An advanced persistent threat (APT) is defined as a sophisticated, multi-staged cyberattack whereby an intruder establishes and maintains an undetected presence within an organization's network over an extended period of time.
The target may be a government or a private organization and the purpose may be to extract information for theft or to cause other harm. An APT may be launched against one entity’s systems to gain access to another high-value target. Both private criminals and state actors are known to carry out APTs.
The groups of threat actors that pose these APTs are carefully tracked by multiple organizations. Security firm CrowdStrike tracks over 170 APT groups, and reports having observed a nearly 45% increase in interactive intrusion campaigns from 2020 to 2021. While (financial) e-crime is still the most common motive identified, nation-state espionage actions are growing more rapidly and now a strong second in frequency.
An APT is comprised of three main stages:
Because the threat is designed to both avoid detection and reach very sensitive information or processes, each of these stages may involve multiple steps and be patiently conducted over an extended period of time. Successful breaches may operate undetected over years; but some actions, such as jumping from a third-party provider to the ultimate target or executing a financial exfiltration, may be done very rapidly.
APTs are known for using misdirection to avoid correct, direct attribution of its work. To throw off investigators, an APT for one country might embed language from another country within their code. Investigating firms may have close relationships with a government’s intelligence agencies, leading some to question the objectivity of their findings. But especially with widespread attacks, consensus may be found.
Perhaps the best-known recent APT is the SolarWinds Sunburst attack that was discovered in 2020, but problematic well into 2021. The U.S. Government Accountability Office (GAO) provides a timeline of its discovery and the private and public sector response. Another recently discovered APT is Aquatic Panda, which is believed to be a Chinese group. As listed in MITRE’s ATT&CK database, it is believed to have been active since at least May 2020, conducting both intelligence collection and industrial espionage primarily in technology and telecom markets and the government sector.
The tactics, techniques and procedures (TTPs) of APTs are regularly updated in response to constantly evolving environments and countermeasures. Trellix’s Head of Threat Intelligence reports, “This past year, there was a dramatic uptick in APT attacks on critical infrastructure such as the transportation and financial sectors.”
As Gartner analyst Ruggero Contu has noted, “The pandemic accelerated hybrid work and the shift to the cloud, challenging the CISO to secure an increasingly distributed enterprise. The modern CISO needs to focus on an expanding attack surface created by digital transformation initiatives such as cloud adoption, IT/OT-IoT convergence, remote working, and third-party infrastructure integration.”
Threat actors employ continuous and often complex hacking techniques. They typically perform a thorough analysis of a company, review its leadership team, profile its users and obtain other in-depth details about what it takes to run the business. Based on this assessment, attackers attempt to install one or more backdoors so that they can gain access to an environment without being detected.
The lifecycle of an advanced persistent threat
Lockheed Martin’s cyber kill chain framework serves as a helpful reference for the lifecycle of advanced persistent threats. The process consists of seven steps, beginning with reconnaissance.
The basic cyber kill chain model steps are the following:
1. Reconnaissance
2. Weaponization
3. Delivery
4. Exploitation
5. Installation
6. Command and Control
7. Actions on Objective
8. Monetization: This eighth step has been added by some to the original model.
Attackers will analyze the leadership team, they will analyze the type of business, and they will understand exactly what type of target it is. As the attack evolves from reconnaissance to weaponization, attackers will determine the most efficient method for exploiting vulnerabilities.
The attacker may exploit vulnerabilities in systems and cloud services, or they may exploit employees through phishing-style attacks. Having selected the approach or approaches that they wish to take, they will deliver malware or exploit vulnerabilities that will allow them access to the environment. An attacker will then install a remote-access Trojan or a backdoor mechanism to maintain persistent access to the system.
It is common for a command-and-control system to be set up where the environment sends out heartbeats to an external server or service so that the attacker may execute or download malicious files to the environment, or exfiltrate data out of the environment.
This is a useful model, but cyber-attackers have adapted to it. They sometimes skip steps or combine several of them into one action to reduce the time needed to infiltrate and infect. As part of the process, bad actors will develop customized tools (or acquire them on the dark web) to attack a specific organization or type of organization.
In some cases, cybercriminals have become deft at covering their tracks. By remaining undetected, they have the opportunity to use back doors over and over for additional raids.
As well as there being a lifecycle for one advanced persistent threat, there is also the lifecycle of the attackers to consider. Carric Dooley, managing director of incident response at Cerberus Sentinel, notes that the groups tend to evolve as well as come and go over time.
He gives the example of DarkSide, which became DarkMatter, and has now spun off into the BlackCat criminal group.
“They evolve their approach, [their] tooling, how they define and select targets, and business models based on staying ahead of the good guys using ‘what works today’,” he said. “Some take a break after making a pile of cash and some retire or let the heat from law enforcement die down.”
Thus, some APT groups remain active over the long term. Others that have been dormant for many years suddenly get back into business. But it is hard for the defending organizations or nations to accurately categorize who or what is attacking them. Apart from the obfuscation techniques delivered by nation state-sponsored actors, it may be that APT groups perceived as different are actually one entity but the individuals that compose them and their malware tools are changing and evolving.
List of key threats
By their nature, new advanced persistent threats based on novel techniques are commonly operating without yet having been detected. Moreover, especially challenging attacks may still be perpetrated on organizations long after they were initially identified (e.g. SolarWinds).
