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Before yesterdayspaceraccoon.dev

Embedding Payloads and Bypassing Controls in Microsoft InfoPath

18 June 2022 at 10:00
While browsing a SharePoint instance recently, I came across an interesting URL. The page itself displayed a web form that submitted data to SharePoint. Intrigued by the .xsn extension, I downloaded the file and started investigating what turned out to be Microsoft InfoPath’s template format. Along the way, I discovered parts of the specification that enabled loading remote payloads, bypassing warning dialogs, and other interesting behaviour.

Solving DOM XSS Puzzles

3 February 2022 at 00:05
DOM-based Cross-site scripting (XSS) vulnerabilities rank as one of my favourite vulnerabilities to exploit. It’s a bit like solving a puzzle; sometimes you get a corner piece like $.html(), other times you have to rely on trial-and-error. I recently encountered two interesting postMessage DOM XSS vulnerabilities in bug bounty programs that scratched my puzzle-solving itch.

2Q21: New Year's Reflections

31 December 2021 at 10:24
Wishing you and your loved ones a very happy new year!

The InfoSecurity Challenge 2021 Full Writeup: Battle Royale for $30k

26 November 2021 at 03:32
From 29 October to 14 November 2021, the Centre for Strategic Infocomm Technologies (CSIT) ran The InfoSecurity Challenge (TISC), an individual competition consisting of 10 levels that tested participants’ cybersecurity and programming skills. I took away important lessons for both CTFs and day-to-day red teaming that I hope others will find useful as well. What distinguished TISC from typical CTFs was its dual emphasis on hacking AND programming - rather than exploiting a single vulnerability, I often needed to automate exploits thousands of times. You’ll see what I mean soon.

All Your (d)Base Are Belong To Us, Part 2: Code Execution in Microsoft Office (CVE-2021-38646)

22 October 2021 at 11:43
By searching for DBF-related vulnerabilities in Microsoft’s desktop database engines, I took one step towards the deep end of the fuzzing pool. I could no longer rely on source code review and dumb fuzzing; this time, I applied black-box coverage-based fuzzing with a dash of reverse engineering. My colleague Hui Yi has written several fantastic articles on fuzzing with WinAFL and DynamoRIO; I hope this article provides a practical application of those techniques to real vulnerabilities.

All Your (d)Base Are Belong To Us, Part 1: Code Execution in Apache OpenOffice (CVE-2021-33035)

29 September 2021 at 03:35
This two-part series will share how I got started in vulnerability research by discovering and exploiting code execution zero-days in office applications used by hundreds of millions of people. I will outline my approach to getting started in vulnerability research including dumb fuzzing, coverage-guided fuzzing, reverse engineering, and source code review. I will also discuss some management aspects of vulnerability research such as CVE assignment and responsible disclosure.

Down the Rabbit Hole: Unusual Applications of OpenAI in Cybersecurity Tooling

17 September 2021 at 13:16
Most research into the malicious applications of AI tends to focus on human factors (scamming, phishing, disinformation). There has been some discussion of AI-powered malware but this remains very much in the proof-of-concept stage. This is partly a function of the kinds of models available to researchers - generative models lend themselves easily to synthetic media, while language models are easily applied to phishing and fake news. But where do we go from these low-hanging fruits?

ROP and Roll: EXP-301 Offensive Security Exploit Developer (OSED) Review and Exam

23 June 2021 at 15:21
After clearing the OSEP at the end of February 2021, I took the 60-day EXP-301/OSED package from March to May 2021, and finally cleared the exam in mid-June. At the time of writing, this costs $1299. As my job role is pretty multi-disciplinary, I found it necessary to build up my exploit development skills and the OSED came at a right time.

Life's a Peach (Fuzzer): How to Build and Use GitLab's Open-Source Protocol Fuzzer

22 May 2021 at 03:08
The Peach protocol fuzzer was a well-known protocol fuzzer whose parent company – Peach Tech – was acquired by GitLab in 2020. This article aims to demonstrate an end-to-end application of Peach Fuzzer, from build to deployment.

