since 2012. The group is associated with spear phishing attacks, often exploiting the Adobe Flash zero-day vulnerability.

Targets of Man-In-The-Middle Attack

Social engineering is one of APT actors’ oldest yet highly effective tactics to gain initial access to a network by manipulating unsuspecting users or employees. Common attack techniques within social engineering include:


APT groups send well-designed, authentic-looking emails or text messages to create a sense of urgency, fear, or curiosity among targets. It prompts them to reveal sensitive information or unknowingly activate malicious payloads or ransomware.

Spear Phishing

In spear phishing, APT actors specifically target certain individuals or businesses, limiting the size of the target group to increase the chances of successful exploitation. The attackers carefully craft messages tailored to the characteristics and job positions of the targeted individuals, making the attack appear less suspicious. Once clicked, these messages enable threat actors to capture privileged users’ credentials through keyloggers.


Rootkits are malicious software programs that provide attackers remote control over a target system, concealing their presence. Once inside an infected system, rootkits create backdoors, granting APT groups undetected access to the organization’s network. Like email phishing campaigns, common attack vectors are often used to install rootkits.

Exploit Kits

Exploits are shell codes that automatically scan for vulnerabilities in the target system and install malware if found. Exploit kits, on the other hand, contain multiple exploits and are used by APT actors. These kits are deployed on the victim’s system through malicious websites and emails. Clicking links on compromised websites or emails redirects users to attacker-controlled landing pages, which scan for vulnerabilities to launch attacks or install malicious payloads.

Other Methods

APT attacks can take various forms, such as DNS tunneling, rogue Wi-Fi, and drive-by downloads. The selection of APT attack vectors largely depends on the threat actors’ intentions and attack strategy.

Signs that Show APT Attack in an Enterprise

As APTs primarily aim is to exfiltrate data, attackers often leave evidence of their malicious activities. Some significant indicators, according to CSO, include:
In a recent Threat Hunting webinar, security experts provided additional insights on identifying APT attacks. They advised looking for command shells (WMI, CMD, and PowerShell) that establish network connections or remote server tools on non-administrator systems.
Furthermore, they recommended monitoring for any suspicious Microsoft Office documents, Flash, or Java incidents that initiate new processes or spawn command shells.
Deviation in the typical behaviors of administrator accounts, such as the creation of new accounts locally or within a company’s domain, as well as unusual parent processes for core Windows processes (e.g., lsass, svchost, or csrss), can also serve as evidence of an APT in the environment.
Lastly, it is worth noting that “57% of enterprise, government, and educational organizations rate APIs as a top security concern,” emphasizing the importance of securing Application Programming Interfaces (APIs) as part of the overall security strategy to mitigate APT risks.

How to Prevent Advanced Persistent Threats/APT Attacks?

Effective APT detection and protection require collaboration among network administrators, security providers, and individual users. Implementing a multi-faceted approach enhances security measures. Here are key practices to consider:

Traffic Monitoring

Application and Domain Whitelisting

Access Control

Additional Best Practice Measures

Access Control

Promptly apply patches to network software and operating systems to address vulnerabilities and prevent exploitation.


Encrypt remote connections to safeguard against intruders infiltrating the network through unsecured connections.

Email Filtering

Implement email filtering to prevent spam and phishing attacks that may target the network.


Ensure immediate logging of security events to enhance whitelists and other security policies, enabling proactive responses to potential threats.


A proactive approach is crucial in the face of Advanced Persistent Threats (APTs). Detection through traffic monitoring and access controls, coupled with defense measures like whitelisting and two-factor authentication, strengthens security.

Swift response strategies, such as patching and email filtering, enhance resilience. Staying vigilant and adaptable is paramount to safeguarding assets and data and ensuring a secure digital future.

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