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How to Spot (and Stop) Ad Fraud in Programmatic Campaigns

Every year, brands lose billions to fake clicks, bot traffic, and deceptive inventory, wasting budget that could fuel real growth.

Your campaigns don't need to accept this loss. By understanding what ad fraud is, recognizing its red flags, and using targeted solutions, you can protect your campaigns and ensure every dollar drives real results.

This guide provides a step-by-step approach to defending your programmatic spend, offering practical guidance.  

What Is Ad Fraud, Exactly?

At its core, ad fraud is any deliberate, deceptive practice that manipulates programmatic ad systems to generate false revenue for fraudsters (e.g., fake publishers, bot networks) while draining advertiser budgets. Unlike accidental inefficiencies, such as poor targeting or low-performing creatives, ad fraud is intentional: fraudsters design schemes to trick platforms into counting “engagement” that never comes from real, interested users.  

Common types of programmatic ad fraud include:  

  • Bot traffic: Automated software (bots) that mimics human behavior—clicking ads, viewing impressions, or watching videos—to fake engagement. These bots are lines of code designed to inflate metrics.
  • Click farms: Networks of low-wage workers (or bots) that manually click ads in bulk, often from shared devices or IP addresses.
  • Domain spoofing: Fraudsters “spoof” (fake) high-quality, brand-safe domains (e.g., CNN.com or TheNewYorkTimes.com) to sell ad space at premium prices. In reality, your ad runs on a low-quality, irrelevant site (or no site at all).
  • Ad stacking: Multiple ads are layered on top of each other in a single ad slot. Only the top ad is visible to users, but you pay for all “impressions”, even the hidden ones.
  • Pixel stuffing: Ads are shrunk to tiny, invisible sizes (e.g., 1x1 pixels) that no human can see. You still pay for the “impression,” but your ad never has a chance to drive engagement.

The Global Cost of Ad Fraud: Why It Matters to Your Brand

Ad fraud is far from a minor issue; it’s a crisis totaling over $114 billion and still growing. According to Statista, global ad fraud costs are projected to increase from $114 billion in 2025 to $172 billion by 2028. This massive scale shows why taking proactive steps to prevent fraud is essential for advertisers.

For individual brands, this leads to wasted budget. A 2023 report by the Association of National Advertisers found that advertisers are wasting 15% of the $88 billion spent on programmatic advertising on MFA (Made for Advertising) websites. This has sounded an alarm for the industry, highlighting a crisis of wasted funds and an overabundance of low-quality ad slots.

But the cost of ad fraud goes beyond money. It also:  

  • Skews your data

If 30% of your “clicks” come from bots, you’ll incorrectly assume your creative or targeting is working, leading to bad strategy decisions (e.g., doubling down on a campaign that only “performs” because of fraud).  

  • Erodes trust

If your ads run on low-quality or harmful sites (via domain spoofing), it damages your brand reputation. Users associate your brand with the sites they see your ads on, and that association can be hard to reverse.  

  • Wastes time

Your team spends hours analyzing false data, troubleshooting “underperforming” campaigns, and chasing leads that don’t exist—time that could be spent on high-impact work.  

Why Is Ad Fraud So Costly?

The global cost of ad fraud keeps rising for three critical reasons, all of which make it harder for brands to defend themselves:  

1. Programmatic’s Scale Creates Opportunities for Fraud

Programmatic advertising processes billions of ad impressions every day, matching advertisers to publishers in milliseconds. This speed and scale are what make programmatic efficient, but they also create gaps for fraudsters. With so many transactions happening in real time, it’s easy for fake traffic to slip through manual checks.  

For example, a fraudster can launch a bot network that generates 10,000 fake impressions in 60 seconds. By the time a human reviewer notices, the fraudster has already been paid for those impressions.  

2. Fraudsters Use Advanced Technology to Avoid Detection

Fraudsters now use advanced tech to evade detection. They leverage AI to mimic human actions like pausing videos or scrolling before ad clicks, and tools like VPNs to hide their location, making fake traffic hard to trace.

Adding to this challenge, internet traffic is increasingly non-human. Automated traffic now makes up 51% of all web traffic, and over two-thirds of that is from “bad bots” that mimic human behavior to commit fraud. This makes spotting fraud with basic checks (e.g., “does this user click too fast?”) nearly impossible.

