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Eric Pretorious wrote: |
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> On Thursday 14 October 2004 08:15 pm, Dan Margolis wrote: |
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> |
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>>Following on your previous e-mail to the documentation editors, I would |
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>>appreciate it if you'd file a bug at |
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>>http://bugs.gentoo.org/enter_bug.cgi?product=Docs-user&format=guided. |
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> |
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> |
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> Done: http://bugs.gentoo.org/show_bug.cgi?id=67701 |
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> |
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> |
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>>As for this being widely known, it is not something I ever considered, |
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>>but it also is not, in and of itself, an exploit. |
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> |
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> |
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> True - It's not an exploit - But it's definitely a well-known weakness. |
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> |
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This isn't a weakness at all, presumably the attacker had root and could have |
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put these files anywhere, he just chose /dev/shm. |
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I can't imagine why he'd choose that as the rootkit would go away on reboot but |
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*shrug* |
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> |
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>>Presumably the attacker first used some other vulnerability to gain access to |
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>>your server. |
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> |
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> |
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> A valid user was able to install/execute a root-kit from /dev/shm. |
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> |
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> |
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>>Further, if I were to set up a server where I did not want to allow |
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>>users to execute anything but my own chosen binaries, I would probably |
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>>use GRSecurity's Trusted Path Execution, which allows a whitelist |
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>>approach (i.e. allow only root owned binaries in /bin or /usr/local/bin) |
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>>rather than trying to make sure our partitions are all mounted correctly. |
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> |
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> |
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trusted path is a broken concept. |
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> Had I known how easily Linux's security could be circumvented, I surely would |
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> have invested more time hardening the system. :( |
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> |
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:) linux's security system is hardly a security system at all. |
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> |
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>>That said, this is certainly a lapse in the Security Guide, and if you |
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>>file a bug I am sure it will be corrected shortly (if by nobody else, |
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>>than, soon as I have the time, I will write an update). |
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> |
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> |
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Don't think so. |
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I'm not sure if it's been mentioned but adding noexec wouldn't prevent this |
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since you can always run elf binaries through ld.so without directly executing |
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them and noexec doesn't prevent this. Further, as I already said, if he already |
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had root he could have put it anywhere he wanted, or even remounted /dev/shm |
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without noexec. There are no security gains here. |
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Joshua |
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-- |
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