PlaidCTF writeup for Web-200: kpop (bad deserialization)

Hello again! This is my second writeup from PlaidCTF this past weekend! It's for the Web level called kpop, and is about how to shoot yourself in the foot by misusing serialization (download the files). There are at least three levels I either solved or worked on that involved serialization attacks (mtpox, reeekeeeeee, and this […]

PlaidCTF Web-150: mtpox (hash extension attack)

Hey folks, This is going to be my first of a couple writeups about this past weekend's CTF: PlaidCTF! My first writeup is for a 150-point Web level called mtpox. I chose this one to do first not only because it's the first level I completed, but also because the primary vulnerability was a hash […]

Ghost in the Shellcode: fuzzy (Pwnage 301)

Hey folks, It's a little bit late coming, but this is my writeup for the Fuzzy level from the Ghost in the Shellcode 2014 CTF! I kept putting off writing this, to the point where it became hard to just sit down and do it. But I really wanted to finish before PlaidCTF 2014, which […]

Ghost in the Shellcode: gitsmsg (Pwnage 299)

"It's Saturday night; I have no date, a 2L bottle of Shasta, and my all-rush mix tape. Let's rock!" ...that's what I said before I started gitsmsg. I then entered "Rush" into Pandora, and listened to a mix of Rush, Kansas, Queen, Billy Idol, and other 80's rock for the entire level. True story. Anyway, […]

Ghost in the Shellcode: TI-1337 (Pwnable 100)

Hey everybody, This past weekend was Shmoocon, and you know what that means—Ghost in the Shellcode! Most years I go to Shmoocon, but this year I couldn't attend, so I did the next best thing: competed in Ghost in the Shellcode! This year, our rag-tag band of misfits—that is, the team who purposely decided not […]

ropasaurusrex: a primer on return-oriented programming

One of the worst feelings when playing a capture-the-flag challenge is the hindsight problem. You spend a few hours on a level—nothing like the amount of time I spent on cnot, not by a fraction—and realize that it was actually pretty easy. But also a brainfuck. That's what ROP's all about, after all! Anyway, even […]

Epic “cnot” Writeup (highest value level from PlaidCTF)

When I was at Shmoocon, I saw a talk about how to write an effective capture-the-flag contest. One of their suggestions was to have a tar-pit challenge that would waste all the time of the best player, by giving him a complicated challenge he won't be able to resist. In my opinion, in PlaidCTF, I […]

A padding oracle example

Early last week, I posted a blog about padding oracle attacks. I explained them in detail, as simply as I could (without making diagrams, I suck at diagrams). I asked on Reddit about how I could make it easier to understand, and JoseJimeniz suggested working through an example. I thought that was a neat idea, […]

Padding oracle attacks: in depth

This post is about padding oracle vulnerabilities and the tool for attacking them - "Poracle" I'm officially releasing right now. You can grab the Poracle tool on Github! At my previous job — Tenable Network Security — one of the first tasks I ever had was to write a vulnerability check for MS10-070 — a […]

Everything you need to know about hash length extension attacks

You can grab the hash_extender tool on Github! (Administrative note: I'm no longer at Tenable! I left on good terms, and now I'm a consultant at Leviathan Security Group. Feel free to contact me if you need more information!) Awhile back, my friend @mogigoma and I were doing a capture-the-flag contest at https://stripe-ctf.com. One of […]

Using “Git Clone” to get Pwn3D

Hey everybody! While I was doing a pentest last month, I discovered an attack I didn't previously know, and I thought I'd share it. This may be a Christopher Columbus moment - discovering something that millions of people already knew about - but I found it pretty cool so now you get to hear about […]

Remote control manager FAIL

Hey guys, Today, I thought it'd be fun to take a good look at a serious flaw in some computer-management software. Basically, the software is designed for remotely controlling systems on networks (for installing updates or whatever). As far as I know, this vulnerability is currently unpatched; there are allegedly mitigations, but you have to […]

A deeper look at ms11-058

Hey everybody, Two weeks ago today, Microsoft released a bunch of bulletins for Patch Tuesday. One of them - ms11-058 - was rated critical and potentially exploitable. However, according to Microsoft, this is a simple integer overflow, leading to a huge memcpy leading to a DoS and nothing more. I disagree. Although I didn't find […]

(Mostly) good password resets

Hey everybody! This is part 3 to my 2-part series on password reset attacks (Part 1 / Part 2). Overall, I got awesome feedback on the first two parts, but I got the same question over and over: what's the RIGHT way to do this? So, here's the thing. I like to break stuff, but […]

Hacking crappy password resets (part 2)

Hey, In my last post, I showed how we could guess the output of a password-reset function with a million states. While doing research for that, I stumbled across some software that had a mere 16,000 states. I will show how to fully compromise this software package remotely using the password reset.

Hacking crappy password resets (part 1)

Greetings, all! This is part one of a two-part blog on password resets. For anybody who saw my talk (or watched the video) from Winnipeg Code Camp, some of this will be old news (but hopefully still interesting!) For this first part, I'm going to take a closer look at some very common (and very […]

Ethics of password cracking/dissemination

It's rare these days for me to write blogs that I have to put a lot of thought into. Most of my writing is technical, which comes pretty naturally, but I haven't written an argument since I minored in philosophy. So, if my old Ethics or Philosophy profs are reading this, I'm sorry!

Watch out for exim!

Hey everybody, Most of you have probably heard of the exim vulnerability this week. It has potential to be a nasty one, and my brain is stuffed with its inner workings right now so I want to post before I explode! First off, if you're concerned that you might have vulnerable hosts, I wrote a […]

Faking demos for fun and profit

This week Last week Earlier this month Last month Last year (if this intro doesn't work, I give up trying to post this :) ), I presented at B-Sides Ottawa, which was put on by Andrew Hay and others (and sorry I waited so long before posting this... I kept revising it and not publishing). […]

A call to arms! Web app fingerprints needed!

Hey all, This is partly an overview of a new Nmap feature that I'm excited about, but is mostly a call to arms. I don't have access to enterprise apps anymore, and I'm hoping you can all help me out by submitting fingerprints! Read on for more.