Blacklist Fraud

What Is Blacklist Fraud?

Blacklist Fraud, also known as Blacklist-Related Fraud, refers to advertising traffic originating from infrastructure that has already been identified as malicious. This includes IP addresses, device identifiers, domains, subnets, proxies, or other digital assets that have previously been linked to fraudulent activity and recorded in fraud intelligence databases.

Rather than creating entirely new infrastructure, fraudsters frequently reuse compromised resources that have already participated in bot traffic, click fraud, fake installs, or other invalid traffic schemes. These assets often appear repeatedly across different campaigns, ad networks, and geographic regions.

According to FraudScore’s aggregated 2025 analysis, Blacklist Fraud became the largest identified fraud category, accounting for 37.29% of all detected fraudulent traffic, up from 28.84% in 2024. This trend highlights the growing reuse of known malicious infrastructure across the digital advertising ecosystem.

How Blacklist Fraud Works

Blacklist Fraud occurs when advertising traffic is generated through infrastructure that has already been identified as suspicious or fraudulent.

Common sources include:

• Compromised IP addresses previously involved in invalid traffic.
• Known proxy and VPN networks associated with fraud.
• Botnet infrastructure reused across multiple campaigns.
• Previously flagged devices with recurring fraudulent activity.
• Malicious domains and hosting providers linked to automated attacks.
• Residential proxy networks repeatedly used to disguise fraudulent traffic.

Fraud intelligence systems continuously update blacklists as new malicious infrastructure is identified. Incoming traffic is then compared against these databases to detect previously known fraud sources.

Why It Matters for Your Campaigns

Blacklist Fraud demonstrates that many attackers continue using infrastructure that has already been exposed in previous fraud investigations.

For advertisers, failing to identify this traffic can lead to:

• Advertising budgets being spent on known fraudulent sources.
• Reduced campaign quality and lower return on ad spend (ROAS).
• Increased exposure to bot traffic and invalid impressions.
• Distorted campaign analytics and attribution.
• Higher customer acquisition costs (CAC).
• Reduced trust in publisher and traffic source quality.
• Repeated fraud across multiple campaigns if compromised infrastructure is not blocked.

Because these threats are already known, they can often be prevented before they consume advertising budgets, making blacklist intelligence one of the fastest and most effective fraud detection mechanisms.

How to Prevent Blacklist Fraud

Preventing Blacklist Fraud requires continuously identifying and blocking traffic associated with known malicious infrastructure.

Recommended best practices include:

• Continuously update IP, device, and domain reputation databases.
• Block traffic originating from known malicious infrastructure before attribution.
• Combine blacklist intelligence with behavioral analysis and machine learning.
• Monitor repeated fraud patterns across campaigns and publishers.
• Analyze IP reputation together with device intelligence and network characteristics.
• Share threat intelligence across fraud detection systems whenever possible.
• Deploy real-time anti-fraud solutions capable of validating traffic before it reaches advertising platforms.

While blacklist filtering is highly effective against known threats, it delivers the strongest protection when combined with behavioral analytics, anomaly detection, and real-time fraud scoring to identify both known and previously unseen attacks.