ユン ソクチャン

ユン ソクチャン

Offensive Web Security Researcher

Security Contributor of GitHub, Python, Django, FastAPI(Starlette), Apache Airflow, Ruby, Ruby-on-Rails, Java Spring

Education

2020年03月 - 2026年02月

コンピュータ工学科 卒業予定

キョンヒ大学

2017年07月 - 2018年05月

脆弱性分析トラック 修了

次世代セキュリティリーダー育成プログラム(Best of the Best)

2017年03月 - 2020年02月

ハッキング防御科 卒業

韓国デジタルメディア高等学校

Work Experience

2025年04月 - 現在 11 ヶ月

Security Researcher

Zellic.io USA

  • Web2システムおよびインフラのセキュリティ監査(Auditing)
    • SaaSプラットフォームや暗号資産取引所インフラなど、複雑なWeb2環境に対する深度なセキュリティ評価を実施
    • ビジネスロジックの脆弱性、Denial-of-service、SQL Injectionなどの高リスク脆弱性をホワイトボックス/グレーボックステストで特定
  • セキュリティコンサルティングおよびリスク管理
    • クライアントと直接連携し、ビジネス継続性とセキュリティのトレードオフを考慮した最適な対策を提案・協議
2025年07月 - 2026年02月 8 ヶ月

Security Team Member (Volunteer)

Airflow Security Team, Apache Software Foundation USA

  • Apache Airflowチームに報告された脆弱性のトリアージと評価
  • オープンソースコミュニティとのコラボレーション
  • ASF ガイドラインに従ってプロジェクトのセキュリティ態勢の維持
2025年03月 - 2026年02月 1 年

学部研究生

PWNLAB(慶熙大学システムセキュリティ研究室、指導教員:チャン・デヒ)

  • Samsung マルチクラウド統合セキュリティ検証ツール開発およびWebサービスのペネトレーションテスト
    • AWS、GCP、Azureのセキュリティコンプライアンス約260項目(IAM、Network、Container、Database、Storage、Monitoring、Loggingなど)を自動診断するIaCベースのスキャナーを実装(Python、FastAPI)
    • 大規模企業環境に適したAgentlessアーキテクチャおよびMulti-thread並列スキャンエンジンを設計し診断効率を最適化
    • Samsung保有のWebサービス19件を対象にブラックボックスペンテストを実施し、主要な脆弱性10件を特定 -- IDOR(不適切なデータアクセス)、ファイルアップロードフィルタのバイパス、XSSなど中程度の影響の脆弱性を発見し対策を提示
  • システムハッキングのウォーゲーム `pwnable.kr` のソースコード保守および機能開発(PHP)
2023年09月 - 2025年03月 1 年 6 ヶ月

OO部隊, OO兵

国防部傘下研究所

  • OO研究開発
2020年07月 - 2023年06月 3 年

R&D / 先制対応チーム, セキュリティエンジニア

スティリアン

  • ウェブ脆弱性診断
  • 教育システム(Cyber Drill System、Django + React)の開発およびCTF運営
  • 社内技術管理ツール、技術ブログ、デプロイシステムなどのインフラ開発および保守

CTF Awards

2025

サイバー攻撃防御大会

Finalist

一般部門

主催:韓国国家情報院

Team: 경희대미남해커들 (KHU's hansome hackers)

2025

DEF CON CTF 33

Finalist

主催:Nautilus Institute

Team: Cold Fusion

2024

🏆 ホワイトハットコンテスト

1st

勇士部門

主催:韓国国防部

Team: 키보드워리어플랫폼

韓国国防部長官賞

2023

CODEGATE

Finalist

大学部門

主催:科学技術情報通信部

Team: 경희대미남해커들 (KHU's hansome hackers)

2022

CODEGATE

Finalist

大学部門

主催:科学技術情報通信部

Team: 경희대미남해커들 (KHU's hansome hackers)

2022

🏆 サイバー攻撃防御大会

2nd

公共部門

主催:韓国国家情報院

Team: resilience

国家安全研究所長賞

2022

🏆 HACKTHEON SEJONG 全国大学生サイバーセキュリティ競技大会

6th

主催:世宗特別自治市

Team: 라임도둑 (Lime Thief)

