Researchers have uncovered vulnerabilities in the widely deployed Ghostscript package that allows bad actors to remotely take control of vulnerable systems. There's no current patch available for the multiple flaws discovered.
Ghostscript is a suite of tools used by hundreds of software suites and coding libraries, which allows desktop software and web servers to handle Adobe Systems' PostScript and PDF page description languages.
Multiple bypass vulnerabilities, disclosed Tuesday, exist in the suite's optional -dSAFER feature, which is ironically supposed to prevent unsafe PostScript operations. By causing Ghostscript (or a program leveraging Ghostscript) to parse a specially-crafted malicious file, a remote, unauthenticated attacker may be able to execute arbitrary commands with the privileges of the Ghostscript code.
(Score: 0) by Anonymous Coward on Thursday August 23 2018, @03:10PM (4 children)
On Linux at least, is there any reason it would be running with elevated privileges?
(Score: 2, Informative) by Anonymous Coward on Thursday August 23 2018, @03:35PM
Typically gs would run at the privilege level of the user invoking the converter. So if you are logged in as root, well, that could then be a big problem.
But, gs is also invoked in a lot of other places. Like, i.e., as part of printing (i.e., cups).
And if cups is running as root, unless cups runs GS in a privilege reduced sandbox, then there's your vector to gaining root. Simply 'print' the malicious ps file as a normal user, and have it (the ps file) when it breaks out of gs make the necessary changes so you, normal user, gain a root shell.
(Score: 0) by Anonymous Coward on Friday August 24 2018, @02:48AM (2 children)
I changed /usr/bin/firefox to call the original binary 'su'ed to a neutered user whose shell is /sbin/nologin
That user has its own partition with web browser configuration files, etc. under it. All plugins activated by the browser are owned by that same user. /home and other important personal partitions can't be accessed by that user.
(Score: 0) by Anonymous Coward on Friday August 24 2018, @03:27AM (1 child)
How do you download files that you wish to keep? (Presumably a separate download manager but I am interested in your setup)
(Score: 2) by maxwell demon on Friday August 24 2018, @02:41PM
Well, the obvious way would be to download it to the browser's partition, and then copy the files to your normal user account with your normal user's tools.
The Tao of math: The numbers you can count are not the real numbers.