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Xen.org security team

2012-Sep-05 11:12 UTC

Xen Security Advisory 17 (CVE-2012-3515) - Qemu VT100 emulation vulnerability

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

            Xen Security Advisory CVE-2012-3515 / XSA-17
                           version 2

               Qemu VT100 emulation vulnerability

UPDATES IN VERSION 2
===================
Public release.

ISSUE DESCRIPTION
================
The device model used by fully virtualised (HVM) domains, qemu, does
not properly handle escape VT100 sequences when emulating certain
devices with a virtual console backend.

IMPACT
=====
An attacker who has sufficient privilege to access a vulnerable device
within a guest can overwrite portions of the device model''s address
space. This can allow them to escalate their privileges to that of the
device model process.

VULNERABLE SYSTEMS
=================
All Xen systems running HVM guests are potentially vulnerable to this
depending on the specific guest configuration. The default
configuration is vulnerable.

Guests using either the traditional "qemu-xen" or upstream qemu device
models are vulnerable.

MITIGATION
=========
This issue can be avoided by only running PV guests or by configuring
HVM guests to not use the virtual console(''vc'') backend for
any device.

For serial devices specify in your guest configuration:
     serial = ''none''
in your guest configuration.

For parallel port devices the syntax is toolstack specific.
For xend specify in your guest configuration:
     parallel = ''none''
For xl specify in your guest configuration:
     xl: device_model_args = [''-parallel'',
''none'']

In both cases the default is to use the vulnerable ''vc'' mode.

You can confirm whether or not you are vulnerable by pressing
Ctrl-Alt-<N> (for digit N) while connected to either the VNC or SDL
console. If you are able to switch to a window displaying "serial" or
"parallel" then you are vulnerable.

The issue can also be mitigated by enabling the stub domain device
model. In this case the attacked can only potentially gain control of
the stub domain and not of the entire system.

To enable stub domains specify in your guest configuration:
    device_model = "stubdom-dm"

RESOLUTION
=========
Applying the appropriate attached patch(es) will resolve the issue.

PATCH INFORMATION
================
The attached patches resolve this issue

Traditional qemu tree
   Xen 4.0, 4.1 and unstable         xsa17-qemu-xen-traditional-all.patch

Upstream qemu tree (present in unstable only)
   Xen unstable                      xsa17-qemu-xen-unstable.patch

$ sha256sum xsa17-*.patch
60215322d3fbbc2054dfc160a20d9e0811af88487c4edc2f6ea81dcd5cedf039 
xsa17-qemu-xen-traditional-all.patch
7b4bb59e7757080e7806a8b8eeb6b78fa0ffdfbfb28a7a379f7edff285bffd88 
xsa17-qemu-xen-unstable.patch
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_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel

Xen.org security team

2012-Sep-05 11:12 UTC

head link

Xen Security Advisory 17 (CVE-2012-3515) - Qemu VT100 emulation vulnerability

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

            Xen Security Advisory CVE-2012-3515 / XSA-17
                           version 2

               Qemu VT100 emulation vulnerability

UPDATES IN VERSION 2
===================
Public release.

ISSUE DESCRIPTION
================
The device model used by fully virtualised (HVM) domains, qemu, does
not properly handle escape VT100 sequences when emulating certain
devices with a virtual console backend.

IMPACT
=====
An attacker who has sufficient privilege to access a vulnerable device
within a guest can overwrite portions of the device model''s address
space. This can allow them to escalate their privileges to that of the
device model process.

VULNERABLE SYSTEMS
=================
All Xen systems running HVM guests are potentially vulnerable to this
depending on the specific guest configuration. The default
configuration is vulnerable.

Guests using either the traditional "qemu-xen" or upstream qemu device
models are vulnerable.

MITIGATION
=========
This issue can be avoided by only running PV guests or by configuring
HVM guests to not use the virtual console(''vc'') backend for
any device.

For serial devices specify in your guest configuration:
     serial = ''none''
in your guest configuration.

For parallel port devices the syntax is toolstack specific.
For xend specify in your guest configuration:
     parallel = ''none''
For xl specify in your guest configuration:
     xl: device_model_args = [''-parallel'',
''none'']

In both cases the default is to use the vulnerable ''vc'' mode.

You can confirm whether or not you are vulnerable by pressing
Ctrl-Alt-<N> (for digit N) while connected to either the VNC or SDL
console. If you are able to switch to a window displaying "serial" or
"parallel" then you are vulnerable.

The issue can also be mitigated by enabling the stub domain device
model. In this case the attacked can only potentially gain control of
the stub domain and not of the entire system.

To enable stub domains specify in your guest configuration:
    device_model = "stubdom-dm"

RESOLUTION
=========
Applying the appropriate attached patch(es) will resolve the issue.