3. Fragmented Ad Tech Makes Accountability Hard

The programmatic ecosystem is made up of dozens of players: DSPs (demand-side platforms), SSPs (supply-side platforms), ad exchanges, publishers, and verification tools. This fragmentation means no single party is fully responsible for stopping fraud. A publisher might blame a DSP for sending fake traffic; a DSP might blame a verification tool for missing it. Meanwhile, your budget keeps bleeding.  

6 Clear Signals of Ad Fraud in Your Programmatic Campaigns

You don’t need to be a fraud expert to spot red flags; you just need to know what to look for. Below are the most common signs that your programmatic campaign is targeted by fraud, along with how to interpret them:  

1. Unnatural Spikes in Clicks or Impressions

Healthy campaigns see steady, gradual changes in engagement. If your clicks or impressions jump 5x overnight with no changes to your budget, targeting, or creative—it’s a major red flag.  

For example: A campaign that normally gets 300 clicks per day suddenly hits 1,800 clicks. When you check the time of day, 90% of those clicks happen between 2–4 AM (your target audience is in the U.S., so this is midnight–2 AM local time). Real users don’t click ads en masse in the middle of the night; this is bot traffic.  

2. Abnormally CTR and Low Conversion Rates

A strong CTR (Click-Through Rate) is great, but only if it’s realistic. The average CTR for programmatic display ads is 0.1–0.3%; some recent industry data even shows it can be as low as 0.08%. If your CTR is 2% or higher (and you don’t have a viral ad or limited-time offer driving it), fraud is likely.

Why? Bots are programmed to click ads repeatedly to inflate CTR. Fraudsters know advertisers value high CTR, so they use this tactic to make fake traffic look legitimate.  

Real users click ads because they’re interested in your offer. If you have 1,000 clicks but only 2 conversions (a click-to-conversion rate of 0.2%), those clicks are probably fake.  

3. Traffic From Untargeted Regions or IPs

If you’re targeting U.S. users but 40% of your traffic comes from countries you didn’t select (e.g., Nigeria, Bangladesh, or Russia), it’s fake. Fraudsters often use IPs from low-cost regions to run bot networks. These regions have cheaper server costs, making it easier to scale fraud.  

Other IP red flags:  

  • Multiple clicks from the same IP address (e.g., 50 clicks from one IP in an hour).
  • IPs labeled as “data centers” (most real users browse from residential IPs).

4. Low Viewability Rates

Viewability measures whether your ad is actually seen by a human. A “viewable” display ad is 50% visible for at least 1 second; for video ads, it’s 50% visible for 2 seconds.  

If your viewability rate is below 50%, fraud is likely. This could mean your ad is stacked under other ads, stuffed into a tiny pixel, or placed on a page no one visits. Even if you don’t pay for “non-viewable” impressions (many platforms offer viewability guarantees), low viewability wastes your time. Your ad can’t drive results if it’s hidden.

5. Strange User Agent Strings

A “user agent” is a line of text that identifies a user’s device, browser, and operating system (e.g., “Mozilla/5.0 (iPhone; CPU iPhone OS 17_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.0 Mobile/15E148 Safari/604.1”).  

Fraudulent traffic often has suspicious user agents:  

  • Outdated browsers (e.g., Internet Explorer 6, discontinued in 2016).
  • Mismatched devices and browsers (e.g., an “iPhone” running “Windows 10”).
  • Generic labels like “Bot/1.0” (no specific device or browser listed).

6. Zero Session Duration

Session duration measures the total length of time a user spends on a website or app during a single "session." Real users will spend time on your landing page, even if they do not convert. If 80% of your "visitors" have a session duration of 0–1 second, they are bots. Bots click your ad and leave immediately (a tactic used to avoid detection), whereas real users take time to read your content or explore your offer.

What Can Brands Do to Stop Ad Fraud? 5 Actionable Steps

Spotting fraud is the first step—stopping it requires a mix of tools, strategy, and ongoing monitoring. Below are the most effective ways to protect your programmatic campaigns:  

Step 1: Use Real-Time Ad Verification Tools

Ad verification tools scan your traffic for fraud signals (e.g., bots, spoofed domains) and block suspicious activity before it wastes your budget. The best tools work in real time, so you don’t have to wait to act.  

