Major Bug Grants Root For All Major Linux Distributions

One of the major reasons behind choosing Linux as an operating system is that it’s much more secure than Windows. There are plenty of reasons for this including appropriate user permissions, installing software from trusted sources and, of course, the fact that most software for Linux including the Linux kernel itself is open source which allows anyone to review the code for vulnerabilities. This doesn’t mean that Linux is perfectly secure though, as researchers recently found a major bug found in most major Linux distributions that allows anyone to run code as the root user.

The exploit is a memory corruption vulnerability in Polkit, a framework that handles the privilege level of various system processes. It specifically impacts the program pkexec. With the proof-of-concept exploit (file download warning) in hand, all an attacker needs to do to escalate themselves to root is to compile the program on the computer and run it as the default user. An example is shown by [Jim MacDonald] on Twitter for those not willing to try this on their own machines.

As bad as this sounds, it seems as though all of the major distributions that this impacts have already released updates that patch the issue, including Debian, Ubuntu, Red Hat, Fedora, open SUSE, and Arch. There is also a temporary workaround that removes read/write permission from the pkexec program so it can’t run at all. That being said, it might be best to check that your Linux systems are all up-to-date and that no strangers have been typing random commands into the terminal recently.

Software Removes The Facebook From Facebook’s VR Headset (Mostly)

It’s not a jailbreak, but [basti564]’s Oculess software nevertheless allows one the option to remove telemetry and account dependencies from Facebook’s Oculus Quest VR headsets. It is not normally possible to use these devices without a valid Facebook account (or a legacy Oculus account in the case of the original Quest), so the ability to flip any kind of disconnect switch without bricking the hardware is a step forward, even if there are a few caveats to the process.

To be clear, the Quest devices still require normal activation and setup via a Facebook account. But once that initial activation is complete, Oculess allows one the option of disabling telemetry or completely disconnecting the headset from its Facebook account. Removing telemetry means that details about what apps are launched, how the device is used, and all other usage-related data is no longer sent to Facebook. Disconnecting will log the headset out of its account, but doing so means apps purchased from the store will no longer work and neither will factory-installed apps like Oculus TV or the Oculus web browser.

What will still work is the ability to sideload unsigned software, which are applications that are neither controlled nor distributed by Facebook. Sideloading isn’t on by default; it’s enabled by putting the headset into Developer Mode (a necessary step to installing Oculess in the first place, by the way.) There’s a fairly active scene around unsigned software for the Quest headsets, as evidenced by the existence of the alternate app store SideQuest.

Facebook’s control over their hardware and its walled-garden ecosystem continues to increase, but clearly there are people interested in putting the brakes on where they can. It’s possible the devices might see a full jailbreak someday, but even if so, what happens then?

Rooting The Atari VCS 800

The Atari VCS 800 is a modern product, a hybrid of a PC and a games console. Fundamentally, its a bunch of modern chips in a box running Linux that will let you browse the web or emulate some old games. Now, thanks to [ArcadeHustle], you can have persistent root access to the VCS 800 at your leisure.

The trick is simple, and begins by interrupting the systemd startup scripts on boot. One can then merge files into the /etc directory to achieve root access, either by the tty terminal or over TCP. It’s all wrapped up in the script available at the Github link above.

You can actually run a variety of OSs on the hardware, as it’s powered by an AMD Ryzen R1606G CPU and runs straightforward PC architecture. However, if you want to customize the existing OS to do your bidding, this hack is the way to go.

Hacking to get root access is key if you want to get anywhere with a system. We’ve seen it done on thin clients as well as car infotainment systems to give the owner full control over the hardware they own. If you’ve got your own root exploit you’d like to share, do drop us a line, won’t you?

 

Linux Fu: Superpowers For Mere Mortals

You can hardly mention the sudo command without recalling the hilarious XKCD strip about making sandwiches. It does seem like sudo is the magic power to make a Linux system do what you want. The only problem is that those superpowers are not something to be taken lightly.

CC-BY-NC-2.5 by [XKCD]
If you are surfing the web, for example, you really don’t want to be root, because if someone naughty takes over your computer they could do a lot more harm with your root password. But still, there are times when you want to run certain commands that are normally root-only and don’t want to bother with a password. Luckily, sudo can handle that use case very easily.

Why?

As a simple example, suppose you like to shut your computer down at the end of the day. You run the shutdown command from the terminal but it doesn’t work because you aren’t root. You then have to do it again with sudo and if you haven’t logged in lately, provide your password. Ugh.

Continue reading “Linux Fu: Superpowers For Mere Mortals”

Nissan Gives Up Root Shell Thanks To Hacked USB Drive

For the impatient Nissan owners who may be joining us from Google, a hacker by the name of [ea] has figured out how to get a root shell on the Bosch LCN2kai head unit of their 2015 Xterra, and it looks like the process should be the same for other vehicles in the Nissan family such as the Rogue, Sentra, Altima, and Frontier. If you want to play along at home, all you have to do is write the provided image to a USB flash drive and insert it.

