lkrg-users - Re: bug: LKRG kills VirtualBox host VMs

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Date: Mon, 2 Dec 2019 19:00:44 +0100
From: Adam Zabrocki <pi3@....com.pl>
To: lkrg-users@...ts.openwall.com
Subject: Re: bug: LKRG kills VirtualBox host VMs

Hi,

I've looked into that deeper. As I was expecting, VirtualBox has a feature 
which allows to dynamically allocate RWX page and execute code from there. In 
the past this feature was vulnerable to be exploited by the user and used in 
the wild to bypass signature enforcement for executing kernel code:

https://www.virusbulletin.com/virusbulletin/2014/05/anatomy-turla-exploits/

This is a 'hacky' feature and it's violating some of the integrity rules which 
LKRG's ED feature enforces. However, I've introduced 2 compilation options 
which can relax some of the validation in LKRG and allows such a nasty 
functionality. They are DISABLED by default but if you really want you can 
enable it and compile LKRG with them. If you do so, you might run LKRG and 
VirtualBox together. To do that you should edit "src/p_lkrg_main.h" file and 
uncomment following definitions:

    #define P_LKRG_CI_X86_NO_MSR
    #define P_LKRG_PCFI_NO_STACKWALK

and recompile LKRG.

Thanks,
Adam

On Tue, Nov 19, 2019 at 07:06:04AM +0100, Adam Zabrocki wrote:
> Hi,
> 
> Thanks for report. From what I can see LKRG is somehow right since during stack 
> walk it detected code which was executed from the page which doesn't belong to 
> any legally registered .text section (kernel core neither kernel module):
> 
> Nov 18 08:30:59 debian kernel:  0xffffffffc106513b
> Nov 18 08:30:59 debian kernel:  0xffffffffc1065428
> Nov 18 08:30:59 debian kernel:  0xffffffffc108817d
> Nov 18 08:30:59 debian kernel:  0xffffffffc1088c24
> 
> However, it might be situation where VBox do some kind of JIT or any dynamic 
> code generation on dynamic page. I would be able to dig-in more when I set-up 
> repro environment for VirtualBox.
> I can tell that I'm using VmWare and haven't seen problem under LKRG so far.
> 
> Thanks,
> Adam
> 
> On Mon, Nov 18, 2019 at 06:58:00PM +0000, Patrick Schleizer wrote:
> > Debian buster host. LKRG 0.7.
> > 
> > This happened while VirtualBox 2 VMs were already running and installing
> > LRKG.
> > 
> > sudo dmesg | grep lkrg
> > [  336.576805] [p_lkrg] Loading LKRG...
> > [  337.126382] [p_lkrg] LKRG initialized successfully!
> > [  337.137161] [p_lkrg] <Exploit Detection> Not valid call - pCFI
> > violation: process[EMT-2 | 2067] !!!
> > [  337.137164] [p_lkrg] <Exploit Detection> Frame[1] nr_entries[8]:
> > [0xffffffffc106513b]. Full Stack:
> > [  337.137193] [p_lkrg] <Exploit Detection> Trying to kill process[EMT-2
> > | 2067]!
> > [  337.137234] [p_lkrg] <Exploit Detection> Stack pointer corruption
> > (ROP?) - pCFI violation: process[EMT-2 | 2067] !!!
> > [  337.137235] [p_lkrg] <Exploit Detection> Trying to kill process[EMT-2
> > | 2067]!
> > [  337.485911] [p_lkrg] <Exploit Detection> Not valid call - pCFI
> > violation: process[EMT-3 | 2116] !!!
> > [  337.485915] [p_lkrg] <Exploit Detection> Frame[1] nr_entries[8]:
> > [0xffffffffc106513b]. Full Stack:
> > [  337.485959] [p_lkrg] <Exploit Detection> Trying to kill process[EMT-3
> > | 2116]!
> > [  337.486014] [p_lkrg] <Exploit Detection> Stack pointer corruption
> > (ROP?) - pCFI violation: process[EMT-3 | 2116] !!!
> > [  337.486016] [p_lkrg] <Exploit Detection> Trying to kill process[EMT-3
> > | 2116]!
> > 
> > 
> > This happened after reboot when trying start a VM:
> > 
> > Nov 18 08:30:58 debian kernel: vboxdrv: 0000000000000000 VMMR0.r0
> > Nov 18 08:30:59 debian kernel: vboxdrv: 0000000000000000 VBoxDDR0.r0
> > Nov 18 08:30:59 debian kernel: vboxpci: created IOMMU domain
> > 000000000278fc42
> > Nov 18 08:30:59 debian kernel: [p_lkrg] <Exploit Detection> Not valid
> > call - pCFI violation: process[EMT-1 | 5252] !!!
> > Nov 18 08:30:59 debian kernel: [p_lkrg] <Exploit Detection> Frame[1]
> > nr_entries[8]: [0xffffffffc106513b]. Full Stack:
> > Nov 18 08:30:59 debian kernel: --- . ---
> > Nov 18 08:30:59 debian kernel:  schedule+0x1/0x80
> > Nov 18 08:30:59 debian kernel:  0xffffffffc106513b
> > Nov 18 08:30:59 debian kernel:  0xffffffffc1065428
> > Nov 18 08:30:59 debian kernel:  0xffffffffc108817d
> > Nov 18 08:30:59 debian kernel:  0xffffffffc1088c24
> > Nov 18 08:30:59 debian kernel:  supdrvIOCtl+0xca6/0x36a0 [vboxdrv]
> > Nov 18 08:30:59 debian kernel:  VBoxDrvLinuxIOCtl_6_0_14+0x15c/0x230
> > [vboxdrv]
> > Nov 18 08:30:59 debian kernel:  do_vfs_ioctl+0xa4/0x630
> > Nov 18 08:30:59 debian kernel: --- END ---
> > Nov 18 08:30:59 debian kernel: [p_lkrg] <Exploit Detection> Trying to
> > kill process[EMT-1 | 5252]!
> > Nov 18 08:30:59 debian kernel: [p_lkrg] <Exploit Detection> Stack
> > pointer corruption (ROP?) - pCFI violation: process[EMT-1 | 5252] !!!
> > Nov 18 08:30:59 debian kernel: [p_lkrg] <Exploit Detection> Trying to
> > kill process[EMT-1 | 5252]!
> > Nov 18 08:30:59 debian kernel: vboxpci: freeing IOMMU domain
> > 000000000278fc42
> > Nov 18 08:31:08 debian kernel: [p_lkrg] System is clean!
> > Nov 18 08:31:24 debian kernel: [p_lkrg] System is clean!
> > Nov 18 08:31:28 debian kernel: [p_lkrg] System is clean!
> > Nov 18 08:31:28 debian kernel: [p_lkrg] System is clean!
> > Nov 18 08:31:39 debian kernel: [p_lkrg] System is clean!
> > 
> > Kind regards,
> > Patrick
> 
> -- 
> pi3 (pi3ki31ny) - pi3 (at) itsec pl
> http://pi3.com.pl
> 

-- 
pi3 (pi3ki31ny) - pi3 (at) itsec pl
http://pi3.com.pl
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