Artículo
mayo 16, 2025

/What is a Man-in-the-Middle (MITM) Attack and how to prevent it?

José Miguel Sánchez

Digital Identity consultant

From opening bank accounts to accessing government services, the ability to verify one’s identity securely and remotely has transformed modern life. But as technology has advanced, so too have the methods of cybercriminals. Among the most dangerous and difficult-to-detect threats to identity verification is the Man-in-the-Middle (MitM) attack: when a third party secretly intercepts the communication between two entities without their knowledge.

In the context of identity verification, this means an attacker could capture or alter biometric data—such as a selfie or voice recording—while it is being transmitted from the user’s device to the verification server.

According to Veridas, 3% of onboarding attempts across our clients are fraudulent. The average financial loss per fraud event is around €4,000 and can reach up to €11,000 in more complex cases.

This underscores the importance of implementing a robust fraud prevention solution to protect digital identity verification workflows against the entire spectrum of fraud.

The Spectrum of Attacks: Analog and Digital

Veridas classifies biometric fraud techniques into two broad categories: analog attacks and digital attacks, each with specific subtypes that target different stages of the verification process.

Analog Attacks

Analog attacks involve physical or visual deception in front of a camera. They include:

Presentation Attacks

Presentation Attacks refer to intentional attempts to deceive biometric systems by presenting forged or manipulated biometric evidence. These attacks are performed directly in front of a sensor, such as a camera, to trick the system into accepting a false identity.

Common examples include:

Printed photographs
Digital screens displaying another person’s face
High-quality silicone masks or 3D facial reconstructions

How to prevent them: The most effective countermeasure is the implementation of robust liveness detection techniques. These systems are designed to determine whether the biometric data originates from a real, live person, rather than a replica or static image.

Digital Attacks

Injection Attacks occur when attackers insert fake biometric data directly into the verification system, bypassing the camera or microphone. This is done through digital means, making it more difficult to detect with traditional liveness detection.

Common examples include:

Deepfake videos or pre-recorded clips streamed via virtual webcams
Emulators or debugging tools used to inject biometric content into the system

How to prevent them: Security teams should analyze user behavior for suspicious patterns and evaluate the software and hardware environment. This includes checking for virtual devices, emulator activity, and inconsistencies in device performance (e.g., unusual camera specifications).

Man-in-the-Middle (MitM) Attacks

This type of attack intercepts biometric data during transmission between the user and the verification server. The attacker positions themselves to capture or modify sensitive data before it reaches its destination.

How to prevent them: Implement end-to-end encryption and watermark the biometric evidence using secure capture SDKs to ensure data integrity and detect tampering.

What Is a Man-in-the-Middle Attack?

A Man-in-the-Middle attack occurs when a third party intercepts communication between two systems or individuals, unbeknownst to either of them. In the context of identity verification, this means an attacker could intercept or manipulate biometric data (like a selfie or voice sample) during its transmission between the user’s device and the verification server.

Real-World Risk in Identity Systems

Identity verification systems are especially vulnerable because they often:

Transmit sensitive personal and biometric data
Operate over potentially unsecured networks (e.g., public Wi-Fi)
Use mobile or web-based capture SDKs that could be manipulated in unsafe environments

Common Techniques Used in MitM Attacks

Common techniques used in MitM attacks include:

HTTPS Spoofing and SSL stripping
DNS spoofing to redirect traffic to malicious servers
Session hijacking by stealing authentication tokens
Rogue Wi-Fi hotspots that mimic legitimate networks

In identity verification, such exploits could allow attackers to alter ID photos, substitute biometric data, or hijack a verification session.

Why MitM Attacks Are Dangerous for Identity Verification

A successful MitM attack on an identity verification process could lead to:

Full impersonation of a legitimate user
Unauthorized account access
Fraudulent onboarding with stolen or synthetic identities
Reuse or manipulation of biometric evidence

This is especially critical in industries like:

Banking and fintech (e.g., account creation, transaction approval)
Telecommunications (e.g., SIM swaps)
Public administration (e.g., issuance of digital certificates)

Preventing Man-in-the-Middle Attacks: Best Practices

Veridas recommend layered defenses to prevent and detect MitM attacks. Here are essential security strategies tailored for identity verification platforms:

1. Implement End-to-End Encryption and Watermarking

Encrypt all biometric data transmissions using TLS 1.2+ and watermark the captured evidence (e.g., selfie, ID photo) using Veridas’ secure capture SDKs. This ensures that biometric data cannot be intercepted or altered undetected during transmission.

2. Use Secure Capture SDKs

Use certified and tamper-resistant SDKs for identity capture. Veridas SDKs are capable of:

Real-time glare and angle correction
Liveness detection at the point of capture
Detection of virtual cameras or emulators

3. Apply Real-Time Liveness Detection

Ensure that biometric input (selfie or voice) is coming from a real, live user. Veridas is one of the few vendors with iBeta ISO 30107-3 Level 2 certification for both active and passive liveness in web and native environments.

4. Detect Injection and Emulator-Based Attacks

Deploy backend logic to detect when data is injected using developer tools, virtual cameras, or emulated environments. Veridas’ backend services can flag these conditions and block the process immediately.

5. Avoid Public or Unsecured Networks

Educate users not to complete identity verification over public Wi-Fi or unknown networks. Combine with mobile app logic to flag risky environments.

How Veridas Protects Against MitM Attacks

Veridas employs a secure-by-design architecture, with multi-layered protections specifically tailored for identity workflows:

All identity processing is done in the back-end, avoiding execution on the client side where MitM attacks are easier.
TLS 1.2+ encryption, IP whitelisting, and API authentication protect data in transit.
Watermarked biometric evidence ensures data cannot be altered post-capture.
Injection attack detection blocks attempts to feed manipulated media into the system.
No data is stored unnecessarily, and biometric vectors are irreversible and non-interoperable.

Final Thoughts: Securing Identity in an Interceptable World

Man-in-the-Middle attacks remain a serious threat in digital identity systems, especially as fraudsters adopt advanced spoofing and interception techniques. Organizations must go beyond traditional HTTPS protections and implement identity-specific defenses like:

Backend-only processing
Real-time liveness and fraud detection
Watermarking of biometric captures
Secure SDKs with environmental checks

Solutions like those from Veridas are not only compliant with GDPR and the European AI Act, but they also represent a best-in-class defense model based on continuous innovation and trusted certifications.

FAQs: Man-in-the-Middle Attacks in Identity Verification

What is a Man-in-the-Middle attack in identity systems?

It’s an attack where someone intercepts communications between a user and a verification system, potentially altering or stealing biometric or identity data.