PATCH INFORMATION
================
The attached patches resolve this issue

Traditional qemu tree
   Xen 4.0, 4.1 and unstable         xsa17-qemu-xen-traditional-all.patch

Upstream qemu tree (present in unstable only)
   Xen unstable                      xsa17-qemu-xen-unstable.patch

$ sha256sum xsa17-*.patch
60215322d3fbbc2054dfc160a20d9e0811af88487c4edc2f6ea81dcd5cedf039 
xsa17-qemu-xen-traditional-all.patch
7b4bb59e7757080e7806a8b8eeb6b78fa0ffdfbfb28a7a379f7edff285bffd88 
xsa17-qemu-xen-unstable.patch
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_______________________________________________
Xen-users mailing list
Xen-users@lists.xen.org
http://lists.xen.org/xen-users

Nathan March

2012-Sep-07 19:33 UTC

head link

Re: [Xen-users] Xen Security Advisory 17 (CVE-2012-3515) - Qemu VT100 emulation vulnerability

Hi All,

I''m guessing this wasn''t intentional, but the patch for xsa17
does not
contain a complete path to the tools/ioemu-qemu-xen/ path:

--- a/console.c
+++ b/console.c

Compared to all the other patches which provide a full path to the 
patched file:

--- a/xen/include/asm-x86/debugreg.h Mon Aug 06 12:28:03 2012 +0100
+++ b/xen/include/asm-x86/debugreg.h Wed Aug 15 12:00:21 2012 +0100

Little annoying since it means you have to track down which console.c 
is being patched instead of just applying from the root xen build dir.

- Nathan


------ Original Message ------
From: "Xen.org security team" <security@xen.org>
To: 
xen-announce@lists.xen.org;xen-devel@lists.xen.org;xen-users@lists.xen.org;oss-security@lists.openwall.com
Cc: "Xen.org security team" <security@xen.org>
Sent: 9/5/2012 4:12:47 AM
Subject: [Xen-users] Xen Security Advisory 17 (CVE-2012-3515) - Qemu 
VT100 emulation vulnerability>-----BEGIN PGP SIGNED MESSAGE-----
>Hash: SHA1
>
>           Xen Security Advisory CVE-2012-3515 / XSA-17
>                          version 2
>
>              Qemu VT100 emulation vulnerability
>
>UPDATES IN VERSION 2
>===================>
>Public release.
>
>ISSUE DESCRIPTION
>================>
>The device model used by fully virtualised (HVM) domains, qemu, does
>not properly handle escape VT100 sequences when emulating certain
>devices with a virtual console backend.
>
>IMPACT
>=====>
>An attacker who has sufficient privilege to access a vulnerable device
>within a guest can overwrite portions of the device model''s address
>space. This can allow them to escalate their privileges to that of the
>device model process.
>
>VULNERABLE SYSTEMS
>=================>
>All Xen systems running HVM guests are potentially vulnerable to this
>depending on the specific guest configuration. The default
>configuration is vulnerable.
>
>Guests using either the traditional "qemu-xen" or upstream qemu
device
>models are vulnerable.
>
>MITIGATION
>=========>
>This issue can be avoided by only running PV guests or by configuring
>HVM guests to not use the virtual console(''vc'') backend
for any device.
>
>For serial devices specify in your guest configuration:
>    serial = ''none''
>in your guest configuration.
>
>For parallel port devices the syntax is toolstack specific.
>For xend specify in your guest configuration:
>    parallel = ''none''
>For xl specify in your guest configuration:
>    xl: device_model_args = [''-parallel'',
''none'']
>
>In both cases the default is to use the vulnerable ''vc''
mode.
>
>You can confirm whether or not you are vulnerable by pressing
>Ctrl-Alt-<N> (for digit N) while connected to either the VNC or SDL
>console. If you are able to switch to a window displaying "serial"
or
>"parallel" then you are vulnerable.
>
>The issue can also be mitigated by enabling the stub domain device
>model. In this case the attacked can only potentially gain control of
>the stub domain and not of the entire system.
>
>To enable stub domains specify in your guest configuration:
>   device_model = "stubdom-dm"
>
>RESOLUTION
>=========>
>Applying the appropriate attached patch(es) will resolve the issue.
>
>PATCH INFORMATION
>================>
>The attached patches resolve this issue
>
>Traditional qemu tree
>  Xen 4.0, 4.1 and unstable         xsa17-qemu-xen-traditional-all.patch
>
>Upstream qemu tree (present in unstable only)
>  Xen unstable                      xsa17-qemu-xen-unstable.patch
>
>$ sha256sum xsa17-*.patch
>60215322d3fbbc2054dfc160a20d9e0811af88487c4edc2f6ea81dcd5cedf039 
xsa17-qemu-xen-traditional-all.patch
>7b4bb59e7757080e7806a8b8eeb6b78fa0ffdfbfb28a7a379f7edff285bffd88 
xsa17-qemu-xen-unstable.patch
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>

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel

Nathan March

2012-Sep-07 19:33 UTC

head link

Re: Xen Security Advisory 17 (CVE-2012-3515) - Qemu VT100 emulation vulnerability

Hi All,

I''m guessing this wasn''t intentional, but the patch for xsa17
does not
contain a complete path to the tools/ioemu-qemu-xen/ path:

--- a/console.c
+++ b/console.c

Compared to all the other patches which provide a full path to the 
patched file:

--- a/xen/include/asm-x86/debugreg.h Mon Aug 06 12:28:03 2012 +0100
+++ b/xen/include/asm-x86/debugreg.h Wed Aug 15 12:00:21 2012 +0100

Little annoying since it means you have to track down which console.c 
is being patched instead of just applying from the root xen build dir.

