The Internet is a busy place. If you look at global web traffic, you might assume that most of it comes from people browsing the news, shopping for gift items, watching videos, or posting on social media. But the reality is different, considering that a good portion of all Internet traffic comes from bots, according to recent reports.
Sure, some of these bots are helpful. Search engines use them to index pages, and customer service tools use them to provide instant chat support. However, a huge portion of this automated traffic is malicious. These are bot attacks, and they are designed to steal data, crash servers, or commit fraud at a scale no human could ever achieve.
In this post, we’ll dive into what bot attacks are, how they happen, and how to detect and mitigate them.
What Is a Bot Attack?
A bot attack is a type of cyberattack where hackers use automated scripts to run repetitive tasks on a website, app, devices, or network. It differs from traditional malware attacks, as bot attacks focus on living off the land, meaning they exploit legitimate site functionality, such as login pages or checkout flows.
Unlike a human hacker who might manually try to guess a password, a bot can attempt thousands of login combinations per second. This speed and volume make bot attacks a major concern for any business with an online presence.
While a single bot can do damage, many attackers use botnets or networks of infected computers and devices controlled by a single attacker, allowing them to launch massive, coordinated strikes.
How Does a Bot Attack Happen?
A bot attack usually follows a lifecycle that starts with infection, followed by target selection, attack launch, and execution.
First, the botmaster, the person or group controlling the attack, writes code or buys a ready-made bot script designed for a specific purpose, such as scraping prices or cracking accounts.
The attacker then identifies a target, which could be anything from an e-commerce site to a list of vulnerable IP addresses. If the attack requires a botnet, the attacker infects thousands of devices with malware. These devices can include computers, smartphones, and even smart home gadgets such as webcams and thermostats.
Once the botnet is ready, the attacker sends commands to the bots, which then flood the target with requests. Because these requests come from many different locations, it is difficult for a simple firewall to distinguish between a malicious bot and a legitimate customer. The attack continues until the goal is met or the bot is blocked by security software.
Types of Bot Attacks
Not all bot attacks look the same. They vary depending on what the attacker wants to achieve. Here are the most common types of bot attacks businesses face today.
Account Takeover (ATO)
In an ATO attack, bots use stolen credentials to gain access to user accounts. Attackers often get these credentials from previous data breaches. Since many people reuse passwords across different sites, a bot can try those combinations on hundreds of other platforms.
Once inside, the attacker can steal credit card information, buy items, change account details, or sell the account on the dark web.
Ad Fraud
Ad fraud bots mimic human behavior by clicking on ads or viewing video content. This drains a company’s marketing budget without ever leading to a real sale. It is a massive problem for the advertising industry, especially since digital advertising relies on clicks and impressions that these bots imitate.
Ad fraud costs companies billions of dollars every year. In 2025 alone, it was estimated that organizations worldwide lost US$150 billion to ad fraud.
Card Fraud
Also known as carding or card cracking, this involves bots testing lists of stolen credit card numbers. They perform small, invisible transactions on a site to see if a card is active. Once they find a working card, the attacker uses it for larger, more expensive purchases elsewhere.
Aside from the credit card owner, the merchant suffers from this type of bot attack as well, as the orders result in chargebacks that can penalize the merchant.
Fake Account Creation
Bots can sign up for thousands of new accounts in minutes. These accounts can be used to spread spam, manipulate social media trends, scrape gated content, or claim new user rewards and discounts.
These fake accounts skew business data and ruin the experience for actual users. It forces the target company to pay for server space, customer support, and marketing for fake users who will never spend any money.
Layer 7 DDoS Attacks
A Distributed Denial of Service (DDoS) attack aims to take a website offline by overwhelming it with traffic. A Layer 7 attack specifically targets the application layer, or the part of the server that processes search, login, and other user requests.
When bots flood these specific functions, they can crash the site with relatively low bandwidth usage.
Scalping
You have probably experienced this if you have ever tried to buy concert tickets or a new game console. Scalping bots are programmed to buy high-demand items the millisecond they go on sale. The attackers then resell these items on third-party sites at a much higher price.
Ticket scalping has even made it to the U.S. Senate agenda, as a Commerce Committee panel held a hearing featuring testimony from singer Kid Rock and a top executive from Live Nation Entertainment.
Scraping
Scraping bots crawl a website to steal content or data. While some scraping is legal, malicious scraping can be used to steal proprietary price lists, copy original blog posts, or gather contact information for spam lists.
These bots give competitors an unearned market edge while diluting the victim’s brand value.