However, new common trends and patterns are regularly recognized and replicated until the means are found to render them ineffective. Kaspersky, a Russian internet security firm, has identified the following major trends in APTs:
10 examples of advanced persistent threat groups
APTs can’t be thought of in the same way as the latest strain of malware. They should be considered to be threat groups that use a variety of different techniques. Once an APT gains success, it tends to operate for quite some time. Here are some examples from MITRE’s database:
10 best practices for advanced persistent threat identification and management
It is inherently difficult to identify APTs. They are designed to be stealthy, facilitated by the development and illicit traffic in zero-day exploits. By definition, zero-day exploits cannot be directly detected. However, attacks tend to follow certain patterns, pursuing predictable targets such as administrative credentials and privileged data repositories representing critical enterprise assets. Here are 10 tips and best practices for avoiding and identifying APT intrusion:
1. Threat modeling and instrumentation: “Threat modeling is a useful practice that helps defenders understand their risk posture from an attacker’s perspective, informing architecture and design decisions around security controls,” according to Igor Volovich, vice president of compliance for Qmulos. “Instrumenting the environment with effective controls capable of detecting malicious activity based on intent rather than specific technique is a strategic direction that enterprises should pursue.”
2. Stay vigilant: Pay attention to security analyst and security community postings that keep track of APT groups. They look for related activities that indicate the actions of threat groups, activity groups and threat actors, as well as signs of activities such as new intrusion sets and cyber-campaigns. Organizations can gain intelligence from these sources and use it to analyze their own assets to see if they overlap with any known group motivations or attack methods. They can then take appropriate action to safeguard their organizations.
3. Baseline: In order to detect anomalous behavior in the environment and thereby spot the tell-tale signs of the presence of APTs, it is important to know your own environment and establish a common baseline. By referring to this baseline, it becomes easier to spot odd traffic patterns and unusual behavior.
4. Use your tools: It may be possible to identify APTs using existing security tools such as endpoint protection, network intrusion prevention systems, firewalls and email protections. Additionally, consistent vulnerability management and the use of observability tools along with quarterly audits can be helpful in deterring an advanced persistent threat. With full log visibility from multiple layers of security technology, it may be possible to isolate actions associated with known malicious traffic.
5. Threat Intelligence: Data from security tools and information on potentially anomalous traffic should be reviewed against threat intelligence sources. Threat feeds can help organizations clearly articulate the threat and what it can potentially mean to the affected organization. Such tools can assist a management team in understanding who might have attacked them and what their motives might have been.
6. Expect an attack: Advanced persistent threats are generally associated with state-sponsored cyberattacks. But public and private sector organizations have also been hit. Financial and tech companies are considered at greater risk, but these days no one should assume they will never receive such an attack, even SMBs. “Any organization that stores or transmits sensitive personal data can be a target,” says Lou Fiorello, vice president and general manager of security products at ServiceNow. “It stems, in part, from the rise of commodity malware: We are seeing some crime groups gaining large amounts of wealth from their nefarious activities that enable them to purchase and exploit zero-day vulnerabilities.”
7. Focus on intent: Volovich recommends that organizations adopt controls capable of detecting malicious activity based on intent rather than a specific technique as a strategic direction that enterprises should pursue in thwarting APTs. This can be looked upon as an outcomes-based risk management strategy that informs tactical decisions about tool portfolios and investment priorities, as well as architecture and design direction for critical applications and workflows.
8. Compliance: As part of ongoing compliance initiatives, organizations should establish a solid foundation of security controls aligned to a common framework such as NIST 800-53 or ISO 27001. Map current and planned technology investments to the chosen framework’s control objectives to identify any gaps to be filled or mitigated.
9. Know your tools and frameworks: Some organizations go to great lengths to comply with every line item in one security or compliance framework or another. However, this can take on the color of achieving compliance for its own sake (which may be required in some industries). Various compliance and security frameworks should serve as useful guides as well as models for consistent management of risk, but they are not the ultimate objective of a program that will stop APTs in their tracks. Focus on assessing and improving the maturity of the controls and tools themselves and your overall capacity for managing risk.
Vendors and service providers tasked with helping organizations respond to an incident know this well: The victims are often guilty of not even covering security program hygiene at a basic level. Some have little or no detection and response capability, so they miss obvious signs of APT activity. This boils down to implementing standards, frameworks and tools superficially. These organizations did not take the extra steps of ensuring that IT and security personnel become skilled (and certified) in their use.
“Having a tool isn’t the same as knowing how to use it and achieving mastery,” Dooley observes. “I can go buy a combo table saw, router and lathe, but with no experience, what do you think my furniture will look like?”
10. Simple fundamentals: There are so many security systems out there, and so many new ones appearing every month, that it is easy to lose track of the fundamentals. Despite all the complexity and sophistication behind the APT, malicious actors often make their initial forays using the simplest attack vectors. They use all manner of phishing techniques to trick users into installing applications or letting them into systems. Two actions that should now be regarded as essential are security awareness training of all employees to guard against social engineering, and two-factor authentication.
“A key component of reducing risk is training your users on how to identify and respond to phishing attempts,” offers Brad Wolf, senior vice president, IT operations at NeoSystems. “A password alone is insufficient to protect yourself against today's threat landscape; enable two-factor authentication if you haven't done so yet.”