ABOUT / HANN

A closer
look.

I turn infrastructure and security that relied on people's memory into structures that code protects. Kim JunHyun / PUBLIC CLOUD INFRASTRUCTURE & SECURITY ENGINEER · 2020 — NOW

01 / MY ROLE

Assistant Manager · Cloud Security Engineer

Designed, built, and operated cloud security architecture for affiliates including Woori Bank, Woori Card, and Woori Financial Group, across a hybrid environment of public cloud, private cloud, and on-premises.

Main engineer in charge of design, build, operations, and incident response for multi-cloud game service infrastructure across 4 cloud service providers (CSPs): AWS, GCP, Azure, and Tencent.

Main engineer dedicated to game company clients at an Azure managed service provider (MSP), covering design, build, operations, security audits, and deployment automation.

02 / ACROSS

Three areas, worked on together

IaC automation

Define infrastructure as code with Terraform and Terragrunt

Multi-cloud operations

Design and operate 4 cloud providers together

Cloud security

Detection and response, least privilege, and audit response

03 / HOW I WORK

Principles from the job

01
Before adding a tool, see what the logs you already have can do.

In practice E2 · Stopping 3 a.m. DDoS attacks with no one on the keyboard ↗
02
Without authority, "I tried this and it got better" persuades more than "we should do this".

In practice E5 · From a monthly security review to a daily automatic one ↗
03
Stop at "no" and the conversation ends. Bring an alternative and things get fixed.

In practice E6 · Making sure the same finding never comes back ↗
04
When you move clouds, make the security standard move with you.

In practice E8 · Moving a live game between clouds without stopping it ↗
05
Put the rule in structure and code, and every deployment meets the same bar.

In practice E13 · Setting a security baseline for a financial cloud that had none ↗
06
Turning a control on is different from proving it stops the threat.

In practice E16 · "Turned on" and "actually blocking" are different things ↗
07
The requested fix ("please open it") and the real problem can differ. Check what is failing first.

In practice E17 · Operations tools that run on a PC with no internet ↗
08
AI supports the judgment. A person approves the action.

In practice P1 · A virtual company staffed by 11 AI employees ↗

04 / EXPERIENCE

EXPERIENCE.

Feb 2026 – Oct 2026
Woori FIS
Information Security Department · Assistant Manager · Cloud Security Engineer
- Designed and completed Woori Financial Group's first cloud security policy definition after joining, and distributed it to the group's affiliates
- Brought AWS Network Firewall, WAF, and Shield security infrastructure under code for the first time, in an environment with no Terraform
- Built a Python pipeline that automatically collects and analyzes network communication settings across multiple AWS accounts
- Integrated GuardDuty, Security Hub, WAF, Network Firewall, and Shield with a Splunk-based SIEM/SOAR
- Defined IAM permissions in Terraform to block excessive grants by design, following Zero Trust principles and the network separation (a Korean financial regulation) requirements in Korea's Electronic Financial Supervisory Regulations
- Operated hybrid security solutions together: FortiGate, NxPortrait, and WIPS
- Helped set security policy as an early member of public cloud adoption in the financial sector
Feb 2023 – Feb 2026
Com2us Platform
Infrastructure Technology Office, Cloud Division · Assistant Manager · Cloud Engineer
- Cut deployment time by 40% by moving from Terraform to Terragrunt
- Migrated from GCP to Tencent Cloud with zero downtime (80 servers and 20 databases, completed within one week)
- Raised CSPM (cloud security posture check) remediation from 60% to 85% or higher
- Cut DragonSky infrastructure costs by up to 62%
- Analyzed every cross-cloud firewall policy across Tencent and GCP, at 600 servers and 70 databases, then redesigned them
- Automated audits in Python that collect assets and audit logs from 4 CSPs into a common schema. Permission grants, Access Key issuance, and changes to key servers and databases trigger immediate Slack and Telegram alerts
- Handled audits across 4 CSPs: moved recurring findings into Terraform module defaults and mandatory validate and plan gates in CI/CD
- Ran unified alerting with Zabbix, Grafana, Slack, and Telegram, and DDoS defense with GCP Cloud Armor
Aug 2020 – Feb 2023
C&Thoth
Cloud Service Team · Associate to Assistant Manager · Cloud Engineer (Azure MSP)
- Ran Azure infrastructure for many game services in Korea and worldwide, including dedicated operations for MIR4 Global (3,500 servers and 650 databases)
- Automated DDoS detection and blocking with Azure Log Analytics and PowerShell
- Improved deployment speed by 80% with PowerShell deployment automation (MIR4 Korea)
- High-availability architecture on Dedicated Host, and real-time incident response
- Built real-time dashboards with Telegraf, InfluxDB, and Grafana (TIG stack)
- Handled client cloud security audits based on CSPM and ISMS (Korea's information security management certification)