- Nathan


------ Original Message ------
From: "Xen.org security team" <security@xen.org>
To: 
xen-announce@lists.xen.org;xen-devel@lists.xen.org;xen-users@lists.xen.org;oss-security@lists.openwall.com
Cc: "Xen.org security team" <security@xen.org>
Sent: 9/5/2012 4:12:47 AM
Subject: [Xen-users] Xen Security Advisory 17 (CVE-2012-3515) - Qemu 
VT100 emulation vulnerability>-----BEGIN PGP SIGNED MESSAGE-----
>Hash: SHA1
>
>           Xen Security Advisory CVE-2012-3515 / XSA-17
>                          version 2
>
>              Qemu VT100 emulation vulnerability
>
>UPDATES IN VERSION 2
>===================>
>Public release.
>
>ISSUE DESCRIPTION
>================>
>The device model used by fully virtualised (HVM) domains, qemu, does
>not properly handle escape VT100 sequences when emulating certain
>devices with a virtual console backend.
>
>IMPACT
>=====>
>An attacker who has sufficient privilege to access a vulnerable device
>within a guest can overwrite portions of the device model''s address
>space. This can allow them to escalate their privileges to that of the
>device model process.
>
>VULNERABLE SYSTEMS
>=================>
>All Xen systems running HVM guests are potentially vulnerable to this
>depending on the specific guest configuration. The default
>configuration is vulnerable.
>
>Guests using either the traditional "qemu-xen" or upstream qemu
device
>models are vulnerable.
>
>MITIGATION
>=========>
>This issue can be avoided by only running PV guests or by configuring
>HVM guests to not use the virtual console(''vc'') backend
for any device.
>
>For serial devices specify in your guest configuration:
>    serial = ''none''
>in your guest configuration.
>
>For parallel port devices the syntax is toolstack specific.
>For xend specify in your guest configuration:
>    parallel = ''none''
>For xl specify in your guest configuration:
>    xl: device_model_args = [''-parallel'',
''none'']
>
>In both cases the default is to use the vulnerable ''vc''
mode.
>
>You can confirm whether or not you are vulnerable by pressing
>Ctrl-Alt-<N> (for digit N) while connected to either the VNC or SDL
>console. If you are able to switch to a window displaying "serial"
or
>"parallel" then you are vulnerable.
>
>The issue can also be mitigated by enabling the stub domain device
>model. In this case the attacked can only potentially gain control of
>the stub domain and not of the entire system.
>
>To enable stub domains specify in your guest configuration:
>   device_model = "stubdom-dm"
>
>RESOLUTION
>=========>
>Applying the appropriate attached patch(es) will resolve the issue.
>
>PATCH INFORMATION
>================>
>The attached patches resolve this issue
>
>Traditional qemu tree
>  Xen 4.0, 4.1 and unstable         xsa17-qemu-xen-traditional-all.patch
>
>Upstream qemu tree (present in unstable only)
>  Xen unstable                      xsa17-qemu-xen-unstable.patch
>
>$ sha256sum xsa17-*.patch
>60215322d3fbbc2054dfc160a20d9e0811af88487c4edc2f6ea81dcd5cedf039 
xsa17-qemu-xen-traditional-all.patch
>7b4bb59e7757080e7806a8b8eeb6b78fa0ffdfbfb28a7a379f7edff285bffd88 
xsa17-qemu-xen-unstable.patch
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>

_______________________________________________
Xen-users mailing list
Xen-users@lists.xen.org
http://lists.xen.org/xen-users

Nathan March

2012-Sep-07 19:38 UTC

head link

Re: [Xen-devel] Xen Security Advisory 17 (CVE-2012-3515) - Qemu VT100 emulation vulnerability

Same issue also applies to the xsa-19 patch.