Now for those of us who are a more interested in how this whole process works, [ea] was kind of enough to provide a very detailed account of how the exploit was discovered. Starting with getting a spare Linux-powered head unit out of a crashed Xterra to experiment with, the write-up takes the reader through each discovery and privilege escalation that ultimately leads to the development of a non-invasive hack that doesn’t require the user to pull their whole dashboard apart to run.

The early stages of the process will look familiar to anyone who’s messed with embedded Linux hacking. The first step was to locate the board’s serial port and connect it to the computer. From there, [ea] was able to change the kernel parameters in the bootloader to spawn an interactive shell. To make things a little easier, the boot scripts were then modified so the system would start up an SSH server accessible over a USB Ethernet adapter. With full access to the system, the search for exploits could begin.

A simple script on the flash drive enables the SSH server.

After some poking, [ea] discovered the script designed to mount USB storage devices had a potential flaw in it. The script was written in such a way that the filesystem label of the device would be used to create the mount point, but there were no checks in place to prevent a directory traversal attack. By crafting a label that read ../../usr/bin/ and placing a Bash script on the drive, it’s possible to run arbitrary commands on the head unit. The provided script permanently adds SSHd to the startup process, so when the system reboots, you’ll be able to log in and explore.

So what does [ea] want to do with this new-found exploit? It looks like the goal is to eventually come up with some custom programs that extend the functionality of the in-dash Linux system. As it seems like these “infotainment” systems are now an inescapable feature of modern automobiles, we’re certainly excited to see projects that aim to keep them under the consumer’s control.

Exploring The Dell N1108T-ON Ethernet Switch

In an era where everything seems to be getting “smarter” every year, it will probably come as no surprise to find that even relatively middling networking hardware is now packing advanced features and considerable computational power. A case in point is the Dell N1108T-ON Ethernet switch. Despite only costing around $100 USD on the second hand market, [Ben Cox] discovered this particular switch was capable of a lot more than what was advertised by poking around its onboard operating system.

It all started by plugging into the serial port on the front of the switch, which [Ben] happily notes is an integrated FTDI USB serial adapter to make life easy. Booting into recovery mode gave him local shell access, and some poking around determines it’s the sort of BusyBox-powered Linux system that you’d expect on an embedded device. The biggest discoveries were that it was running a relatively recent kernel (3.8.1), and that it apparently had Python installed.

The reverse shell Python script

From there, [Ben] found out that these switches have a feature where the administrator can install and run Python “applications” by packaging them up as tarballs and copying them from a USB flash drive. So he wrote up a simple Python program that used the socket library to open up a reverse shell to his desktop computer, and to his surprise, it worked perfectly on the first try. Now with root access, the fun really started.

The next step was getting an SSH installed and running on the switch, so that he didn’t have to do the reverse shell trick every time. He then started installing the packages necessary to turn the switch into a secure VPN tunnel with Wireguard. This took a little fiddling as [Ben] didn’t have the option of installing the normal Wireguard kernel module, but he eventually got the necessary tools modified and cross-compiled to ARM. He believes this is just the start of what’s capable on devices like this, and we’re interested in seeing where the community goes from here.

We’ve seen hackers add management capability to a “dumb” unmanaged switch in the past, but software modifications like this promise to make the creation of custom, secure, networks far easier even on a hacker’s budget. A lot has certainly changed since the last time we saw somebody really dive into a professional Ethernet switch.

Rigol MSO5000 Hacked, Features Unlocked

Rigol’s test gear has something of a history of being hacked. Years ago the DS1022C oscillocope was hacked to increase bandwidth, and more recently the DS1054Z was hacked to unlock licensed features. Now, it’s the MSO5000’s turn.

Over on the EEVBlog forums a group has been working on hacking another Rigol, the MSO5000, a 70 MHz oscilloscope which can be upgraded to 350 MHz via software licensing. Various other features including a two channel, 25 MHz arbitrary waveform generator are also built-in, but locked out unless a license key is purchased. The group have managed to enable all the locked options without license keys.

The hack is quite simple. The Linux system running on the scope has a default root password of, you guessed it, “root”. After logging in over SSH with these credentials, the user just needs to modify the startup file to add the “-fullopt” flag to the “appEntry” application. This starts the application in a fully unlocked state, which gives access to all the features.

The MSO5000 costs about $1000, and the bandwidth option alone adds over $3000 to the price. If you’re willing to risk your warranty, and you have the skills to edit a file with vi, this hack provides a serious upgrade for free.

If you have a DS1022C you’ll find our reporting on its hack here, and likewise DS1054Z owners will find theirs here.

Header image: EEVBlog.