A watering hole attack is a security exploit in which the attacker seeks to compromise a specific group of end users by infecting websites that members of the group are known to visit. The goal is to infect a targeted user's computer and gain access to the network at the target's workplace.
The term watering hole attack comes from hunting. Rather than tracking its prey over a long distance, the hunter instead determines where the prey is likely to go, most commonly to a body of water -- the watering hole -- and waits there. When the prey lets its guard down, the hunter attacks.
In the tech world, the target victim can be an individual, an organization or a group. The attacker profiles its targets -- typically, employees of large enterprises, human rights organizations, religious groups or government offices -- to determine the type of websites they frequent. These are often messaging boards or general interest sites popular with the intended target.
While watering hole attacks are uncommon, they pose a considerable cyberthreat because they're difficult to detect and typically target highly secure organizations through their less security-conscious employees, business partners or connected vendors. They can be extremely destructive because they can breach several layers of security.
Watering hole attacks -- a type of social engineering attack -- are also called water-holing, water hole attacks or strategically compromised websites.
How does a watering hole attack work?
A watering hole attack involves a chain of events the attacker initiates to gain access to a victim. However, the attacker does not target the victim directly.
First, the attacker identifies a legitimate website or service that the intended victim already uses and is familiar with. Generally, the target site has relatively low security, is frequently visited and is popular with the intended victim. The attacker then compromises the target site and injects a malicious code payload into the site, often using JavaScript or Hypertext Markup Language. When the victim visits the compromised site, the payload is triggered, beginning an exploit chain that infects their computer. The payload can be automatic, or the attack might cause a bogus prompt to appear, telling the user to take additional action, which downloads malicious code. The exploit chain might be one that already exists and is well known or a novel exploit created by the attacker.
Once the payload has been triggered on the victim's computer, the attacker can access other assets on the network and use that computer to launch a pivot attack to achieve other nefarious goals. The goals might be to gather information about the victim, use the victim's computer as part of a bot network or try to exploit other computers within their network.
Other security exploits similar to watering hole attacks
A watering hole attack is similar to other tactics used by cybercriminals and hackers:
- Supply chain attack. In a supply chain attack and a watering hole attack, the attacker compromises a third-party service to infect other systems. However, in a supply chain attack, a product the target purchases is usually compromised, unlike the neutral websites that are compromised during a watering hole attack.
- Honeypot attack. A honeypot attack presents an attractive target that entices the victim to take action, while a watering hole attack focuses on an existing site the target already uses.
- Man-in-the-middle attack. In a MitM attack, the attacker intercepts and reads or changes communication between the victim and a third-party site, but the site itself is not compromised.
- Tailgating. Tailgating is similar to a watering hole attack in that an attacker follows closely behind someone trusted to gain access, but it is most commonly a physical attack.
- Phishing. Cybercriminals use phishing to lure users to open an email and its attachment or web link. The email appears to have been sent from a party known to the user, such as a colleague or friend. When the user opens the email attachment or web link, malware enters their system. Phishing attacks are typically sent to multiple users to exploit vulnerabilities across a broad user population.
- Spear phishing. Malicious hackers research organizations and target specific users within a company whom they believe have highly sensitive or valuable information. They research these individuals to develop compelling spear phishing emails with attachments and web links that appear to be from someone within the user's organization. Once the user opens the email attachment or web link, malware is planted on their computer.
Signs of a watering hole attack
Watering hole attacks are similar to other types of cyberattacks but are difficult to detect. However, once the perpetrator has bypassed cybersecurity measures and has gained access to systems, apps, users and devices, users might experience the following:
- Computer performance issues and system slowdowns.
- Unexplained system crashes.
- Changes to browser security settings.
- Missing files.
- Ads or pop-ups directing the user to a specific website.
- New or unknown applications downloaded to the user's device.
If a user suspects they are the victim of a watering hole attack, they should avoid clicking on links or downloading files and contact their IT security team immediately.
How to prevent watering hole attacks
The following best practices can help organizations avoid watering hole attacks:
- Use best practices for computer security. Since watering hole attacks are often web exploits, following published best practices and computer hardening guidelines could help prevent these cyberincidents. These include using antivirus software, requiring strong authentication for all users and improving employee security awareness.
- Do not allow personal use of corporate resources. Block access to websites not used for work, and do not allow users to access websites for personal communication.
- Do not add trusts to third-party sites. Some sites require additional permissions to run properly. Audit or don't allow these exceptions, as they could allow an attacker to use the site in the future.
- Train users to recognize strange behavior and avoid violations. Users can be lax with sites they commonly visit, so they should be trained to avoid clicking on suspicious links and not bypass security warnings.
- Scan and monitor internet traffic. Use web proxies that can scan content in real time, monitor for common exploits and use web logging to detect suspicious activity.
Examples of watering hole attacks
The following are notable examples of recent attacks:
- In 2016, a watering hole attack on the Montreal-based International Civil Aviation Organization (ICAO) spread malware that infected its network. The cyberespionage group Emissary Panda, or APT27, accessed the ICAO website through compromised servers. The attack targeted employee data, safety data and sensitive information from other organizations.
- In 2017, a series of cyberattacks hit Ukrainian government websites. The Petya malware compromised the websites of banks, newspapers, ministries and power companies. The targeted attack is believed to have originated with an update to a Ukrainian tax accounting package.
- In 2020, SolarWinds, an IT supply chain software vendor, experienced a watering hole attack. The Russian espionage group Nobelium compromised SolarWind's software by injecting malicious code into updates that were ultimately distributed to the vendor's customers and their partners -- large companies and government agencies. The breach compromised the data, networks and systems of thousands of organizations.
- In 2023, a Japanese university research lab website experienced a watering hole attack. Although this attack, which likely targeted students and researchers, did not infect users' systems with malware, they were tricked into clicking on a pop-up message that downloaded and executed malware disguised as an Adobe Flash Player update.
- In 2024, a watering hole attack on 25 websites linked to the Kurdish minority compromised sensitive user information. The attack, which was dubbed SilentSelfie, involved four different attacks, ranging from stealing user location information to installing malicious applications used on the Android operating system.
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