- Nathan

------ Original Message ------
From: "Nathan March" <nathan@gt.net>
To: "Xen.org security team" 
<security@xen.org>;xen-devel@lists.xen.org;xen-users@lists.xen.org;oss-security@lists.openwall.com
Cc: "Xen.org security team" <security@xen.org>
Sent: 9/7/2012 12:33:42 PM
Subject: Re: [Xen-devel] [Xen-users] Xen Security Advisory 17 
(CVE-2012-3515) - Qemu VT100 emulation vulnerability>Hi All,
>I''m guessing this wasn''t intentional, but the patch for
xsa17 does not
>contain a complete path to the tools/ioemu-qemu-xen/ path:
>--- a/console.c
>+++ b/console.c
>Compared to all the other patches which provide a full path to the 
>patched file:
>--- a/xen/include/asm-x86/debugreg.h Mon Aug 06 12:28:03 2012 +0100
>+++ b/xen/include/asm-x86/debugreg.h Wed Aug 15 12:00:21 2012 +0100
>Little annoying since it means you have to track down which console.c 
>is being patched instead of just applying from the root xen build dir.
>- Nathan
>
>------ Original Message ------
>From: "Xen.org security team" <security@xen.org>
>To:
xen-announce@lists.xen.org;xen-devel@lists.xen.org;xen-users@lists.xen.org;oss-security@lists.openwall.com
>Cc: "Xen.org security team" <security@xen.org>
>Sent: 9/5/2012 4:12:47 AM
>Subject: [Xen-users] Xen Security Advisory 17 (CVE-2012-3515) - Qemu 
>VT100 emulation vulnerability
>>-----BEGIN PGP SIGNED MESSAGE-----
>>Hash: SHA1
>>
>>           Xen Security Advisory CVE-2012-3515 / XSA-17
>>                          version 2
>>
>>              Qemu VT100 emulation vulnerability
>>
>>UPDATES IN VERSION 2
>>===================>>
>>Public release.
>>
>>ISSUE DESCRIPTION
>>================>>
>>The device model used by fully virtualised (HVM) domains, qemu, does
>>not properly handle escape VT100 sequences when emulating certain
>>devices with a virtual console backend.
>>
>>IMPACT
>>=====>>
>>An attacker who has sufficient privilege to access a vulnerable device
>>within a guest can overwrite portions of the device model''s
address
>>space. This can allow them to escalate their privileges to that of the
>>device model process.
>>
>>VULNERABLE SYSTEMS
>>=================>>
>>All Xen systems running HVM guests are potentially vulnerable to this
>>depending on the specific guest configuration. The default
>>configuration is vulnerable.
>>
>>Guests using either the traditional "qemu-xen" or upstream
qemu device
>>models are vulnerable.
>>
>>MITIGATION
>>=========>>
>>This issue can be avoided by only running PV guests or by configuring
>>HVM guests to not use the virtual console(''vc'')
backend for any device.
>>
>>For serial devices specify in your guest configuration:
>>    serial = ''none''
>>in your guest configuration.
>>
>>For parallel port devices the syntax is toolstack specific.
>>For xend specify in your guest configuration:
>>    parallel = ''none''
>>For xl specify in your guest configuration:
>>    xl: device_model_args = [''-parallel'',
''none'']
>>
>>In both cases the default is to use the vulnerable
''vc'' mode.
>>
>>You can confirm whether or not you are vulnerable by pressing
>>Ctrl-Alt-<N> (for digit N) while connected to either the VNC or
SDL
>>console. If you are able to switch to a window displaying
"serial" or
>>"parallel" then you are vulnerable.
>>
>>The issue can also be mitigated by enabling the stub domain device
>>model. In this case the attacked can only potentially gain control of
>>the stub domain and not of the entire system.
>>
>>To enable stub domains specify in your guest configuration:
>>   device_model = "stubdom-dm"
>>
>>RESOLUTION
>>=========>>
>>Applying the appropriate attached patch(es) will resolve the issue.
>>
>>PATCH INFORMATION
>>================>>
>>The attached patches resolve this issue
>>
>>Traditional qemu tree
>>  Xen 4.0, 4.1 and unstable         xsa17-qemu-xen-traditional-all.patch
>>
>>Upstream qemu tree (present in unstable only)
>>  Xen unstable                      xsa17-qemu-xen-unstable.patch
>>
>>$ sha256sum xsa17-*.patch
>>60215322d3fbbc2054dfc160a20d9e0811af88487c4edc2f6ea81dcd5cedf039 
xsa17-qemu-xen-traditional-all.patch
>>7b4bb59e7757080e7806a8b8eeb6b78fa0ffdfbfb28a7a379f7edff285bffd88 
xsa17-qemu-xen-unstable.patch
>>-----BEGIN PGP SIGNATURE-----
>>Version: GnuPG v1.4.10 (GNU/Linux)
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>>-----END PGP SIGNATURE-----
>>
>>

_______________________________________________
Xen-users mailing list
Xen-users@lists.xen.org
http://lists.xen.org/xen-users

Nathan March

2012-Sep-07 19:38 UTC

head link

Re: [Xen-users] Xen Security Advisory 17 (CVE-2012-3515) - Qemu VT100 emulation vulnerability

Same issue also applies to the xsa-19 patch.

