Our business is securing yours

0x4A is a boutique IT security consultancy offering penetration testing, security assessments, and infrastructure and cloud architecture. We have extensive knowledge in securing cloud and infrastructure-as-code deployments.


Security challenges are rapidly changing due to market changes and transitions to the cloud. Let us help you assess your situation and protect you from increasingly complex cybersecurity threats.

Security Advisor

Take advantage of our years of experience as we help you establish a security plan from start to finish. We’ll also support you in maintaining a security culture, including setting goals, managing your threat model, examining risks, and creating incident response processes. Consider us your mentor, educator, or sounding board for all aspects of IT security.

Penetration Testing

Whether you’re in the private or public sector, we offer a wide variety of penetration tests ranging from classic web applications and network infrastructure to cloud deployments and ICS/SCADA systems. Our preference for white-box testing allows for comprehensive audits and a wide array of methodologies.

Security Assessment

Wherever you are in a project’s phase, assessing the situation at bird’s-eye level provides invaluable insight. We’ll identify any security gaps found between the current design and the expected outcome, and give you our analysis of how to proceed.

Cloud & Infrastructure Architecture

As infrastructure becomes more complex and reliant on third parties such as AWS, Azure, and Google Cloud Services, understanding all aspects of the security model is important for maintaining both reliable and secure networks. We’ll help you navigate the security pitfalls faced when designing, implementing, and maintaining modern and secure infrastructures.

Embedded Testing

IoT devices, implementations for routers and home optimization systems, and even toys – we provide thorough testing for your embedded device. Embedded testing is not only an effective way to reveal bugs and improve performance but also helps to reduce risk for the end user and can decrease your development costs.

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0x4A was founded by Jesper Larsson and is a result of his lifelong curiosity for complexity.

What began as an early interest in picking physical objects apart to see how they worked eventually led to tinkering with computer code, learning how to exploit vulnerabilities and even preventing them. It’d probably be no surprise to young Jesper that his grown-up self has been professionally active in the IT industry since 2003.

Jesper has been instrumental in implementing secure infrastructure solutions worldwide. In 2015, he co-founded a security consulting firm with an elite team of experts. In 2016, he joined penetration testing company Cure53 as a security and infrastructure specialist focusing on networks, VPNs, infrastructure, orchestrations, and deployment pipelines.

In the hopes of helping to make the Internet a better place, Jesper has audited numerous open source projects for a variety of nonprofits such as the Cloud Native Computing Foundation. He also co-founded Security Fest, an annual conference held in Gothenburg, Sweden, as a means to help spread industry knowledge. In his spare time, Jesper hosts and produces Säkerhetspodcasten, the first security podcast in Sweden.

Contact Us

For business enquiries please contact


PGP: 335B DD96 D578 7CA5 C710 B2FE 5DFB 9993 E45C B905

+46(0)735 24 32 07

0x4A SEC Holding AB

Hasthagsvagen 2
SE-433 30 Partille