With the growing digitalisation of data, document management has become a core activity in many organisations. However, the exchange of sensitive information between users and digital document management platforms makes them an attractive target for cybercriminals. One of the most frequent and dangerous threats is the Man-in-the-Middle (MitM) attack. This type of attack involves intercepting communications between two parties, allowing an attacker to read, modify or even inject malicious data without either party noticing. For companies that depend on data security, it is therefore essential to understand Man-in-the-Middle attacks and implement robust protection measures.
What is a Man-in-the-Middle (MitM) attack?
Definition and how it works
A Man-in-the-Middle (MitM) attack is a cyberattack technique in which the attacker secretly positions themselves between two parties who are communicating. The attacker can intercept, monitor and manipulate the communication without the parties involved noticing. This attack can occur in a variety of situations, such as on unsecured public Wi-Fi networks, poorly configured VPN connections or through malware installed on one of the users’ devices.
Stages of a Man-in-the-Middle attack
A Man-in-the-Middle attack is usually carried out in two phases. First, the attacker compromises the communication between users, that is, they establish a connection with both parties and lead them to believe they are communicating directly with each other. Next, they can eavesdrop on or alter the messages exchanged.
Types of Man-in-the-Middle attacks
Attacks on public Wi-Fi networks
This is one of the most common scenarios for MitM attacks. Public Wi-Fi networks are often unprotected, which makes it easier for attackers to intercept data. In these situations, users are often transferring important and sensitive data without adequate protection, which makes them easy targets.
DNS spoofing attacks
In DNS spoofing attacks, the attacker alters DNS records, redirecting users to fake websites without their knowledge. When users enter confidential information on these spoofed websites, the attacker collects the data with no difficulty at all.
HTTPS spoofing attacks
HTTPS is normally a secure form of communication, but in MitM attacks the attacker can create a fake HTTPS connection, deceiving users with fraudulent digital certificates. Although modern browsers include warnings for insecure certificates, less attentive users can easily fall into this trap.
How to prevent Man-in-the-Middle attacks on document management platforms
Implementing HTTPS and SSL/TLS certificates
One of the first lines of defence against MitM attacks is the use of SSL/TLS certificates. Indeed, these certificates ensure that communication between the server and the user is encrypted and authenticated. Document management platforms must make sure they use HTTPS to protect all data transfers. In addition, mechanisms such as HSTS force the browser to always use encrypted connections with the site, which prevents attempts to redirect users to unencrypted versions.
End-to-end encryption
End-to-end encryption is a fundamental technique for ensuring that only authorised recipients can access the information transmitted. Even if an attacker intercepts the communication, encryption prevents them from deciphering the data, making it useless to any cybercriminal. Document management platforms should therefore implement robust encryption solutions to protect sensitive data, both in transit and at rest.
Using virtual private networks (VPN)
Using virtual private networks (VPN) is another effective measure against MitM attacks. VPNs create a secure “tunnel” for communications, protecting the data being transmitted. This is particularly important when users need to access document management platforms over public or unsecured networks. However, the VPN must be trustworthy and properly configured; otherwise, it can become an attack vector.
Two-factor authentication (2FA)
Two-factor authentication (2FA) adds an extra layer of security by requiring users to verify their identity with a second authentication factor, such as a text message or a mobile app. Even if an attacker manages to compromise a user’s credentials through a MitM attack, they will find it much harder to get past the second layer of verification.
Continuous monitoring and intrusion detection systems
Continuous monitoring of network traffic and the use of intrusion detection systems (IDS) can help identify anomalous activity, such as the presence of attackers on a network. These systems can thus detect behaviour patterns that indicate a MitM attack and alert the security team before data is compromised.
DNS validation with DNSSEC
To prevent DNS spoofing attacks, organisations can implement DNSSEC (Domain Name System Security Extensions), which validates the authenticity of DNS responses. By implementing DNSSEC, document management platforms help ensure that users are accessing the correct site and not a spoofed website.
Challenges in preventing Man-in-the-Middle attacks
Complexity of implementing security measures
Protecting against MitM attacks may require several security measures, from end-to-end encryption to the use of VPNs and SSL certificates. This complexity can therefore be a challenge for small and medium-sized enterprises that lack specialist cybersecurity resources. Nevertheless, adopting basic measures, such as HTTPS and two-factor authentication, already provides a substantial layer of protection.
The constant evolution of threats
Cybercriminals are constantly refining their techniques and developing new ways to carry out MitM attacks. Protecting against this type of attack requires a proactive cybersecurity stance, with regular updates to security systems and ongoing training to help employees recognise potential warning signs.
Adversary-in-the-middle attacks and phishing-resistant authentication
In recent years, attacks in which the criminal places an intermediary site between the user and the real platform have become common. This technique, known as adversary-in-the-middle, makes it possible to capture the password and the authentication code sent by SMS or generated by an app in real time. As a result, traditional two-factor authentication is no longer enough in every scenario.
The answer lies in phishing-resistant methods, such as FIDO2 security keys or passkeys. These methods only work on the platform’s legitimate domain. Therefore, even if the user is tricked into visiting a fake site, authentication fails and the attacker does not gain access.
Practical example: A stolen session on a document platform
Imagine an administrator of a document management platform who receives an email asking them to confirm an urgent document. The link opens a page identical to the platform’s. The administrator enters their password and authentication code. Within seconds, the attacker uses these details to open a genuine session.
If the company has access monitoring, the system detects a login from an unusual location and locks the account. Moreover, had the administrator used a security key, the attack would not even have been possible. In this way, combining phishing-resistant authentication with monitoring greatly reduces the impact of these attacks.
Good practices for users
Technology greatly reduces the risk, but users remain an important line of defence. It is therefore worth remembering a few simple rules: access platforms through bookmarks rather than links received by email, never ignore certificate warnings and avoid public networks without a VPN. In addition, users should log out of shared devices and report any unexpected authentication request. In this way, the organisation combines technical measures with safe behaviour.
Frequently asked questions
How can I tell if I am the victim of a Man-in-the-Middle attack?
Some signs include invalid certificate warnings, login pages that appear for no reason or connections that switch from HTTPS to HTTP. In these cases, disconnect and inform the IT team.
Do passkeys work on document management platforms?
It depends on the platform. However, more and more providers support FIDO2 authentication, so it is worth including this requirement when choosing new solutions.
Does a VPN protect against all Man-in-the-Middle attacks?
No. A VPN protects traffic between the device and the VPN server, but it does not stop the user from being tricked by a fake site. It should therefore be combined with strong authentication and attention to the addresses visited.
Conclusion: Protection against Man-in-the-Middle attacks
Man-in-the-Middle attacks are one of the main threats to document management platforms, compromising data privacy and integrity. However, by implementing robust security measures, such as encryption, HTTPS, VPNs and two-factor authentication, companies can protect themselves effectively against these threats. Ultimately, the key to protection lies in a proactive and integrated security approach that combines advanced technology with ongoing employee training. For document management companies, investing in protection against MitM attacks means investing in the trust and security of their users.
Read also: Attacks on public Wi-Fi networks: Risks and how to protect yourself and DNS spoofing attacks: A silent threat to the integrity of your data.
For further cybersecurity recommendations, see the Portuguese National Cybersecurity Centre (CNCS).