EDUCATION

Mar 2015 – Feb 2020 Kyungmin University, Department of Information and Communication
Includes the military service period
Dec 2019 – Aug 2020 Bachelor's degree, Academic Credit Bank System (National Institute for Lifelong Education)
Degree conferred in Information and Communication

TRAINING · SERVICE

Feb 2020 – Jul 2020 KG ITBANK: AWS Architecture Design Specialist Training Program
6 months, 800 hours. Project: migrating a fictional client to AWS
Dec 2016 – Sep 2018 Military service (Republic of Korea Army, honorably discharged)
Sergeant. Signal soldier (switchboard operator)

CERTIFICATE

2021.08.18 NCP — Naver Cloud Platform Certified Professional
Valid
2021.07.07 NCA — Naver Cloud Platform Certified Associate
Valid
2021.06.02 Engineer Information Processing (Korean national certification)
Valid
2020.10.22 Microsoft Azure Fundamentals (AZ-900)
Valid
2019.10.11 Linux Master Level 2
Valid
2019.07.09 Network Administrator Level 2
Valid
2022.12.18 HashiCorp Certified: Terraform Associate
Expired
2022.12.16 CKA — Certified Kubernetes Administrator
Expired
2022.06.09 Microsoft Azure Database Administrator Associate
Expired
2022.06.08 Microsoft Azure Solutions Architect Expert
Expired
2022.06.07 Microsoft Azure Administrator Associate
Expired
2022.05.29 AWS Certified Solutions Architect – Professional
Expired
2021.07.01 Microsoft Azure Architect Technologies
Expired
2021.06.18 Microsoft Azure Security Engineer Associate
Expired
2020.06.23 AWS Certified Solutions Architect – Associate
Expired

PATH

2013 Volunteer work in Nepal
Joined "Precious Wings 2" (Seoul Metropolitan Mangwoo Youth Center) to help reinforce facilities at a local school, and also helped run its sports day.
2015 Enrolled at Kyungmin University, Information and Communication
Started learning networks and servers.
2016–2018 Military service (Republic of Korea Army, honorably discharged)
Served as a signal soldier (switchboard operator) and was discharged as a sergeant.
2020 Completed AWS training and earned a degree
Migrated a fictional client to AWS in KG ITBANK's 800-hour course, and earned a bachelor's degree through the Academic Credit Bank System.
2020 Joined C&Thoth
Started my career as an Azure MSP engineer, operating MIR4 Korea, ADT-CAPS, and others. As a dedicated cloud engineer for a game company, I took on infrastructure of up to 3,500 servers and 650 databases from the early design stage.
2023 Joined Com2us Platform
Began operating 4 clouds together: AWS, GCP, Azure, and Tencent. Hit Terraform's limits running many regions at scale, so I moved the structure to Terragrunt, and migrated to Tencent Cloud with no service interruption.
2026 Woori FIS, Information Security Department
In a financial security organization, I set up the group's first cloud security policy definition and put its security infrastructure into code for the first time.
2026.11 Next challenge
Looking for a team to join in a cloud infrastructure or security role.