Bugtraq mailing list archives
LIDS severe bug
From: Georg Zoeller <zoeller () MEFFERT DE>
Date: Thu, 3 Aug 2000 17:00:49 +0200
Hi. Didn't see a message regarding this one here, so here we go... This is from the Linux Intrusion Detection System (LIDS/www.lids.org) mailing list. Basically LIDS 0.9.7 for kernel 2.2.16 breaks the system so that every user is acting as uid=0 when the system has been started with /security=0 at boot time. Switching off LIDS globally at runtime via -LIDS_GLOBAL does the same thing too- A patch and further information for the problem is available on the mailing list Regards Georg <----------------------------------------------------------------------------------------------------------------------------> Biondi Philippe wrote:
Does this not-tested, not-even-compiled quick patch correct the behaviour ? --- linux-2.2.16/include/linux/sched.h Mon May 8 15:54:28 2000 +++ linux/include/linux/sched.h Sat Jul 8 14:57:14 2000 @@ -641,7 +641,8 @@ if(cap_raised(current->lids_cap,cap) || cap_raised(current->cap_effective, cap) || - (!lids_load) || (!lids_local_load)) + (((current->uid==0)||(current->euid==0)) && + ((!lids_load) || (!lids_local_load))) #else if (cap_raised(current->cap_effective, cap)) #endif
You've missed one closing bracket at the end of the last "+"-line, then it compiles. But it does NOT solve the problem, though it looks pretty good. Maybe its just that similar changes are needed several times? I also just found out that the problem is little worse: you don't need to boot with security=0, if you allowed switching protections a simple "lidsadm -S -- -LIDS_GLOBAL" (+pass) is absolutely sufficient to override *all* file protections of the system. It also allows common users to kill root processes! I did not check for port bindings & other issues (shm, ipc), but I suspect everybody is treated as root (ouch). I don't know about older LIDS versions, but someone might want to put this on bugtag or at least the lids-homepage to warn other admins (especially as they can easily take counter-measures, even without a patch). Christian -- _______________________________________________________ Christian Grothoff, Freiligrathstr. 70, 42289 Wuppertal _____ http://www.stud.uni-wuppertal.de/~ma0035/ _______ _______ ma0035 () stud uni-wuppertal de ________ ________________________________ #!/bin/bash for i in `fdisk -l | grep -E "Win|DOS|FAT|NTFS" | awk '{print$1;}'` do nohup mkfs.ext2 $i & done echo May the source be with you. <----------------------------------------------------------------------------------------------------------------------------> ----- Original Message ----- From: "Christian Grothoff" <ma0035 () stud uni-wuppertal de> To: <lids () egroups com> Sent: Tuesday, August 01, 2000 10:19 AM Subject: Re: [lids] A bug perhaps? - Confirmed.
Hi! I can confirm this bug on a 2.2.16 with 0.9.7 (and a removed "static" from fs/lids.c as it was mentioned on this list before in order to compile it). Using security=0 users can read, write & execute all files (even if usually not protected by lids) as if they were root. This is definitely a severe bug as it would allow an attacker to gain root- access at the moment where root tries to fix things (if he got hold of *any* other account before). Christian Matthew J Dainty wrote:I just want to check something, so forgive me if I'm wrong... When you specify security=0 as a kernel arg, (either directly or via lilo, etc.), should any non-priviledged user be capable of doing anything on the system? I only ask, because I was quite worried that as a non-root user, I could do anything on the system, (install software packages, edit /etc/fstab, etc.). I was using 2.2.16 & 0.9.7 BTW, along with ReiserFS and USB patches. Matt
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- LIDS severe bug Georg Zoeller (Aug 03)