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Cryptsetup Vulnerability Grants Root Shell Access On Some Linux Systems (threatpost.com)
msm1267 quotes a report from Threatpost: A vulnerability in cryptsetup, a utility used to set up encrypted filesystems on Linux distributions, could allow an attacker to retrieve a root rescue shell on some systems. From there, an attacker could have the ability to copy, modify, or destroy a hard disk, or use the network to exfiltrate data. Cryptsetup, a utility used to setup disk encryption based on the dm-crypt kernel module, is usually deployed in Debian and Ubuntu. Researchers warned late last week that if anyone uses the tool to encrypt system partitions for the operating systems, they're likely vulnerable. Two researchers, Hector Marco of the University of the West of Scotland and Ismael Ripoll, of the Polytechnic University of Valencia, in Spain, disclosed the vulnerability on Friday at DeepSec, a security conference held at the Imperial Riding School Renaissance Vienna Hotel in Austria. According to a post published to the Full Disclosure mailing list, the vulnerability (CVE-2016-4484) affects packages 2.1 and earlier. Systems that use Dracut, an infrastructure commonly deployed on Fedora in lieu of initramfs -- a simple RAM file system directory, are also vulnerable, according to the researchers. The pair say additional Linux distributions outside of Debian and Ubuntu may be vulnerable, they just haven't tested them yet. The report adds: "The problem stems from the incorrect handling of a password check when a partition is ciphered with LUKS, or Linux Unified Key Setup, a disk encryption specification that's standard for Linux. Assuming an attacker has access to the computer's console, when presented with the LUKS password prompt, they could exploit the vulnerability simply by pressing 'Enter' over and over again until a shell appears. The researchers say the exploit could take as few as 70 seconds. After a user exceeds the maximum number of three password tries, the boot sequence continues normally. Another script in the utility doesn't realize this, and drops a BusyBox shell. After carrying out the exploit, the attacker could obtain a root initramfs, or rescue shell. Since the shell can be executed in the initrd, or initial ram disk, environment, it can lead to a handful of scary outcomes, including elevation of privilege, information disclosure, or denial of service."
How is dropping to initrd "root" access?
1. If you already have physical access to the console, all bets are off anyway. Security 101.
2. If you have WDE enabled, dropping to root gets you initrd only - no passwords, no privileges, nada - all it lets you do is try to mount the file system which can't be because it's encrypted. Only /boot should be unencrypted.
3. The only possible attack vector is to swap out the kernel image. But there are simpler ways to do that than run an exploit.
Did these guys watch too many episodes of the new MacGyver and consider themselves hackers instead of script kiddies?
Did they report the problem as only present if you encrypt specific volumes (which is stupid anyway because your passwords are visible now).
It takes a lot of effort to avoid WDE when installing linux these days. Only an idiot would misconfigure and render his system vulnerable like this. And only an idiot would give his keys to the castle to people he didn't trust.
Social Engineering wins every time and there is nothing you can do about it.