AppGreat is one of the fastest growing global IT companies, supporting the highest tech organizations in the world with 6 offices: 1 in Sofia, 1 in Skopje, 1 in Bucharest, 1 in Tel Aviv, 1 in Chisinau and 1 in Warsaw.

We are working with top talents and highly experienced management to ensure the world's leading technology companies meet all the business challenges that the future holds.

We are AppGreat! We are a young and ambitious company like no other!

WHY JOIN OUR DREAM TEAM?

The most important part of AppGreat is the team. From our founders to the last person, we are committed to creating a pleasant environment and a place where everybody feels like they belong.

We invest in them in any way we can, starting from the amazing atmosphere in the office, unique benefits and career growth opportunities.

We are seeking an experienced Windows Kernel Driver Specialist to join our team, responsible for developing advanced collection, prevention, and protection technologies. This role involves utilizing both documented and undocumented proprietary kernel mode techniques.

We are an endpoint security company looking for an expert-level Windows Kernel Driver Specialist to assist our engineering team in resolving a critical stability issue. Our Endpoint Detection and Response (EDR) agent is currently experiencing sporadic Blue Screen of Death (BSOD) crashes in the field.

We need an experienced debugger - someone who lives in WinDbg, understands the Windows Memory Manager inside out, and has specific experience improving the stability of file system minifilters and callback-heavy security drivers.

YOUR MISSION:

• Crash Dump Analysis: Perform deep-dive analysis of kernel memory dumps (Minidumps and Complete Memory Dumps) to identify the root cause of the crash (e.g., race conditions, stack overflows, invalid memory access, IRQL violations).
• Reproduction & Isolation: Design stress tests and verification procedures to reliably reproduce the BSOD in a controlled environment using tools like Driver Verifier and specific load-testing scripts.
• Code Review & Remediation: Audit the existing C/C++ driver code (specifically Minifilter callbacks and process notification routines) for thread safety, proper lock usage (Spinlocks/ERESOURCE), and memory handling.
• Patch Implementation: Implement robust fixes for the identified issues, ensuring zero regression in driver performance or security efficacy.
• Validation: Verify fixes using Microsoft Driver Verifier and HLK (Hardware Lab Kit) basics to ensure stability under high stress.

WHAT YOU WILL BRING TO THE COMPANY:

• Bachelor’s degree in Data Science, Computer Science, or related degree;
• C/C++: 3+ years of experience in strictly kernel-mode software development.
• WinDbg Mastery: Ability to perform "post-mortem" debugging without symbols for third-party conflicts, and live kernel debugging using VMWare/Hyper-V/KDNET. You must be comfortable analyzing stack traces, register states, and trap frames.
• Windows Internal Knowledge: Deep understanding of: IRQLs (Interrupt Request Levels) and DPC/Dispatcher mechanics, Memory Management (Paged vs. Non-Paged pool, MDLs), Synchronization primitives (Spinlocks, Mutexes, Pushlocks),
• File System Filters: Proven experience with the Filter Manager Model (FltMgr) and Minifilter drivers (FltRegisterFilter, Pre/Post operation callbacks).
• EDR/Security Driver Experience: Familiarity with: ObCallbacks (ObRegisterCallbacks), Process/Thread/Image Load Notify routines (PsSetCreateProcessNotifyRoutineEx, etc.), Avoiding deadlocks when injecting logic into high-frequency system paths.

NICE TO HAVE/ADVANTAGE:

• Reverse Engineering: Proficiency with IDA Pro or Ghidra to analyze potential conflicts with third-party drivers (e.g., Antivirus conflicts causing the crash).
• x64 Assembly: Ability to read disassembly to pinpoint the exact instruction causing the fault when source lines are ambiguous.
• WHQL/WHCP: Experience with the Windows Hardware Compatibility Program signing process (in case the fix requires re-certification).

OUR COMMITMENT TO YOU:

• Attractive remuneration package.
• Working style - Remote
• Flexible Working Hours: We care about results, not when you clock in, depending on the team working schedule.
• Team Events & Offsites: Regular team buildings and company events to keep the good vibes going.
• Learning & Development: Access to training programs to boost your skills and career.
• Career Growth Opportunities: Grow with a fast-scaling, innovation-driven company.
• Supportive Culture: Work with a young, motivated, and close-knit team.

We believe great work starts with great people. If this feels like the right place for you, we’d love to connect.

@Appgreat we appreciate every application we receive. Please note that only candidates selected for the next stage of the recruitment process will be contacted. If your profile matches the role, our Talent Acquisition team will reach out to you directly.

Thank you for your interest in joining us, and we encourage you to stay connected through our LinkedIn and Career pages for future opportunities and insights from the IT market.

Group: IT Jobs In Bulgaria – Remote Hybrid and On-Side

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