Key features to look for:  

  • Bot detection: Identifies and blocks known bot networks.
  • Domain verification: Ensures your ad runs on the exact domains you target (no spoofing).
  • Viewability tracking: Blocks non-viewable impressions automatically.

Step 2: Tighten Targeting to Filter Fake Traffic

Precise targeting reduces your exposure to fraud by limiting who can see your ads. Focus on:  

  • Geotargeting: Narrow down to specific cities or regions (e.g., “New York City, Los Angeles”) instead of broad countries. Fraudsters often target broad regions to avoid detection.
  • Device targeting: Prioritize devices your audience actually uses. For example, if you’re advertising a luxury app, focus on iOS and Android devices (not outdated Windows phones, which are common in bot networks).
  • IP filtering: Block data center IPs, VPNs, and IPs from high-fraud regions. Most ad platforms let you upload a list of blocked IPs—or use pre-built lists from verification tools.

Step 3: Set Up Fraud Alerts to Stay Ahead

Fraudsters adapt quickly, so you need to stay vigilant. Set up real-time alerts for suspicious activity, such as:  

  • CTR spikes above 2%.
  • Traffic from untargeted regions.
  • Session durations under 10 seconds.
  • Alerts let you act fast, e.g., pausing a campaign or blocking a fraudulent IP, before you lose hundreds (or thousands) of dollars.

Step 4: Audit Your Supply Partners (Publishers, SSPs)

Not all supply partners are equally vigilant about fraud. To audit partners:  

1. Ask for fraud reports:

Request monthly data on their fraud rates. If a publisher’s fraud rate is above 10%, drop them.

2. Check for IAB certification:

The IAB standards aim to keep industry practices consistent, improve user experience, protect brands, and make ad performance measurement more accurate. A big part of the IAB standards is two tools: Ads.txt (for websites) and App-ads.txt (for mobile apps). These tools list the authorized sellers of ad space for a domain or app. That’s why partners like publishers or ad platforms with Ads.txt or App-ads.txt certification are more trustworthy.

3. Test small first:

Before committing to a large budget with a new partner, run a small test campaign (e.g., $500) to check for fraud.

Step 5: Monitor Campaigns Ongoing (Don’t “Set It and Forget It”)

Ad fraud isn’t a one-time problem; it requires regular checks.

Every week:  

  • Review key metrics (CTR, viewability, conversions) for trends.
  • Check IP and device data to ensure traffic matches your targeting.
  • Update your blocked IP list with new high-risk addresses.

Every quarter:

  • Re-audit your supply partners (fraud rates change over time).
  • Test new verification tools to complement your existing setup.

GatherStar: Built to Protect Your Programmatic Campaigns

At GatherStar, we know ad fraud is a top concern for advertisers, and we’ve designed our programmatic platform to make fraud prevention simple. Our solution integrates real-time fraud detection, targeted filtering, and transparent reporting into one easy-to-use dashboard, so you don’t need technical expertise to protect your budget. We block known bot networks, verify domains to prevent spoofing, and send alerts for suspicious activity, all while keeping your campaigns running smoothly. With GatherStar, you can focus on what matters most: driving real results from your programmatic spend.  

Final Thoughts: Take Control of Your Programmatic Budget

Ad fraud is a big problem, but it’s not an unsolvable one. By understanding what ad fraud is, recognizing its red flags, and using the right tools, you can stop wasting budget on fake traffic and start investing in real engagement. The key is to be proactive: don’t wait for a campaign to tank before checking for fraud. Instead, set up alerts, audit partners, and use verification tools from day one.  

With the right strategy (and a platform like GatherStar), you can turn programmatic advertising from a “budget risk” into a growth driver. Your brand deserves to get every dollar’s worth of value from its ad spend, and now, you have the steps to make that happen.

If you’re looking to craft more effective, AI-driven ad experiences, start with GatherStar today. And if you want dedicated expert support to maximize your results, reach out to the GatherStar team to explore how we can help elevate your programmatic campaigns.