- Nathan

------ Original Message ------
From: "Nathan March" <nathan@gt.net>
To: "Xen.org security team" 
<security@xen.org>;xen-devel@lists.xen.org;xen-users@lists.xen.org;oss-security@lists.openwall.com
Cc: "Xen.org security team" <security@xen.org>
Sent: 9/7/2012 12:33:42 PM
Subject: Re: [Xen-devel] [Xen-users] Xen Security Advisory 17 
(CVE-2012-3515) - Qemu VT100 emulation vulnerability>Hi All,
>I''m guessing this wasn''t intentional, but the patch for
xsa17 does not
>contain a complete path to the tools/ioemu-qemu-xen/ path:
>--- a/console.c
>+++ b/console.c
>Compared to all the other patches which provide a full path to the 
>patched file:
>--- a/xen/include/asm-x86/debugreg.h Mon Aug 06 12:28:03 2012 +0100
>+++ b/xen/include/asm-x86/debugreg.h Wed Aug 15 12:00:21 2012 +0100
>Little annoying since it means you have to track down which console.c 
>is being patched instead of just applying from the root xen build dir.
>- Nathan
>
>------ Original Message ------
>From: "Xen.org security team" <security@xen.org>
>To:
xen-announce@lists.xen.org;xen-devel@lists.xen.org;xen-users@lists.xen.org;oss-security@lists.openwall.com
>Cc: "Xen.org security team" <security@xen.org>
>Sent: 9/5/2012 4:12:47 AM
>Subject: [Xen-users] Xen Security Advisory 17 (CVE-2012-3515) - Qemu 
>VT100 emulation vulnerability
>>-----BEGIN PGP SIGNED MESSAGE-----
>>Hash: SHA1
>>
>>           Xen Security Advisory CVE-2012-3515 / XSA-17
>>                          version 2
>>
>>              Qemu VT100 emulation vulnerability
>>
>>UPDATES IN VERSION 2
>>===================>>
>>Public release.
>>
>>ISSUE DESCRIPTION
>>================>>
>>The device model used by fully virtualised (HVM) domains, qemu, does
>>not properly handle escape VT100 sequences when emulating certain
>>devices with a virtual console backend.
>>
>>IMPACT
>>=====>>
>>An attacker who has sufficient privilege to access a vulnerable device
>>within a guest can overwrite portions of the device model''s
address
>>space. This can allow them to escalate their privileges to that of the
>>device model process.
>>
>>VULNERABLE SYSTEMS
>>=================>>
>>All Xen systems running HVM guests are potentially vulnerable to this
>>depending on the specific guest configuration. The default
>>configuration is vulnerable.
>>
>>Guests using either the traditional "qemu-xen" or upstream
qemu device
>>models are vulnerable.
>>
>>MITIGATION
>>=========>>
>>This issue can be avoided by only running PV guests or by configuring
>>HVM guests to not use the virtual console(''vc'')
backend for any device.
>>
>>For serial devices specify in your guest configuration:
>>    serial = ''none''
>>in your guest configuration.
>>
>>For parallel port devices the syntax is toolstack specific.
>>For xend specify in your guest configuration:
>>    parallel = ''none''
>>For xl specify in your guest configuration:
>>    xl: device_model_args = [''-parallel'',
''none'']
>>
>>In both cases the default is to use the vulnerable
''vc'' mode.
>>
>>You can confirm whether or not you are vulnerable by pressing
>>Ctrl-Alt-<N> (for digit N) while connected to either the VNC or
SDL
>>console. If you are able to switch to a window displaying
"serial" or
>>"parallel" then you are vulnerable.
>>
>>The issue can also be mitigated by enabling the stub domain device
>>model. In this case the attacked can only potentially gain control of
>>the stub domain and not of the entire system.
>>
>>To enable stub domains specify in your guest configuration:
>>   device_model = "stubdom-dm"
>>
>>RESOLUTION
>>=========>>
>>Applying the appropriate attached patch(es) will resolve the issue.
>>
>>PATCH INFORMATION
>>================>>
>>The attached patches resolve this issue
>>
>>Traditional qemu tree
>>  Xen 4.0, 4.1 and unstable         xsa17-qemu-xen-traditional-all.patch
>>
>>Upstream qemu tree (present in unstable only)
>>  Xen unstable                      xsa17-qemu-xen-unstable.patch
>>
>>$ sha256sum xsa17-*.patch
>>60215322d3fbbc2054dfc160a20d9e0811af88487c4edc2f6ea81dcd5cedf039 
xsa17-qemu-xen-traditional-all.patch
>>7b4bb59e7757080e7806a8b8eeb6b78fa0ffdfbfb28a7a379f7edff285bffd88 
xsa17-qemu-xen-unstable.patch
>>-----BEGIN PGP SIGNATURE-----
>>Version: GnuPG v1.4.10 (GNU/Linux)
>>
>>iQEcBAEBAgAGBQJQRx1PAAoJEIP+FMlX6CvZUqUH/jeAAvQnoBp6YKzm78XSnnmk
>>GI2C/LhH0xqR3wFoEmWeMsiO4lrGrASX6T31NTvHa8sOtFqlNpTfRhwQybwYR3aa
>>cz9/4y2a54hD95P1nVmPF0PddmSP47QSpRdCj0projq1UGxIdwEhkNeSoM8h7dXO
>>MegqZClsvJMKd8XEcjBF5Qg7u9vLrXilCx5+It7XNE31Jxpkr/fozBb7FnNtDGJj
>>s4RN/UDU4Pu68XyZ7Dc5xEFdJW48tz4BIlxxXavILBRFSE1VEf7Gc8H9CsUtBPWB
>>C/LCUjpHkAOmqdgFhiLnZ2u+2s79U0dtPDJMNmqaGgWH+AqGkU9Nq8XXODTyY9k>>=gnuE
>>-----END PGP SIGNATURE-----
>>
>>

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel

Andrew Cooper

2012-Sep-07 19:39 UTC

head link

Re: [Xen-users] Xen Security Advisory 17 (CVE-2012-3515) - Qemu VT100 emulation vulnerability

On 07/09/12 20:33, Nathan March wrote:> Hi All,
>
> I''m guessing this wasn''t intentional, but the patch for
xsa17 does notcontain a complete path to the tools/ioemu-qemu-xen/ path:

This is because it applies to the qemu repository, not the xen repository.

