Guided Access Mode Bypass

As a penetration tester who specialises in mobile apps, I get good visibility of how the enterprise is adopting/using/misusing various iOS capabilities and MDM features. One trend I’ve seen increasingly, is the use of ‘Guided Access Mode‘ to lock down devices.

Guided-Access Mode (GAM), for the unfamiliar, locks the device into a single app. It’s typically considered a handy feature for parental guidance, but the official documentation also suggests its effectively the same as the more enterprisey ‘Single App Mode‘; which is true. ‘Single App Mode’ (SAM) does exactly the same thing, but can only be enabled via MDM on a device which is in ‘Supervised’ mode. So it makes sense that organisations which cant easily manage devices use GAM instead. Although many just don’t know that Single App Mode exists.

I’ve seen GAM in the medical, financial, industrial, and retail sectors now. I know that it’s being used to protect highly sensitive data from prying eyes and, in certain scenarios (industrial), I would not be surprised to hear that GAM is defending against life-threatening incidents. That’s a lot of pressure for a parental guidance feature.

I recently performed a penetration test for a prototype self-checkout kiosk/POS solution which used an iPad as the kiosk’s display. Long story short, the solution used Guided Access Mode and, yet again, I was foiled in my attempts to get around it.¬†The test finished a few weeks ago and, not one to give up, i’ve been testing Guided Access mode in my own time. Here’s the bypass ūüėČ:

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Kinda LIKE SQL Injection

TLDR: This post is about some late 90’s level hacking. But the fact is, that there just doesn’t exist a decent explanation of this vulnerability anywhere on the internet.. and yesterday, in 2018, I found another application vulnerable to it (to quite serious effect). I’m afraid that was the straw that broke the camel’s back. So now we’re doing this… we’re making the blog-post that should have been made 20 years ago. There is a simple zipped-up MySQL/PHP lab at the bottom of this post, feel free to skip to that if you are so inclined.

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The Happn’ing

Years ago, one of the first posts I ever wrote was about my experience scripting a bot for the dating site OKCupid. It was just a PoC bashed together over a few beers with a friend.
Since then (and becoming single) I’ve scripted bits and bobs¬†for virtually every major dating site/app… its become a bit of a weird hobby.
A while ago I wrote a reasonably feature-filled script¬†for managing a user account on the dating app Happn,¬†imaginatively called¬†Happn.py”.¬†It was immediately spotted by a few Happn employees on my github, who starred the project, but then prevented it from actually working by blocking the python user-agent on the Happn servers. I made the repo¬†private and updated it to work again, with the intention of spending some more time developing it. That time never really came and I stopped using Happn a while ago, so I made the tool public and this is just a quick post to share it.

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SQL Injection using System Variables in MySQL

For¬†BSides Manchester 2015, the UK pen-testing company aptly named ‘Pentest Ltd’ held a SQL injection challenge where the injection point required structuring¬†the payload in a specific manner with MySQL voodoo to keep the payload under 90 characters, and bypass a basic WAF.
I was fairly certain the lab could also be accomplished using MySQL variables, but was unable to get the job done. Low and behold, it totally was possible and it turned out I overcomplicated the solution which they revealed could be achieved with the following:

This was something I’d never looked at before, and it just¬†didn’t cross my mind to store the query result and retrieve¬†it using¬†a variable with¬†one hit using a UNION. I was trying to do this over two queries and therefore¬†my variable would always be empty/null when i tried to retrieve it, as MySQL variables are scoped to a SESSION ( a single database connection ), and are emptied after the first query completes and the application closes its connection.
This lead me to going completely down the wrong rabbit hole trying to solve the challenge, but also into discovering something reasonably interesting:¬†SQLi¬†with System Variables. Continue Reading “SQL Injection using System Variables in MySQL”

"Bypassing" CSP’s Data-Exfiltration Protections

A long time ago now, I tweeted a challenge to see of anyone knew what the following URL would attempt to do:

Don’t worry, I don’t expect you to stare at that monstrosity. Instead I’ll just tell you;
So a friend of mine was competing in¬†WhiteHatRally¬†last year, which is a sort of “solve the clues to figure out where to go”-style car race for charity, and he realised that it might be possible to stalk the other competitors, who were displaying there progress on FB¬†via¬†GPS tracking site insta-mapper.com, in order to determine where they were going and beat them there. So initially we looked at spending a weekend¬†making an app to cheat at a charity race by scraping the other contestant’s locations in semi-real-time… we’re that cool. But I ended up spending the weekend learning the ins and outs of Content Security Policy (CSP) instead, which actually is quite cool. In this post I’ll explain what a learned about CSP that stopped our attack, and how we were still able to ‘bypass’ it and skin the cat a different way. Continue Reading “"Bypassing" CSP’s Data-Exfiltration Protections”