Security | DMA | Hacking

macOS FileVault2 let attackers with physical access retrieve the password in clear text by plugging in a $300 Thunderbolt device into a locked or sleeping mac. The password may be used to unlock the mac to access everything on it. To secure your mac just update it with the December 2016 patches. Anyone including, but not limited to, your colleagues, the police, the evil maid and the thief will have full access to your data as long as they can gain physical access - unless the mac is completely shut down. If the mac is sleeping it is still vulnerable. Just stroll up to a locked mac, plug in the Thunderbolt device, force a reboot (ctrl+cmd+power) and wait for the password to be displayed in less than 30 seconds! Check out the demo video below: How is this possible? At the very core of this issue there are two separate issues. The first issue is that the mac does not protect itself against Direct Memory Access (DMA) attacks before macOS is started. EFI which is running at this early stage...

It is possible to break Kernel Address Space Layout Randomization (KASLR) on modern operating systems running on modern x86 CPU's. One possible way of doing this is to time certain operations when using the Transactional Synchronization Extensions (TSX) instruction set. TSX makes it possible for unprivileged user mode programs to detect whether certain virtual memory pages are mapped or unmapped in kernel mode. It is also possible to detect whether a kernel page is executable or not. It has been known since at least 2014 that timing attacks against KASLR, using TSX, is possible. This was discussed by Rafal Wojtczuk from Bromium Labs in the blog post TSX improves timing attacks against KASLR . The technique was popularized and presented at Black Hat US-16 by Yeongjin, Sangho, and Taesoo from Georgia Institute of Technology. Their presentation and white paper is found on the Black Hat site. Example code for Linux was published on Github after the talk. Since no example code was pub...

I this post I will show how it's possible to disable Windows 10 Virtualization Based Security (VBS), Credential and Device Guard, by corrupting in-memory structures prior to operating system boot. For this attack to succeed the target computer must not be protected by a pre-boot authentication password. Auto-booting Bitlocker with TPM and/or Network unlock will work. The target computer is also required to have Direct Memory Access (DMA) capable ports and a BIOS which will allow DMA before operating system boot. The Target Intel NUC Skull Canyon with a Skylake i7 CPU. 32GB RAM. M.2 SSD. Windows 10 Enterprise version 1607. The NUC have two options for DMA. The obvious choice is the USB-C port at the back which is capable of Thunderbolt 3. Thunderbolt is however secure by default on the NUC - which is unfortunate for us. The Thunderbolt to PCI-Express adapters I use also doesn't seem to be working prior to OS boot even in the less secure Thunderbolt Legacy Mode. The second option...

I just got an Intel NUC Skull Canyon that has an USB-C port capable of Thunderbolt 3. Thunderbolt is interesting since it's able to carry PCI Express which is Direct Memory Access (DMA) capable. I have previously demonstrated how it is possible to DMA-attack macs over Thunderbolt 2 in my DEF CON talk "Direct Memory Attack the Kernel". To attack my MacBook Air in the DEF CON demo I used a Sonnet Echo ExpressCard Thunderbolt 2 to ExpressCard adapter together with a PCILeech ExpressCard. I also got a Thunderbolt 3 to Thunderbolt 2 adapter from Startech and I wanted to try it on the NUC to see if it's possible to use it for DMA attacks, or if Thunderbolt has been secured. The setup looks like this: NUC ->  Startech TB3 to TB2 adapter ->  Sonnet TB2 to ExpressCard adapter ->  PCILeech ExpressCard. There exists a BIOS setting for the Thunderbolt Security Level. The default setting is Unique ID . The other possible security levels are Legacy Mode , One time sa...