The internet runs on bots. From search engine bots that scan and index websites to RSS feed bots that tee up content for subscribers, bots provide a wealth of creature comforts that serve as the backbone for modern internet navigation. Of course, there are also bad bots designed to do harmful things, usually without anyone noticing at first.
Malicious bots come in various forms, each with its unique methods of disrupting digital ecosystems. From credential stuffing bots seeking unauthorized access to user accounts to scraper bots extracting proprietary data without consent, the landscape of bad bots is vast and varied. These digital troublemakers are efficient and work nonstop to exploit websites, apps, and users, and many modern bad bots can successfully mimic human behavior to evade detection. In addition to outright malicious bots, there is a large spectrum of bots that, while not necessarily malicious, might be unwanted because they impact site performance or enable content reuse.
Recognizing and understanding the risk of malicious bots is crucial for any business operating online. After all, malicious bots aren’t just a nuisance. They pose a risk to the continuity of your business operations and can have a direct, adverse impact on your customers’ experience and bottom line.
Why It’s Important to Identify Good vs. Bad Bot Traffic
Creating a secure, performative digital experience isn’t as simple as just blocking bot traffic. Good bots help your site grow and can improve visibility, user experience, and automation. That’s why effective bot management is about balance—letting the good bots in while keeping the bad ones out.
Here are some examples of friendly bots that help your website:
Good Bots
- Search Engine Bots: Every business wants its website to rank on Google, which means you need search engine bots. These bots scan and index websites so they can appear in search engine results.
- Monitoring Bots: Your website is your brand and it should remain accessible and performative. Monitoring bots help track website performance and can send alerts if something goes wrong.
- Chat Bots: Many websites leverage chatbots to assist customers with common questions, guide them to the right product, or connect them to a support agent.
- AI and Language Model Crawlers: AI companies rely on bots to crawl the internet and train popular large language models (LLMs) to provide better responses. These bots should respect opt-out rules located in the robots.txt file and are considered friendly as long as they follow the website’s guidelines.
Understanding the differences between good and bad bots can help users and businesses implement effective security measures, protect user data, and maintain a positive brand reputation.
Common Malicious Bots and the Risks They Pose
Not all malicious traffic looks suspicious at first glance. Malicious bots can mimic real users and even good bots, making them harder to detect and harder to stop. By understanding the types of bad bots and how they can impact your business, you can take proactive steps to stop these bots from impacting your business.
1. Credential Stuffing Bots
By now, most of us have had our information exposed in a large-scale data breach. What users (and some businesses) may not realize is that these stolen credentials are sold and traded by cybercriminals to use in subsequent cyberattacks.
Credential stuffing bots automate the testing of stolen usernames and passwords against different websites. If the bot finds a username and password combination that works, it can gain unauthorized access to a legitimate user’s account and take it over. From here, the cybercriminal can commit further fraudulent or malicious activities.
2. Carding Bots
Carding bots focus on testing stolen credit card information by making small purchases. These bots aim to verify whether the cards are still active. Once verified, the information can be used for fraudulent activities or sold on the dark web to other criminals. The most common targets for these types of attacks are eCommerce platforms.
3. Impersonator Bots
These bots disguise themselves as search engine bots to sneak past filters that typically only allow access to trusted bots. Because impersonator bots blend in with legitimate traffic, they’re harder to detect, and harder to block. These bots often target industries with high-value data and public-facing platforms and may even exploit public-facing apps and APIs.
4. Web Scraping Bots
Scraper bots are designed to harvest data from websites. These bots download everything—articles, images, or videos in bulk to repost them elsewhere without permission, thereby violating copyright laws and adversely impacting the content owner.
5. Social Media Bots
Social media bots automate interactions on platforms like LinkedIn, Instagram, or X (formerly Twitter) by posting content and comments on these platforms. While some aim to increase user engagement by performing tasks at scale, such as liking posts or following accounts, others have malicious purposes. They can spread misinformation, post links as part of a phishing attack, or manipulate public opinion.
6. DDoS Bots
Distributed Denial-of-Service (DDoS) bots flood websites and applications with malicious traffic, causing them to crash and become unavailable. DDoS bots are commonly called a botnet because they have a unified command and control infrastructure. Their primary goal is to disrupt service availability. The impacts of a DDoS bot attack can be severe, sometimes affecting thousands of websites and apps at once if they are directed against a hosting provider, and the impacts of these attacks can lead to extended downtime, lost revenue, and damaged brand reputation.
7. Inventory Hoarding Bots
Have you ever wanted a pair of new sneakers or tried to purchase a popular new electronics item only to find it sold out the second it launched? If so, then you’re familiar with inventory hoarding bots, sometimes called “scalping bots.”
These bots are programmed to snatch up limited stock items from online retailers. The goal is to buy out inventory, making it scarce for legitimate customers. Often, these items are then resold, or scalped, at significantly higher prices, creating an inflated secondhand market, disrupting fair competition and frustrating customers.
8. Spam Bots
Spam bots are used to distribute unsolicited advertising and repetitive messages across social media and other platforms that have user-generated content. They flood comments, forums, and email inboxes with advertisements or malicious links. These bots can clog communication channels and potentially harm a website’s reputation.
9. Click Fraud Bots
Click fraud bots simulate user clicks on online ads, links, or other clickable elements without being a real buyer with genuine interest. This activity can rapidly deplete a company’s advertising budget while providing no real customer interactions or sales leads. These bots can lead to financial losses for advertisers and potential revenue gains for competitors.
