The S-Unit expands pentesting and red teaming with infostealer data via Passguard

Infostealers: a growing risk for initial access

Stolen credentials play a significant role in cyberattacks. According to the IBM X-Force Threat Intelligence Index 2025, attackers used valid account credentials for initial access in 30% of the incident response cases analysed.

Infostealers are one of the ways this data ends up in attackers' hands. The malware steals data including login credentials, cookies and active session tokens. This information is then bundled into what are known as infostealer logs and can be traded via channels including dark web marketplaces and other criminal networks. Attackers can subsequently use the stolen data to gain access to corporate environments.

Marko van Zwam, Managing Director of The S-Unit, explains: "Preventing initial access is a crucial step in cybersecurity. Attackers are increasingly making use of access stolen via infostealers. With Passguard's intelligence, we can now also validate and simulate this form of initial access in a controlled way."

Infostealer data as part of offensive security

As part of the partnership, The S-Unit is adding Infostealer Credential Testing to its offensive security service offering. This makes it possible to investigate whether access to an organisation has been stolen by infostealers, and what an attacker could achieve with it in practice.

Tom Leijte, CEO of Passguard: "If you think like an attacker, you also have to be able to work with the access an attacker actually has. Stolen credentials and sessions are increasingly part of that. By combining our intelligence with The S-Unit's offensive security expertise, they can now factor that reality into penetration tests and red teaming."

An ethical approach as the foundation

Both parties' ethical approach also plays an important role in the partnership. Nick Bruinsma, Lead Red Teamer at The S-Unit: "Passguard operates on a fully ethical basis that aligns with our own strict boundaries. This allows us to help organisations mitigate this risk without compromising on our ethical standards."

About The S-Unit

The S-Unit is a Dutch cybersecurity company specialising in offensive security. Since 2014, its team of more than 25 certified security specialists has been helping organisations strengthen their digital resilience through services including penetration testing, red teaming, social engineering, strategic security advice and training. More information: https://the-s-unit.nl/.

About Passguard

Passguard is a Dutch dark web monitoring platform specialising in infostealer malware. The company monitors in real time for stolen login credentials, cookies and active session tokens, giving organisations early insight into compromised access. Passguard works with hundreds of organisations worldwide, including AFAS Software, Damen Shipyards and Royal FloraHolland. More information: passguard.com.