国家安全研究所長賞

2021

🏆 サイバー攻撃防御大会

2nd

公共部門

主催:韓国国家情報院

Team: resilience

国家安全研究所長賞

2019

🏆 サイバー作戦競技大会

2nd

学生部門

主催:韓国国防部

Team: ユンソクチャンTV登録・高評価・通知設定まで

サイバー作戦司令官賞

2018

🏆 情報セキュリティ競技大会

1st

個人予選

主催:韓国教育部

ソウル女子大学総長賞

2018

🏆 情報セキュリティ競技大会

1st

団体本選

主催:韓国教育部

Team: ムンシウ1人チーム

韓国教育部長官賞

2017

🏆 情報セキュリティ競技大会

1st

団体本選

主催:韓国教育学術情報院

Team: 4-day exploit

韓国教育学術情報院長賞

Disclosed Vulnerabilities

Django Django 10 Apache Airflow Apache Airflow 3 NAVER NAVER 3 Ruby on Rails Ruby on Rails 2 Python Python 1 FastAPI / Starlette FastAPI / Starlette 1 Ruby Ruby 1 Java Spring Java Spring 1 GitHub GitHub 1
Python

CVE-2024-7592

Denial of Service
7.5 High

Quadratic complexity parsing cookies with backslashes

There is a LOW severity vulnerability affecting CPython, specifically the 'http.cookies' standard library module. When parsing cookies that contained backslashes for quoted characters in the cookie value, the parser would use an algorithm with quadratic complexity, resulting in excess CPU resources being used while parsing the value.

Django

CVE-2023-36053

Regular Expression Denial of Service
7.5 High

Potential regular expression denial of service vulnerability in EmailValidator/URLValidator

In Django 3.2 before 3.2.20, 4 before 4.1.10, and 4.2 before 4.2.3, EmailValidator and URLValidator are subject to a potential ReDoS (regular expression denial of service) attack via a very large number of domain name labels of emails and URLs.

Django

CVE-2024-24680

Denial of Service
7.5 High

Potential denial-of-service in intcomma template filter

An issue was discovered in Django 3.2 before 3.2.24, 4.2 before 4.2.10, and Django 5.0 before 5.0.2. The intcomma template filter was subject to a potential denial-of-service attack when used with very long strings.

Django

CVE-2024-27351

Regular Expression Denial of Service
5.3 Medium

Potential regular expression denial-of-service in django.utils.text.Truncator.words()

In Django 3.2 before 3.2.25, 4.2 before 4.2.11, and 5.0 before 5.0.3, the django.utils.text.Truncator.words() method (with html=True) and the truncatewords_html template filter are subject to a potential regular expression denial-of-service attack via a crafted string. NOTE: this issue exists because of an incomplete fix for CVE-2019-14232 and CVE-2023-43665.

Django

CVE-2024-21520

Cross-Site Scripting
6.1 Medium

Cross-Site Scripting (XSS) in browserable API of django-rest-framework

Versions of the package djangorestframework before 3.15.2 are vulnerable to Cross-site Scripting (XSS) via the break_long_headers template filter due to improper input sanitization before splitting and joining with <br> tags.

Django

CVE-2024-41991

Denial of Service
7.5 High

Potential denial-of-service vulnerability in django.utils.html.urlize() and AdminURLFieldWidget

An issue was discovered in Django 5.0 before 5.0.8 and 4.2 before 4.2.15. The urlize and urlizetrunc template filters, and the AdminURLFieldWidget widget, are subject to a potential denial-of-service attack via certain inputs with a very large number of Unicode characters.

Django

CVE-2024-53908

SQL Injection
9.8 Critical

Potential SQL injection in HasKey(lhs, rhs) on Oracle

An issue was discovered in Django 5.1 before 5.1.4, 5.0 before 5.0.10, and 4.2 before 4.2.17. Direct usage of the django.db.models.fields.json.HasKey lookup, when an Oracle database is used, is subject to SQL injection if untrusted data is used as an lhs value. (Applications that use the jsonfield.has_key lookup via __ are unaffected.)

Django

CVE-2025-48432

Log Injection
5.3 Medium

Potential log injection via unescaped request path

An issue was discovered in Django 5.2 before 5.2.3, 5.1 before 5.1.11, and 4.2 before 4.2.23. Internal HTTP response logging does not escape request.path, which allows remote attackers to potentially manipulate log output via crafted URLs. This may lead to log injection or forgery when logs are viewed in terminals or processed by external systems.

Django

CVE-2025-64458

Denial of Service
7.5 High

Potential denial-of-service vulnerability in HttpResponseRedirect and HttpResponsePermanentRedirect on Windows

NFKC normalization in Python is slow on Windows. As a consequence, django.http.HttpResponseRedirect, django.http.HttpResponsePermanentRedirect, and the shortcut django.shortcuts.redirect were subject to a potential denial-of-service attack via certain inputs with a very large number of Unicode characters.

