Senior Mobile Security Engineer — Offensive iOS/Android

Klarna; City Of London; Hybrid; GBP 82,000 - 100,000; Full time

Job summary

Klarna is seeking an offensive mobile security specialist to test and harden its iOS and Android apps. You will reverse‑engineer binaries, identify sandboxing and permission weaknesses, and drive fixes with engineering teams.

You’ll work using OWASP MASVS/MASTG as your guide, with experience in Frida, MobSF, Burp Suite and related tools. A fintech security background is a bonus; hybrid work is common.

Qualifications

• Hands-on offensive mobile security work (pentesting, red-team, bug bounty) against iOS/Android.
• Understanding mobile internals: sandboxing, permissions, security architectures.
• Experience mapping security controls to MASVS/MASTG as the reference framework.

Responsibilities

• Perform offensive security assessments (pentests, red-team) against Klarna's mobile apps (iOS/Android).
• Reverse‑engineer app binaries to surface sandboxing, permission, and platform‑security weaknesses.
• Test apps against MASVS/MASTG and drive concrete fixes with engineering teams.
• Evaluate and stress‑test app‑hardening and RASP protections with developers.
• Document findings in actionable reports and ensure issues are fixed.

Skills

Offensive mobile security

Mobile app security

iOS security

Android security

Tools

Frida

Objection

MobSF

Jadx

apktool

Ghidra

Burp Suite

mitmproxy

Job description

Klarna is seeking an offensive mobile security specialist to test and harden its iOS and Android apps. You will reverse‑engineer binaries, identify sandboxing and permission weaknesses, and drive fixes with engineering teams.

You’ll work using OWASP MASVS/MASTG as your guide, with experience in Frida, MobSF, Burp Suite and related tools. A fintech security background is a bonus; hybrid work is common.