It just so happens that the xen repository build system will pull it
into a subdir to build it, if you dont do so manually.

~Andrew
> 
> --- a/console.c
> +++ b/console.c
>
> Compared to all the other patches which provide a full path to the
patched file:>
> --- a/xen/include/asm-x86/debugreg.h Mon Aug 06 12:28:03 2012 +0100
> +++ b/xen/include/asm-x86/debugreg.h Wed Aug 15 12:00:21 2012 +0100
>
> Little annoying since it means you have to track down which console.cis being patched instead of just applying from the root xen build
dir.>
> - Nathan
>
>
> ------ Original Message ------
> From: "Xen.org security team" <security@xen.org>
> To:
xen-announce@lists.xen.org;xen-devel@lists.xen.org;xen-users@lists.xen.org;oss-security@lists.openwall.com> Cc: "Xen.org security team" <security@xen.org>
> Sent: 9/5/2012 4:12:47 AM
> Subject: [Xen-users] Xen Security Advisory 17 (CVE-2012-3515) - Qemu
VT100 emulation vulnerability>            Xen Security Advisory CVE-2012-3515 / XSA-17
>                           version 2
>
>               Qemu VT100 emulation vulnerability
>
> UPDATES IN VERSION 2
> ===================>
> Public release.
>
> ISSUE DESCRIPTION
> ================>
> The device model used by fully virtualised (HVM) domains, qemu, does
> not properly handle escape VT100 sequences when emulating certain
> devices with a virtual console backend.
>
> IMPACT
> =====>
> An attacker who has sufficient privilege to access a vulnerable device
> within a guest can overwrite portions of the device model''s
address
> space. This can allow them to escalate their privileges to that of the
> device model process.
>
> VULNERABLE SYSTEMS
> =================>
> All Xen systems running HVM guests are potentially vulnerable to this
> depending on the specific guest configuration. The default
> configuration is vulnerable.
>
> Guests using either the traditional "qemu-xen" or upstream qemu
device
> models are vulnerable.
>
> MITIGATION
> =========>
> This issue can be avoided by only running PV guests or by configuring
> HVM guests to not use the virtual console(''vc'') backend
for any device.
>
> For serial devices specify in your guest configuration:
>     serial = ''none''
> in your guest configuration.
>
> For parallel port devices the syntax is toolstack specific.
> For xend specify in your guest configuration:
>     parallel = ''none''
> For xl specify in your guest configuration:
>     xl: device_model_args = [''-parallel'',
''none'']
>
> In both cases the default is to use the vulnerable ''vc''
mode.
>
> You can confirm whether or not you are vulnerable by pressing
> Ctrl-Alt-<N> (for digit N) while connected to either the VNC or SDL
> console. If you are able to switch to a window displaying
"serial" or
> "parallel" then you are vulnerable.
>
> The issue can also be mitigated by enabling the stub domain device
> model. In this case the attacked can only potentially gain control of
> the stub domain and not of the entire system.
>
> To enable stub domains specify in your guest configuration:
>    device_model = "stubdom-dm"
>
> RESOLUTION
> =========>
> Applying the appropriate attached patch(es) will resolve the issue.
>
> PATCH INFORMATION
> ================>
> The attached patches resolve this issue
>
> Traditional qemu tree
>   Xen 4.0, 4.1 and unstable         xsa17-qemu-xen-traditional-all.patch
>
> Upstream qemu tree (present in unstable only)
>   Xen unstable                      xsa17-qemu-xen-unstable.patch
>
> $ sha256sum xsa17-*.patch
> 60215322d3fbbc2054dfc160a20d9e0811af88487c4edc2f6ea81dcd5cedf039 
> xsa17-qemu-xen-traditional-all.patch
> 7b4bb59e7757080e7806a8b8eeb6b78fa0ffdfbfb28a7a379f7edff285bffd88 
> xsa17-qemu-xen-unstable.patch
-- 
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com


