Messages in this thread | | | Date | Wed, 28 Mar 2001 03:57:44 -0800 | From | Ben Ford <> | Subject | Re: Disturbing news.. |
| |
Simon Williams wrote:
> In message <20010328100440.A5941@zalem.puupuu.org>, Olivier Galibert > <galibert@pobox.com> writes > >> On Wed, Mar 28, 2001 at 03:04:46PM +0100, Simon Williams wrote: >> >>> I think their point was that a program could only change permissions >>> of a file that was owned by the same owner. If a file is owned by a >>> different user & has no write permissions for any user, the program >>> can't modify the file or it's permissions. >> >> You mean, you usually have write permissions for other than the owner >> on executable files? >> >> Let me reformulate that. You usually have write permissions for other >> than the owner, and not only on some special, untrusted log files (I'm >> talking files, here, not device nodes)? What's your umask, 0? >> > > Firstly, I'm relatively new to Linux (only about 3 yrs experience) & > don't claim to be an expert. Secondly, I don't think I stated my point > very clearly. > > No, I don't have write permissions set on an executable for any user > other than the owner. > > What I meant was that if a file is owned by root with permissions of, > say, 555 (r-xr-xr-x), not setuid or setgid, then another executable > run as a non-root user cannot modify it or change the permissions to > 7 (rwx).
There are two problems I see here. First, there are several known ways to elevate privileges. If a virus can elevate privileges, then it owns you. Second, this is a multi-OS virus. If you dual-boot into Windows, any ELF files accessible can be infected. With this one, that isn't a prob, but when somebody codes in an ext2 driver to their virus, then we've got issues.
-b
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |