OneSpan - How to Protect eSignature Signing URLs and Prevent Cyberattacks

In a world where data breaches are increasingly common, organizations can no longer overlook security gaps in their digital processes. While IT and InfoSec teams focus on perimeter defenses and threat detection, one often-missed vulnerability can undermine the entire security posture — eSignature authentication.

Without robust signer authentication, companies risk losing their ability to prove who signed a document — jeopardizing legal enforceability and compliance. But that’s only part of the problem. Weak or missing authentication can also expose sensitive data within digital agreements, making them prime targets for cybercriminals.

The Hidden Risk in Signing URLs

eSignature workflows are now an integral part of modern business — from contract approvals and mortgage forms to insurance and account opening applications. These documents often contain personally identifiable information (PII) and other sensitive data that attackers can exploit for identity theft or social engineering.

The threat has evolved even further with AI-powered bots capable of scanning the internet for exposed signing URLs at scale. If your eSignature process doesn’t include authentication, unauthorized individuals could easily access confidential agreements.

What Are Signing URLs and Why Do They Matter?

When a document is ready for signature, an eSignature service generates a signing URL — a unique link sent to the intended signer via email or SMS. Depending on your scenario, the security of that link can vary:

• Internal (B2E) – Users sign documents through company VPN or Single Sign-On (SSO). Access is limited to internal networks and identity systems.
• Integrated B2C apps – The signing experience is embedded in a mobile or web app, and users authenticate before accessing it. In this case, URLs are not exposed publicly.
• Public links (most common) – Customers receive a direct signing URL via email or SMS. Without additional authentication, anyone with the link can access the documents — a serious security risk.

Because emails and SMS messages can be intercepted or scanned by gateways and filters, organizations must ensure that only verified recipients can open signing URLs.

The solution is simple: add signer authentication. Choose an authentication method that matches your compliance requirements and risk profile while maintaining a seamless user experience.

Best Practices for Signer Authentication

Effective eSignature security is about finding the right balance between user convenience and protection. Authentication should align with the risk level of each transaction — enhancing both completion rates and compliance.

OneSpan Sign: Flexible Authentication for Every Scenario

As a global leader in digital identity and eSignature security, OneSpan provides a broad range of authentication methods to ensure signer identity and transaction integrity. Organizations can choose a single option or layer multiple methods for stronger security:

• Security Questions (Q&A) – Signers must answer predefined challenge questions.
• Dynamic Knowledge-Based Authentication (KBA) – Integration with data providers like Lexis Nexis generates real-time, personalized questions that only the legitimate user can answer.
• SMS One-Time Password (OTP) – A verification code sent via text ensures only the recipient can access the document.
• Certificate-Based Authentication – Users authenticate with a trusted digital certificate and PIN, enabling qualified electronic signatures (QES).
• Government Credentials (CAC/PIV) – Multi-factor authentication using smart cards and PINs for government or regulated sectors.
• Digital Identity Verification – Scans and validates government-issued IDs and matches them with a real-time selfie.
• Hardware Security Tokens (Digipass®) – Time- or event-based passcodes for secure, token-based authentication.
• FIDO Passkeys – Modern, phishing-resistant authentication using mobile biometrics, providing seamless and secure signer verification.

How to Protect Your eSignature Signing URLs

In today’s threat landscape, neglecting signer authentication is no longer an option. Every exposed signing URL can become a gateway for attackers to access private data or impersonate legitimate users.

Whether you’re using automated workflows or sending one-time signature requests, enabling authentication is a simple yet powerful step toward protecting your organization’s:

• Sensitive data
• Legal integrity
• Customer trust
• Brand reputation

With OneSpan Sign, businesses can ensure that every digital signature is secure, compliant, and verifiable — building a stronger foundation for trust in digital transactions.

About Softprom

Softprom is an official distributor of OneSpan, delivering trusted eSignature, identity verification, and authentication solutions across Europe and CIS countries. Contact our team to learn how to enhance your organization’s digital transaction security with OneSpan Sign.