--------------070604010102000502080808
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    <meta content="text/html; charset=UTF-8"
http-equiv="Content-Type">
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    On 07/09/12 20:33, Nathan March wrote:<br>
    <span style="white-space: pre;">&gt; Hi All,<br>
      &gt; <br>
      &gt; I''m guessing this wasn''t intentional, but the
patch for xsa17
      does not contain a complete path to the tools/ioemu-qemu-xen/
      path:<br>
    </span><br>
    This is because it applies to the qemu repository, not the xen
    repository.<br>
    <br>
    It just so happens that the xen repository build system will pull it
    into a subdir to build it, if you dont do so manually.<br>
    <br>
    ~Andrew<br>
    <br>
    <span style="white-space: pre;">&gt; <br>
      &gt; --- a/console.c<br>
      &gt; +++ b/console.c<br>
      &gt; <br>
      &gt; Compared to all the other patches which provide a full path
      to the patched file:<br>
      &gt; <br>
      &gt; --- a/xen/include/asm-x86/debugreg.h Mon Aug 06 12:28:03 2012
      +0100<br>
      &gt; +++ b/xen/include/asm-x86/debugreg.h Wed Aug 15 12:00:21 2012
      +0100<br>
      &gt; <br>
      &gt; Little annoying since it means you have to track down which
      console.c is being patched instead of just applying from the root
      xen build dir.<br>
      &gt; <br>
      &gt; - Nathan<br>
      &gt; <br>
      &gt;<br>
      &gt; ------ Original Message ------<br>
      &gt; From: "Xen.org security team" <a
class="moz-txt-link-rfc2396E"
href="mailto:security@xen.org">&lt;security@xen.org&gt;</a><br>
      &gt; To:
<a class="moz-txt-link-abbreviated"
href="mailto:xen-announce@lists.xen.org;xen-devel@lists.xen.org;xen-users@lists.xen.org;oss-security@lists.openwall.com">xen-announce@lists.xen.org;xen-devel@lists.xen.org;xen-users@lists.xen.org;oss-security@lists.openwall.com</a><br>
      &gt; Cc: "Xen.org security team" <a
class="moz-txt-link-rfc2396E"
href="mailto:security@xen.org">&lt;security@xen.org&gt;</a><br>
      &gt; Sent: 9/5/2012 4:12:47 AM<br>
      &gt; Subject: [Xen-users] Xen Security Advisory 17 (CVE-2012-3515)
      - Qemu VT100 emulation vulnerability</span><br>
    <blockquote type="cite">           Xen Security Advisory
      CVE-2012-3515 / XSA-17<br>
                                version 2<br>
      <br>
                    Qemu VT100 emulation vulnerability<br>
      <br>
      UPDATES IN VERSION 2<br>
      ====================<br>
      <br>
      Public release.<br>
      <br>
      ISSUE DESCRIPTION<br>
      =================<br>
      <br>
      The device model used by fully virtualised (HVM) domains, qemu,
      does<br>
      not properly handle escape VT100 sequences when emulating
certain<br>
      devices with a virtual console backend.<br>
      <br>
      IMPACT<br>
      ======<br>
      <br>
      An attacker who has sufficient privilege to access a vulnerable
      device<br>
      within a guest can overwrite portions of the device model''s
      address<br>
      space. This can allow them to escalate their privileges to that of
      the<br>
      device model process.<br>
      <br>
      VULNERABLE SYSTEMS<br>
      ==================<br>
      <br>
      All Xen systems running HVM guests are potentially vulnerable to
      this<br>
      depending on the specific guest configuration. The default<br>
      configuration is vulnerable.<br>
      <br>
      Guests using either the traditional "qemu-xen" or upstream qemu
      device<br>
      models are vulnerable.<br>
      <br>
      MITIGATION<br>
      ==========<br>
      <br>
      This issue can be avoided by only running PV guests or by
      configuring<br>
      HVM guests to not use the virtual console(''vc'') backend
for any
      device.<br>
      <br>
      For serial devices specify in your guest configuration:<br>
          serial = ''none''<br>
      in your guest configuration.<br>
      <br>
      For parallel port devices the syntax is toolstack specific.<br>
      For xend specify in your guest configuration:<br>
          parallel = ''none''<br>
      For xl specify in your guest configuration:<br>
          xl: device_model_args = [''-parallel'',
''none'']<br>
      <br>
      In both cases the default is to use the vulnerable ''vc''
mode.<br>
      <br>
      You can confirm whether or not you are vulnerable by pressing<br>
      Ctrl-Alt-&lt;N&gt; (for digit N) while connected to either the VNC
      or SDL<br>
      console. If you are able to switch to a window displaying
"serial"
      or<br>
      "parallel" then you are vulnerable.<br>
      <br>
      The issue can also be mitigated by enabling the stub domain
device<br>
      model. In this case the attacked can only potentially gain control
      of<br>
      the stub domain and not of the entire system.<br>
      <br>
      To enable stub domains specify in your guest configuration:<br>
         device_model = "stubdom-dm"<br>
      <br>
      RESOLUTION<br>
      ==========<br>
      <br>
      Applying the appropriate attached patch(es) will resolve the
      issue.<br>
      <br>
      PATCH INFORMATION<br>
      =================<br>
      <br>
      The attached patches resolve this issue<br>
      <br>
      Traditional qemu tree<br>
        Xen 4.0, 4.1 and unstable        
      xsa17-qemu-xen-traditional-all.patch<br>
      <br>
      Upstream qemu tree (present in unstable only)<br>
        Xen unstable                     
xsa17-qemu-xen-unstable.patch<br>
      <br>
      $ sha256sum xsa17-*.patch<br>
      60215322d3fbbc2054dfc160a20d9e0811af88487c4edc2f6ea81dcd5cedf039 
      xsa17-qemu-xen-traditional-all.patch<br>
      7b4bb59e7757080e7806a8b8eeb6b78fa0ffdfbfb28a7a379f7edff285bffd88 
      xsa17-qemu-xen-unstable.patch<br>
    </blockquote>
    <br>
    -- <br>
    Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer<br>
    T: +44 (0)1223 225 900, <a class="moz-txt-link-freetext"
href="http://www.citrix.com">http://www.citrix.com</a><br>
    <br>
  </body>
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_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
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--===============0732460400532653199==--

Ian Campbell

2012-Sep-08 05:39 UTC

head link

Re: [Xen-users] Xen Security Advisory 17 (CVE-2012-3515) - Qemu VT100 emulation vulnerability

On Fri, 2012-09-07 at 20:39 +0100, Andrew Cooper wrote:> On 07/09/12 20:33, Nathan March wrote:
> > Hi All,
> > 
> > I''m guessing this wasn''t intentional, but the patch
for xsa17 does
> not contain a complete path to the tools/ioemu-qemu-xen/ path:
> 
> This is because it applies to the qemu repository, not the xen
> repository.
> 
> It just so happens that the xen repository build system will pull it
> into a subdir to build it, if you dont do so manually.
It''s also the case the in the tarball releases where qemu is
"pre-cloned" to that location.