10. Malware Delivery Bots
These bots distribute malicious software across networks or devices. Malware delivery bots often operate as part of larger botnets, scanning for vulnerable systems and deploying payloads like ransomware, spyware, or trojans without user interaction.
Identifying and managing malicious bots isn’t just about security—it’s about safeguarding trust, revenue, and operational integrity.
How To Detect Bot Traffic in Web Analytics
A critical step in setting up a bot mitigation strategy is detecting bot traffic in your web analytics. Bots can significantly distort your understanding of real user behavior, and malicious bots in particular can inflate metrics like pageviews, bounce rates, or conversion attempts. There are a few telltale signs of bot activity you may notice in your web analytics:
- Traffic Spike Without Cause: A sudden surge in traffic without any marketing effort may indicate bots.
- High Bounce Rate: Bots often visit pages without interacting, leading to a high bounce rate.
- Unusual Visitor Location: If there’s a significant amount of traffic from unexpected geographies, it could be bot-driven.
- Low Time on Page: Bots skim through pages quickly, resulting in brief session durations.
- Irregular Visiting Hours: An unusual pattern of visits during odd hours often points to bot activity.
- Referral Spam: Traffic from suspicious websites often results from bots.
By monitoring these indicators, you can make informed decisions about bot mitigation techniques and implement security measures to enhance the overall performance of your website.
Malicious Bot Detection and Prevention Techniques
Just as bots have evolved, so too have bot detection strategies. IP blocking and even CAPTCHA challenges (yes, some bots can solve these now) alone are no longer sufficient to detect and block malicious bot traffic.
A multi-layered, defense-in-depth strategy is the best defense against bot attacks. This approach involves employing a combination of tools and techniques to accurately identify and reduce automated or fraudulent activities.
For a deeper dive, check out Protect Your Business from Malware and Bots and Botnets.
IP Reputation
IP reputation checks help identify whether an incoming IP address is associated with malicious activity such as spam, malware distribution, or bot attacks. Traffic from flagged IPs can then be blocked or monitored more closely to reduce risk.
User-Agent Check
Every client request includes a User-Agent string, which identifies the browser, operating system, and device being used. While bots can spoof these strings, patterns like outdated browsers or inconsistencies across requests can raise red flags. Cross-referencing with known valid User-Agents helps differentiate human users from automated traffic.
Use HTTP Rate Controls
Bots often generate traffic at volumes or speeds that humans wouldn’t. By setting thresholds for how many requests can be made over a short period, it’s possible to detect and throttle suspicious activity.
Implement Behavioral Analysis
Bots often behave differently from humans, like clicking rapidly or skipping page scrolling. Tracking these interactions helps detect and filter out automated threats in real time.
TLS or JA3 Fingerprinting
JA3 fingerprinting identifies SSL/TLS clients by analyzing how they initiate encrypted connections. Each client has a unique fingerprint based on protocol versions, cipher suites, and extensions. Malicious bots often use unusual or inconsistent TLS signatures, helping distinguish them from legitimate browsers.
Check Client-Side JavaScript Execution
Bots struggle with JavaScript. Monitoring whether scripts load and behave as expected helps flag bots that fake headers but fail deeper functionality. This approach filters out non-browser automation tools that skip or misinterpret client-side logic.
Big Data Techniques
Advanced bot management solutions use a wide variety of data in web requests to identify bots, even as the bots morph to evade detection.
Block Bad Bots
Once a bot is identified as malicious or disruptive, blocking it helps protect site performance and user data. This can be done at the firewall, application layer, or through a bot manager. Blocking decisions should be informed by intent and impact, with ongoing monitoring to catch new threats.
Allow Friendly Bots
Friendly bots, like Google’s search engine crawler, uptime bots that monitor website performance, and any bots used by critical business partners, should be allowed access to your site. Maintaining an allow list ensures these bots can access your site without being mistakenly blocked.
Denied Bots
Implement comprehensive bot protection solutions (such as a bot manager) to effectively block high-risk or flagged bots, preventing them from accessing your systems. This approach ensures that malicious bot activities are minimized, safeguarding your digital assets and user data. Additionally, maintain and regularly update deny lists to counteract newly identified bots, adapting to the ever-evolving threat landscape.
HTTP 429 Response
A “Too Many Requests” (HTTP 429) response slows or stops bots making excessive requests, preserving resources and improving stability. This helps mitigate scraping, brute-force, or accidental overloads. It also preserves server resources and prioritizes access for legitimate users.
Serve Only Cached Content
Serving cached versions of your website to bots reduces backend load and protects against unnecessary resource consumption. It ensures bots get the data they’re after without impacting site performance for real users. This is especially useful for high-frequency, low-value bot requests like version checks or content polling.
Block Bots, Not Customers with UltraBot Manager
Bots have evolved into sophisticated tools capable of sneaking past your defenses. One of the most effective things businesses can do is leverage a robust bot management and mitigation strategy. A good bot management solution should be frictionless, easily integrating with your environment to provide rapid value and enhance the customer experience.
Bots aren’t a problem with UltraBot Manager. Our solution enables organizations to quickly identify and block malicious bot traffic, accelerating time to value with deployments that require no app instrumentation or modification.
Interested in learning more? Get in touch with us to tailor a solution that meets your unique needs.