Django

CVE-2025-64460

Denial of Service
7.5 High

Potential denial-of-service vulnerability in XML serializer text extraction

Algorithmic complexity in django.core.serializers.xml_serializer.getInnerText() allows a remote attacker to cause a potential denial-of-service attack triggering CPU and memory exhaustion via specially crafted XML input processed by the XML Deserializer.

Django

CVE-2026-1285

Denial of Service
7.5 High

Potential denial-of-service vulnerability in django.utils.text.Truncator HTML methods

django.utils.text.Truncator.chars() and Truncator.words() methods (with html=True) and the truncatechars_html and truncatewords_html template filters allow a remote attacker to cause a potential denial-of-service via crafted inputs containing a large number of unmatched HTML end tags.

FastAPI / Starlette

CVE-2025-62727

Denial of Service
7.5 High

Starlette vulnerable to O(n^2) DoS via Range header merging

An unauthenticated attacker can send a crafted HTTP Range header that triggers quadratic-time processing in Starlette's FileResponse Range parsing/merging logic. This enables CPU exhaustion per request, causing denial-of-service for endpoints serving files (e.g., StaticFiles or any use of FileResponse).

Apache Airflow

CVE-2024-39877

Code Execution
8.8 High

Apache Airflow: DAG Author Code Execution possibility in airflow-scheduler

Apache Airflow 2.4.0, and versions before 2.9.3, has a vulnerability that allows authenticated DAG authors to craft a doc_md parameter in a way that could execute arbitrary code in the scheduler context, which should be forbidden according to the Airflow Security model.

Apache Airflow

CVE-2024-39863

Cross-Site Scripting
5.4 Medium

Apache Airflow: Potential XSS Vulnerability

Apache Airflow versions before 2.9.3 have a vulnerability that allows an authenticated attacker to inject a malicious link when installing a provider.

Apache Airflow

CVE-2024-45034

Code Execution
8.8 High

Apache Airflow: Authenticated DAG authors could execute code on scheduler nodes

Apache Airflow versions before 2.10.1 have a vulnerability that allows DAG authors to add local settings to the DAG folder and get it executed by the scheduler, where the scheduler is not supposed to execute code submitted by the DAG author.

Ruby

CVE-2024-41123

Denial of Service
7.5 High

DoS vulnerabilities in REXML

The REXML gem before 3.3.2 has some DoS vulnerabilities when it parses an XML that has many specific characters such as whitespace character, >] and ]>.

Ruby on Rails

CVE-2024-47887

Regular Expression Denial of Service
6.0 Medium

Possible ReDoS vulnerability in HTTP Token authentication in Action Controller

There is a possible ReDoS vulnerability in Action Controller's HTTP Token authentication. For applications using HTTP Token authentication via authenticate_or_request_with_http_token or similar, a carefully crafted header may cause header parsing to take an unexpected amount of time, possibly resulting in a DoS vulnerability.

Ruby on Rails

CVE-2024-41128

Regular Expression Denial of Service
6.0 Medium

Possible ReDoS vulnerability in query parameter filtering in Action Dispatch

There is a possible ReDoS vulnerability in the query parameter filtering routines of Action Dispatch. Carefully crafted query parameters can cause query parameter filtering to take an unexpected amount of time, possibly resulting in a DoS vulnerability.

Java Spring

CVE-2024-38809

Denial of Service
5.3 Medium

Spring Framework DoS via conditional HTTP request

Applications that parse ETags from "If-Match" or "If-None-Match" request headers are vulnerable to DoS attack.

GitHub

HackerOne #2646500

Denial of Service

DoS Vulnerability in GitHub Enterprise

GitHub and GitHub Enterprise are vulnerable to a potential denial-of-service attack caused by a maliciously crafted HTTP request.

NAVER

NBB-1126

Stored XSS

Stored XSS

NAVER is vulnerable to a stored-xss caused by a crafted payload.

NAVER

NBB-1143

SQL Injection

SQL Injection

NAVER is vulnerable to a SQL injection caused by a crafted payload.

NAVER

NBB-1260

Stored XSS

Stored XSS

NAVER is vulnerable to a stored XSS caused by a crafted payload.

Talks

“ハッカーの観点から見たDjangoフレームワーク” (韓国語で発表)

PyCon KR 2024

2024

“DjangoフレームワークN-day脆弱性分析とセキュアコーディングガイド” (韓国語で発表)

CODEGATE 2023

2023

“Djangoフレームワーク1-day分析” (韓国語で発表)

第26回ハッキングキャンプ

2023

“モダンウェブサービスにおけるバグケースとセキュアコーディング” (韓国語で発表)

STEALIENセキュリティセミナー

2022

Blog Posts