Offensive Security Experienced Penetration Tester (OSEP) Review and Exam

11 March 2021 at 09:40
Overall, I felt that the OSEP was worth the price of admission given the sheer amount of content it throws at you, as well as the excellent labs that will solidify your learning-by-doing. Here’s my review along with some tips and tricks to maximize your OSEP experience.

Applying Offensive Reverse Engineering to Facebook Gameroom

2 February 2021 at 17:03
Late last year, I was invited to Facebook’s Bountycon event, which is an invitation-only application security conference with a live-hacking segment. Although participants could submit vulnerabilities for any Facebook asset, Facebook invited us to focus on Facebook Gaming. Having previously tested Facebook’s assets, I knew it was going to be a tough challenge.

Supply Chain Pollution: Hunting a 16 Million Download/Week npm Package Vulnerability for a CTF Challenge

23 December 2020 at 15:29
GovTech’s Cyber Security Group recently organised the STACK the Flags Cybersecurity Capture-the-Flag (CTF) competition from 4th to 6th December 2020. For the web domain, my team wanted to build challenges that addressed real-world issues we have encountered during penetration testing of government web applications and commercial off-the-shelf products.

Imposter Alert: Extracting and Reversing Metasploit Payloads (Flare-On 2020 Challenge 7)

3 December 2020 at 13:04
I recently participated in FireEye’s seventh annual Flare-On Challenge, a reverse engineering and malware analysis Capture The Flag (CTF) competition. Out of the 11 challenges ranging from typical executables to games written in exotic programming languages, I liked Challenge 7 the best.

Beat The Clock: The CSIT InfoSecurity Challenge

18 September 2020 at 03:44
Last month, the Centre for Strategic Infocomm Technologies (CSIT) invited local cybersecurity enthusiasts to tackle the InfoSecurity Challenge (TISC). The Challenge was organized in a capture-the-flag format, with 6 cybersecurity and programming challenges of increasing difficulty unlocked one after another.

Open Sesame: Escalating Open Redirect to RCE with Electron Code Review

14 August 2020 at 11:43
This blog post will go through my whitebox review of an unnamed Electron application from a bug bounty program. I will demonstrate how I escalated an open redirect into remote code execution with the help of some debugging. Code samples have been modified and anonymized.

Closing the Loop: Practical Attacks and Defences for GraphQL APIs

15 May 2020 at 13:37
While GraphQL promised greater flexibility and power over traditional REST APIs, GraphQL could potentially increase the attack surface for access control vulnerabilities. Developers should look out for these issues when implementing GraphQL APIs and rely on secure defaults in production. At the same time, security researchers should pay attention to these weak spots when testing GraphQL APIs for vulnerabilities.

Same Same But Different: Discovering SQL Injections Incrementally with Isomorphic SQL Statements

5 April 2020 at 09:04
Despite the increased adoption of Object-Relational Mapping (ORM) libraries and prepared SQL statements, SQL injections continue to turn up in modern applications. In real-world scenarios, researchers need to balance two concerns when searching for SQL injections - 1. Ability to execute injections in multiple contexts; and 2. Ability to bypass WAFs and sanitization steps. A researcher can resolve this efficiently with something I call Isomorphic SQL Statements.

A Tale of Two Formats: Exploiting Insecure XML and ZIP File Parsers to Create a Web Shell

18 February 2020 at 06:02
While researching a bug bounty target, I came across a web application that processed a custom file type which was actually just a ZIP file that contains an XML that functions as a manifest. If handled naively, this packaging pattern creates additional security issues. These β€œvulnerabilities” are actually features built into the XML and ZIP formats. Responsibility falls onto XML and ZIP parsers to handle these features safely. Unfortunately, this rarely happens, especially when developers simply use the default settings.

Remote Code Execution in Three Acts: Chaining Exposed Actuators and H2 Database Aliases in Spring Boot 2

12 January 2020 at 23:15
The Spring Boot framework is one of the most popular Java-based microservice frameworks that helps developers quickly and easily deploy Java applications. With its focus on developer-friendly tools and configurations, Spring Boot accelerates the development process. However, these development defaults can become dangerous in the hands of inexperienced developers.