Nearly everyone has had “that cold,” the one where most symptoms have resolved except that lingering cough. The cough can continue for weeks or months, all while you feel mostly well across the board.
In cybersecurity, an advanced persistent threat (APT) is your IT environment’s lingering cough, albeit a much more damaging one. An APT stealthily gains initial access to your company’s systems and networks, then hides within them to complete objectives. Since advanced persistent threats can cause long-term damage to sensitive systems and data, understanding what they are and why they matter enables you to better protect your organization.
What is an advanced persistent threat?
An advanced persistent threat (APT) is a sophisticated cyberattack where malicious actors gain unauthorized access to the network then linger undetected for an extended time. While traditionally linked to nation-state threat actors, the designation now includes groups that target high-value organizations and entities, like businesses in the government agency supply chain.
APTs seek long-term infiltration so they can conduct corporate or international espionage or sabotage, focusing on data theft rather than system damage for financial gain. To penetrate and maintain a foothold in target systems, APT actors leverage various attack vectors, including social engineering techniques.
The key characteristics of APTs include:
- Targeted Nature: Typically directed at high-value targets, like defense contractors or governmental networks.
- Extended Duration: Maintaining access for an extended period to steal information.
- Stealth Operations: Avoiding detection by security teams to continue stealing data.
- Strategic Goals: Aiming to conduct cyber espionage or corporate espionage while destabilizing critical infrastructures.
What are the 3 Stages of an APT attack?
Sophisticated APT attacks typically have three stages that incorporate multiple steps within them. While these cyber threats may use different tactics and techniques, the process is similar across all types of APTs.
Stage 1: Infiltration
In this initial stage, threat actors gain initial access to the target system and establish a foothold.
Reconnaissance
During this step, the threat actors look for potential weaknesses in the organization’s security. For example, they may:
- Scan networks looking for vulnerabilities in software, hardware, or firmware.
- Identify misconfigurations that create a security weakness.
- Gather information about hosts, user identities, and networks.
Initial access
To gain initial access, APT groups may engage in any or all of the following activities:
- Exploiting vulnerabilities: Using known or unknown vulnerabilities in applications, operating systems, or firmware.
- Credential-based attacks: Trying to compromise user accounts through attacks that target weak or previously compromised credentials, like credential stuffing attacks
- Phishing attacks: Tricking users into share credentials then pretending to be the legitimate users.
- Stealer malware: Deploying malware that captures keystrokes on the devices that connect to the target networks.
- Buying access on the dark web: Purchasing exploits or leaked credentials from Initial Access Brokers (IABs) in illicit cybercriminal forums.
Establish a foothold
After gaining the initial access, the APT attackers typically start by finding a way to keep access to the compromised systems for a long period of time by implementing:
- Backdoors: Creating new points for unauthorized access.
- Rootkits: Deploying malware on devices so they can perform remote actions.
Stage 2: Privilege Escalation and Lateral Movement
During this phase, the attackers investigate the victim’s systems, looking for where the organization stores sensitive data.
Privilege escalation
Often, the initial access comes from a standard user account, limiting what the attackers can do within the system. To reach the intended data, the threat actors must increase their access rights. During this phase, they often seek to takeover administrator accounts or other accounts with privileged access.
Lateral movement
Threat actors may engage in lateral movement before and after escalating privileges. During this phase, the attackers navigate through the network to map out its structure. As they grant themselves additional access, they manipulate more aspects of the system, access critical systems, and expand their control over the connected regions.
Stage 3: Exfiltration
This stage is when the attackers steal the sensitive data while trying to avoid detection. They may attempt to distract the security team by deploying a different attack, like a Distributed Denial of Service (DDoS) or ransomware attack. At this point, they encrypt, compress, and transfer the data to their own servers.
Even after exfiltrating this initial data, they may choose to remain embedded in these systems either to engage in future attacks or data theft.
What are the main motives and targets of an APT attack?
While most cybercriminals are financially motivated, the threat actors engaging in APTs typically seek to steal sensitive intellectual property or classified national intelligence data. The attack’s targets are usually high-value entities, like government agencies or large corporations. By embedding themselves within these systems and giving themselves privileged access, the threat actors engage in malicious activity, like stealing data over extended periods of time. Hiding in the systems makes it difficult for security teams to detect activities.
The attackers typically steal sensitive information as part of:
- Corporate espionage: Using a company’s proprietary intellectual property as a way to gain a competitive edge.
- Cyber espionage: Stealing classified government data, like defense or intelligence information.
How can security teams detect an advanced persistent threat?
Since APTs focus on long-term infiltration, they are sophisticated and stealthy in nature, making them more difficult to detect. However, security teams can incorporate monitoring for these critical signs of potential attack:
- Odd log-ins: Since the threat actors focus on privileged accounts, security teams should focus their monitoring activities on identifying abnormal behavior, like logging in outside of normal business hours.
- Intercepted email: Since the threat actors takeover the account, they may prevent the intended recipients from receiving messages that contain sensitive data.
- Abnormal network traffic: Since the threat actors often exfiltrate high volumes of data, security teams can look for abnormal traffic indicating large downloads or transfers.
- Similar tactics and techniques: Since the threat actors maintain persistence, identifying more than one attack that uses similar tactics or techniques can indicate a potential APT.
Best practices for mitigating, detecting, and responding to APTs
While APTs are challenging to detect, security team can implement security measures and detections to help reduce risk, including:
- Regularly applying security patches to known vulnerabilities to reduce the attack surface
- Creating robust firewall rules and monitoring network traffic for remote data transfers outside of normal business operations.
- Limiting user access to the least amount needed to complete job functions.
- Deploying a privileged access management (PAM) solution for focused monitoring over these high-value privileges.
- Using a virtual private network (VPN) to encrypt remote connections and reduce attacker ability to intercept sensitive data in-transit.
- Mapping detections to the MITRE ATT&CK Framework to focus on known attack tactics and techniques.
- Implementing and automating threat hunting to look for indicators of compromise.
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