Cossack Labs is a British company, headquartered in London, with R&D offices across Ukraine. We support innovators by protecting innovations. Our data security solutions assist businesses of all sizes and industries protecting their sensitive data against external attackers, insider threats, mis-configurations while remaining compliant with regulations.
5 жовтня 2026 бронювання

Junior Application Security Engineer

Київ, Львів, віддалено

This position is only for Ukrainian residents within Ukraine.

We are looking for a Junior Application Security Engineer. If you are interested in performing security assessments and working hand in hand with security engineers and software developers, this could be the position for you!

We are ready to invest time in your education if you are prepared to work diligently and responsibly. Alongside technical skills, we’ll teach you leadership, time management, business context, and how to keep improving cybersecurity despite the ever-increasing entropy of the world.

Responsibilities:

  • Perform security assessment and review of code and behaviour of systems (web, API, backends, Linux). Mostly whitebox, occasional blackbox.
  • Perform security search for weaknesses and vulnerabilities in software in novel fields and areas.
  • Participate in SSDLC for our products and our customers’ products. Explain risks & threats, work with developers to select security controls that would improve security without restricting usability/performance.
  • Dive into application security, infrastructure security, cloud and on-prem infrastructures, dedicated hardware, IoT security, ML security, and weird stuff beyond casual imagination with our team of skilled engineers. Check out an example of our work.
  • Stay updated with emerging security threats, vulnerabilities, and controls by reading articles, papers, and NIST guidelines. Follow CVE updates and understand how the threat landscape is changing.

Requirements:

  • 1+ years as an Application Security Engineer or similar position.
  • Experience in performing security assessment for web applications and cloud systems.
  • Be familiar with application security verification frameworks: OWASP ASVS.
  • Understanding SSDLC and its difficulties: OWASP SSDLC, NIST SSDF.
  • An overall understanding of what information security is, how real-world risks and threats affect the choice of security controls. How to combine detective, preventive and corrective controls.
  • Experience in popular security tools required for the job, or ability to learn them quickly (Burp Suite, network analysers, various SAST and DAST, dependency and vulnerability scanners).

Nice to have:

  • A certain area of expertise and deep interest in web, mobile, IoT, infrastructure — an area where you have “seen things” and ready to share experience.
  • Basic knowledge in cryptography: understanding the differences between symmetric and asymmetric cryptography, hashing, KDF.
  • Be familiar with NIST SP 800-53.
  • Be familiar with threat modelling (OWASP threat modelling, STRIDE, MITRE ATT&CK).
  • Practical experience in scripting languages (Python, Bash, or even Javascript (meh)).

Our hiring process:

  • Test task
  • Introduction call
  • Technical interview
  • Background check
  • Offer

What’s in it for you?

  • Competitive compensation with a flexible bonus scheme.
  • Hybrid work model: this position allows for a combination of in-office and remote work as needed.
  • UK, EU and USA clients.
  • Working at the crossroads of ML security, cryptographic protocol support, hardware protection, reverse-resilient mobile app development, and securing web apps for millions of users.
  • You will work with people deeply interested in security engineering, you will learn a lot.
  • Public track record in the open-source aspect of our products.
  • Conferences, books, courses — we encourage learning and sharing with the community. Our team members share a lot in talks, workshops, and blog posts.
  • Paid vacation — 21 business days per year.
  • Paid sick leaves.

Our software is well-known amongst security-aware teams, recommended by OWASP, and popular for easily solving complicated security challenges. Apart from building “off-the-shelf” solutions, we design custom security controls for novel problems. We work in the B2B space, with customers such as power grid operators, payment processors, legal companies, and million-user customer applications. We cater to young ambitious startups and well-established enterprises, that use our software and solutions as a core part of their security arsenal.

We are a data security solutions company, providing custom bespoke solutions to innovative software development teams around the world. Our software is well-known amongst security-aware teams, recommended by OWASP, and popular for easily solving complicated security challenges. Apart from building “off-the-shelf” solutions, we design custom security controls for novel problems.

We work in the B2B space, with customers such as IIoT, AI / ML based systems, mission critical systems, robotics, navigation, power grid operators, payment processors, financial apps, legal companies, million-user customer applications. We cater to young ambitious startups and well-established enterprises, who use our software and solutions as core part of their security arsenal. Our customers are smart, but extremely demanding.

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