BUGTRAQ has recently carried a report of a security
exploit against all current versions of LSOF up to and
including 4.40. Vic Abell, the author of LSOF, has
released a patch for it, in (email) message-id
on BUGTRAQ (with the subject 'Re: [HERT] Advisory #002
Buffer overflow in lsof'); the patch itself is at
(for lsof 4.40, clearly).
The original report of the problem was message-id
<19990218013035.B4950@red.blood.int> on BUGTRAQ and is
although it doesn't give any details.
(hopefully Bugzilla will preserve the angle brackets in
/dev/kmem under Linux is read-only, so it is not
vulnerable to a root compromise.
It's not clear to me if read access to kmem (apparently obtainable
through the lsof exploit on RedHat 5.2, since lsof is setgid kmem
and /dev/kmem is group-readable for kmem) can be used to do evil
things. RedHat might want to look into the situation and make a
statement one way or another. (Or it might be simpler and less time
consuming to just release new lsof RPMs built from 4.40 + Vic's
The immediate fix is
chmod g-s /usr/sbin/lsof
An updated errata of lsof-4.40 with Vic Abel's patch will be issued