oss-sec mailing list archives
Re: Breaking the links: Exploiting the linker
From: Jamie Nguyen <dyscoria () gmail com>
Date: Wed, 22 Dec 2010 11:46:41 +0000 (UTC)
Tim Brown <timb@...> writes:
In the interests of a thorough peer review I'd be curious what people think of the following paper I've been working on Linux and POSIX linkers: http://www.nth-dimension.org.uk/downloads.php?id=77 A previous revision has already been reviewed but constructive criticism is always useful. There are some sections that I have removed whilst I wait on vendors but I'm particularly interested in feedback on pertinent references or threats that I may have missed. As per the abstract, the aim of the paper wasn't to claim everything as my own but rather to document as much about the current state of art as possible. Tim
Hi, I am somewhat unknowledgeable about the whole linking process, but I was testing out the execution of a file using ld on a filesystem mounted with noexec. I followed the example you gave of copying the '/usr/bin/id' executable to a user writeable directory and removing the executable bit. After removing the executable bit, I was still able to execute this on a normal filesystem using /lib/ld-linux-x86_64.so.2 but on a filesystem mounted with noexec this method did not work. You suggest in the article: "...if you're mounting devices with noexec the you should probably ensure that they [sic] the runtime linker can't be executed either." Forgive me if I am being dim, because from what I can see, mounting with noexec seems to solve the issue of using ld-linux-x86-64.so.2 to execute non-executable files. I notice in your example that you are using eglibc. I am testing with glibc, so perhaps this is the reason? Kind regards Jamie
Current thread:
- Breaking the links: Exploiting the linker Tim Brown (Dec 14)
- Re: Breaking the links: Exploiting the linker Tomas Hoger (Dec 15)
- Re: Breaking the links: Exploiting the linker Justin Ossevoort (Dec 15)
- Re: Breaking the links: Exploiting the linker Tim Brown (Dec 16)
- Re: Breaking the links: Exploiting the linker Ralf Wildenhues (Dec 16)
- Re: Re: Breaking the links: Exploiting the linker Tim Brown (Dec 16)
- Re: Breaking the links: Exploiting the linker Jamie Nguyen (Dec 22)
- Re: Re: Breaking the links: Exploiting the linker Tim Brown (Dec 22)
- Re: Breaking the links: Exploiting the linker Jamie Nguyen (Dec 22)
- Re: Re: Breaking the links: Exploiting the linker Tim Brown (Dec 22)
- Re: Breaking the links: Exploiting the linker Tomas Hoger (Dec 15)