Famous Examples of Bot Attacks
Over the years, several massive attacks have made headlines due to their scale and the damage they caused. Below are some examples:
| Bot Attack | Details |
| EarthLink Spammer | This is one of the earliest examples of a massive botnet. A single person used a botnet to send almost a billion spam emails, eventually resulting in a $16 million legal judgment. |
| Storm | This botnet was one of the first to use a peer-to-peer structure, making it very hard to shut down. At its peak, it controlled millions of computers and was used for everything from identity theft to DDoS attacks. |
| Zeus | Zeus was a banking Trojan that turned infected computers into bots. It was famous for stealing banking information through keystroke logging and man-in-the-browser attacks (bots embed themselves in browser extensions or APIs, acting as proxies between the user and the browser). It eventually resulted in hundreds of millions of dollars in losses worldwide. |
| Kraken | At one point, Kraken was the largest botnet in the world. It was designed to evade traditional antivirus software by constantly updating its own code, allowing it to infect computers in many Fortune 500 companies. |
| Mariposa | The Mariposa botnet infected nearly 13 million computers across 190 countries. It was used to steal credit card details and login credentials before Spanish authorities finally dismantled it. |
| Methbot | This was one of the biggest ad fraud operations. It used a botnet to watch up to 300 million video ads per day and generated between $3 million and $5 million in fraudulent revenue every day. |
| Mirai | Mirai was different from all the other previous botnets because it targeted Internet of Things (IoT) devices like DVRs and IP cameras. It used these devices to launch a massive DDoS attack that took down major parts of the internet, including Twitter, Netflix, and CNN. |
Top 10 Bot Attack Indicators
Detecting a bot attack early can save your business from a disaster. If you notice these patterns, you might be under attack.
- Sudden website traffic spikes: A massive jump in visitors that does not align with a marketing campaign or holiday sale is a major red flag.
- High volume of failed login attempts: If you see thousands of failed logins from different IP addresses, bots are likely trying to brute-force their way into user accounts.
- Sudden website performance issues: If your site becomes sluggish or crashes without a clear reason, a botnet might be hogging your server resources.
- Unusual increases in API traffic: Attackers often target APIs directly because they are sometimes less protected than the main website interface.
- Abnormal account creation patterns: A surge in new accounts using strange email addresses or coming from a single region is a sign of fake account creation bots.
- Irregular browsing behavior: Human users usually click around and spend time on pages. If users are going straight to the checkout or a specific data point and then leaving, they are likely bots.
- Increased chargebacks and fraudulent transactions: A spike in disputed credit card transactions often means carding bots have successfully tested stolen cards on your site.
- Abnormally high bounce rates: If your traffic increases but those visitors leave the site instantly, it could be a bot attack rather than a real interest.
- Abnormal session durations: Sessions that last only a fraction of a second, or stay open for hours without activity, are suspicious.
- Suspicious IP addresses and geographies: If a user logs in from New York and then again from London ten minutes later, that is impossible travel. It usually means a bot is using a proxy server or a stolen session.
How to Prevent Bot Attacks
Cybersecurity experts usually recommend a multi-layered defense as the best bot attack prevention approach since you cannot stop bots from trying to visit your site, but you can stop them from doing damage.
Use Modern CAPTCHA and Challenges
CAPTCHA is the classic way to tell humans and bots apart. Modern versions, such as Google’s reCAPTCHA v3, work in the background. They analyze user behavior to determine whether a user is a bot without making the user click on images of traffic lights or similar challenges.
Rate Limiting and Throttling Requests
Rate limiting sets a cap on how many requests a single IP address can make in a certain timeframe. If a user tries to refresh a page 500 times in a minute, the system automatically blocks them.
Use Web Application Firewalls (WAF)
A WAF sits between your website and the internet, inspecting incoming traffic and blocking known malicious patterns. Many WAFs come with built-in bot protection that can identify common bot signatures.
Employ Bot Management and Mitigation Solutions
Basic security tools catch low-hanging fruit using signature matching. However, modern bots are different since they are built to fly under the radar by acting like humans. To address this evasive nature, advanced bot management uses machine learning to analyze behavior in real time.
These tools look at biometrics, such as mouse movements, scroll speed, and typing rhythms, to tell a human from a script. They also use device fingerprinting to collect data points from the hardware and browser. In the process, a persistent ID for the bot is created so that even if the attacker spins up residential proxies to hide their IP address, the bot management system still detects the same bot.
Set Up Honeypots
A honeypot is a digital tripwire that catches bots using hidden elements. You embed links or form fields in your code that are invisible to humans. While a person never sees these traps, bots parse the HTML and trigger them.
This method is accurate because a human cannot click what they cannot see. Therefore, any interaction proves the visitor is a bot, so you can block the source without false positives.
Implement IP Blacklisting and Geofencing
If you do not do business in a specific country and see massive traffic from that region, you can use geofencing to block all traffic from that area. You can also use blacklists to block IPs known for malicious activity.
Conclusion
Bot attacks have been plaguing the digital world for decades. As bots become smarter and more human-like, businesses must continuously improve their bot attack prevention strategies to stay ahead of the curve.
Organizations must understand these automated threats and monitor for warning signs to protect their systems and data. By doing so, they also secure their customers and their reputation.
