Senior Information Security Engineer, Application Security

Hexens

full-time

Posted on: 9/20/2025

Origin: • 🇬🇧 United Kingdom

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Senior

AndroidCloudGoiOSJavaJavaScriptPythonRustTypeScriptWeb3

About the role

Alongside our off-chain security lead, plan and deliver advanced application security assessments against API services, application front-ends, wallet software, browser plugins, mobile apps, and SDKs.
Collaborate with leading smart contract auditors and cryptography researchers, leveraging your application security expertise to assess attack surfaces outside their on-chain specializations.
Work to identify technical vulnerabilities, architectural flaws, and ways to mitigate future risk in the crucial junctions between off-chain and on-chain systems.
Interact with developers and key stakeholders when identifying and handling security issues.
Deliver clear and concise reporting on issues and attack paths identified.

At least 5 years experience, or equivalent technical expertise, delivering offensive security services, with a primary focus on application security.
Expert-level web application and API security experience, with proficiency assessing apps with modern web frameworks, and identifying advanced client-side, back-end, and business logic attacks.
Experience assessing mobile applications (Android/iOS), browser extensions, and desktop applications.
Practical experience finding complex vulnerabilities and attack paths in Golang, Rust, TS/JS, Python, Java, or C-based codebases during white/grey-box appsec assessments.
Working knowledge of cloud, CI/CD, container, CDN, and network security concepts, and how they apply to application security.
Knowledge or willingness to learn web3 security concepts and how they apply to web3-centric applications.
Decent scripting and automation skills.
Assisting with scoping requirements for application security work.
Strong client-facing and soft skills.
Big plus if any of the following apply: Significant web2 bug bounty/vulnerability disclosure history; Prior experience as a smart contract auditor or onchain-focused security researcher; Prior experience developing or integrating DeFi protocols, smart contracts, wallet services, or other web3 services; Advanced relevant security certifications (OSWE, Burp Suite Certified Professional, etc.)