Summary This blog post describes a GateKeeper bypass that worked on M1 Macs. With a few clicks in a web browser, the attacker could have executed malicious code on the victims’ machines. Introduction When the first M1 Macs appeared in the Apple Store, I immediately bought one. I was really excited to verify the attack vectors I thought about. I noticed that M1 Macs could install iOS apps compiled for ARM64, so maybe there will be inconsistencies?
Introduction I personally love vulnerabilities with stories. This one is of that kind… About one year ago, I submitted a vulnerability to Apple that they were unable to reproduce. We exchanged some emails with the clarifications, but the security team still couldn’t have validated the original vulnerability. Then they asked me to run sysdiagnose in order to collect logs that could have helped them. The problem Like a real security researcher I checked how the /usr/bin/sysdiagnose acutally works.
Summary This story is about an issue I reported in July of 2019 via Bugzilla. The ticket is public from the 16th of January 2020, so I don’t disclose any new vulnerability. However, I think such posts are necessary to show the community how applications installed on Macs may harm their privacy. This post will show you how an attacker that achieves code execution on your machine may use Firefox to abuse your Privacy preferences (TCC) and thus access your microphone/camera/location and record your screen.
Recently I read a really good book about macOS #appsec - Professional Cocoa Application Security. It’s from 2010 but still worth reading as the main concepts didn’t change so much. In this blog post, I’d like to share an interesting story that led to the discovery of CVE-2021-3162 - a local privilege escalation vulnerability in Docker on macOS. In Chapter 10 - “Deploying Software Securely”, I stumbled across configuring XPC services installers.
The new macOS Big Sur changed a lot of things and introduced new mechanisms. One of the biggest changes was deprecating kernel extensions that, among others, allowed a comprehensive way to filter network traffic. Basing on Network Kernel Extensions, firewall developers were able to code their products. On Big Sur, firewalls should be made using the Network Extension Framework. Unfortunately, as it turned out, Apple created an allowlist of their apps that legitimately bypass any filter you set using your firewall.
Storing secrets on the macOS is a big challenge and can be done in multiple insecure ways. I tested many mac apps during bug bounty assessments and observed that developers tend to place secrets in preferences or even hidden flat files. The problem with that approach is that any non-sandboxed application running with typical permissions can access the confidential data. For example, Signal on macOS stores a key that encrypts all your messages database in ~/Library/Application Support/Signal/config.
XPC Exploitation series Learn XPC exploitation - Part 1: Broken cryptography Learn XPC exploitation - Part 2: Say no to the PID! Learn XPC exploitation - Part 3: Code injections Intro The last technique I showed in my presentation during Objective by the Sea v3 conference was abusing privileged XPC services using different code injections. In many apps I exploited, I observed that developers are aware that privileged XPC services have to verify incoming connections.
XPC Exploitation series Learn XPC exploitation - Part 1: Broken cryptography Learn XPC exploitation - Part 2: Say no to the PID! Learn XPC exploitation - Part 3: Code injections Intro Hey! In my last post, I showed you how weak SecRequirement string might lead to incoming connections validation issues. This post will focus on another way to trick XPC servers into trusting our malicious process. 😈 We’re going to exploit a vulnerability that I found some time ago in Malwarebytes.
XPC Exploitation series Learn XPC exploitation - Part 1: Broken cryptography Learn XPC exploitation - Part 2: Say no to the PID! Learn XPC exploitation - Part 3: Code injections After my talk on Objective by the Sea v3 I received a lot of questions regarding XPC exploitation. I think summing it up in a blog post series is a good idea, so here you have the first one! A post covering how to secure XPC services is planned in the nearest future.
After reading Adam Chester’s neat article about bypassing macOS privacy controls, I decided to share my recently discovered trick. To bypass the Transparency, Consent, and Control service (TCC), we need an Electron application that already has some privacy permissions. As it turns out, you probably have at least one such app installed - look, for example, on your desktop messengers. Especially for this post, I created a simple Electron app that has access to the camera.