We can''t easily satisfy both the repo and tarball scenarios in one
patch
but this is something we could clarify in the advisory text in the
future.

Ian.
> 
> ~Andrew
> 
> > 
> > --- a/console.c
> > +++ b/console.c
> > 
> > Compared to all the other patches which provide a full path to the
> patched file:
> > 
> > --- a/xen/include/asm-x86/debugreg.h Mon Aug 06 12:28:03 2012 +0100
> > +++ b/xen/include/asm-x86/debugreg.h Wed Aug 15 12:00:21 2012 +0100
> > 
> > Little annoying since it means you have to track down which
> console.c is being patched instead of just applying from the root xen
> build dir.
> > 
> > - Nathan
> > 
> >
> > ------ Original Message ------
> > From: "Xen.org security team" <security@xen.org>
> > To:
>
xen-announce@lists.xen.org;xen-devel@lists.xen.org;xen-users@lists.xen.org;oss-security@lists.openwall.com
> > Cc: "Xen.org security team" <security@xen.org>
> > Sent: 9/5/2012 4:12:47 AM
> > Subject: [Xen-users] Xen Security Advisory 17 (CVE-2012-3515) - Qemu
> VT100 emulation vulnerability
> >            Xen Security Advisory CVE-2012-3515 / XSA-17
> >                           version 2
> > 
> >               Qemu VT100 emulation vulnerability
> > 
> > UPDATES IN VERSION 2
> > ===================> > 
> > Public release.
> > 
> > ISSUE DESCRIPTION
> > ================> > 
> > The device model used by fully virtualised (HVM) domains, qemu, does
> > not properly handle escape VT100 sequences when emulating certain
> > devices with a virtual console backend.
> > 
> > IMPACT
> > =====> > 
> > An attacker who has sufficient privilege to access a vulnerable
> > device
> > within a guest can overwrite portions of the device model''s
address
> > space. This can allow them to escalate their privileges to that of
> > the
> > device model process.
> > 
> > VULNERABLE SYSTEMS
> > =================> > 
> > All Xen systems running HVM guests are potentially vulnerable to
> > this
> > depending on the specific guest configuration. The default
> > configuration is vulnerable.
> > 
> > Guests using either the traditional "qemu-xen" or upstream
qemu
> > device
> > models are vulnerable.
> > 
> > MITIGATION
> > =========> > 
> > This issue can be avoided by only running PV guests or by
> > configuring
> > HVM guests to not use the virtual console(''vc'')
backend for any
> > device.
> > 
> > For serial devices specify in your guest configuration:
> >     serial = ''none''
> > in your guest configuration.
> > 
> > For parallel port devices the syntax is toolstack specific.
> > For xend specify in your guest configuration:
> >     parallel = ''none''
> > For xl specify in your guest configuration:
> >     xl: device_model_args = [''-parallel'',
''none'']
> > 
> > In both cases the default is to use the vulnerable
''vc'' mode.
> > 
> > You can confirm whether or not you are vulnerable by pressing
> > Ctrl-Alt-<N> (for digit N) while connected to either the VNC or
SDL
> > console. If you are able to switch to a window displaying
"serial"
> > or
> > "parallel" then you are vulnerable.
> > 
> > The issue can also be mitigated by enabling the stub domain device
> > model. In this case the attacked can only potentially gain control
> > of
> > the stub domain and not of the entire system.
> > 
> > To enable stub domains specify in your guest configuration:
> >    device_model = "stubdom-dm"
> > 
> > RESOLUTION
> > =========> > 
> > Applying the appropriate attached patch(es) will resolve the issue.
> > 
> > PATCH INFORMATION
> > ================> > 
> > The attached patches resolve this issue
> > 
> > Traditional qemu tree
> >   Xen 4.0, 4.1 and unstable
> > xsa17-qemu-xen-traditional-all.patch
> > 
> > Upstream qemu tree (present in unstable only)
> >   Xen unstable                      xsa17-qemu-xen-unstable.patch
> > 
> > $ sha256sum xsa17-*.patch
> > 60215322d3fbbc2054dfc160a20d9e0811af88487c4edc2f6ea81dcd5cedf039
> > xsa17-qemu-xen-traditional-all.patch
> > 7b4bb59e7757080e7806a8b8eeb6b78fa0ffdfbfb28a7a379f7edff285bffd88
> > xsa17-qemu-xen-unstable.patch
> 
> -- 
> Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
> T: +44 (0)1223 225 900, http://www.citrix.com
>

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