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Date: Fri, 11 Jan 2019 15:06:45 +0100
From: Solar Designer <solar@...nwall.com>
To: oss-security@...ts.openwall.com
Cc: Marcel Holtmann <marcel@...tmann.org>,
	Johan Hedberg <johan.hedberg@...il.com>
Subject: Linux kernel: Bluetooth: two remote infoleaks (CVE-2019-3459, CVE-2019-3460)

Hi,

Ran Menscher (Bcc'ed on this message) reported two issues (crediting
"Shlomi Oberman, Yuli Shapiro and Karamba Security Ltd. research team")
in Linux's Bluetooth stack to linux-distros and security@k.o on
January 1.  Unfortunately, but unsurprisingly to me, we collectively
failed to handle these issues well.  We did some things right, but not
all of those that ideally would have been done before embargo end.  From
the start, Ran was unwilling to precisely follow the linux-distros list
policy (set a tentative public disclosure date/time) and to stay on top
of the issues, instead expecting linux-distros to act more like a CERT
(coordinate with other parties), which it mostly is not.  I did point
this out to Ran, and suggested contacting Android, but I think no one
did that.  (See the third "forwarded message" below on this "not a CERT"
aspect and what can be done about it.)  The Bluetooth subsystem
maintainers didn't reply.  Distros appeared uninterested in doing
anything about the issues under embargo.  There were also numerous
occasions where I ended up substituting for other distros' roles they
had volunteered for.  And now I am doing Ran's job of making the
mandatory posting to oss-security (after a reminder yesterday).

On the bright side, I appreciate Greg KH's (security@k.o) handling of
these issues.  Greg took care of notifying the Bluetooth maintainers and
produced patches suitable for posting to the Linux lists (but still
needing review and testing), and made such postings as soon as the
embargo was over.  The thread with patches:

https://lore.kernel.org/linux-bluetooth/20190110062833.GA15047@kroah.com/

I also appreciate Yves-Alexis Perez (Debian) assigning the CVE IDs:

> On Tue, 2019-01-01 at 09:27 +0000, Ran Menscher wrote:
> > BUG 1 HEAP ADDRESS INFOLEAK IN USE OF L2CAP_GET_CONF_OPT
>  
> CVE-2019-3459
> 
> > BUG 2 HEAP DATA INFOLEAK IN MULTIPLE LOCATIONS INCLUDING FUNCTION
> > L2CAP_PARSE_CONF_RSP
>  
> CVE-2019-3460

Also very helpful was Ran's answer that "According to git blame, the
issues had been introduced in Linux-2.6.12-rc2 (in 2005)", and in the
first place the discovery of issues and the notification - thank you,
Ran and the Karamba Security research team!

Finally, I think it's good that we're pushing this out without further
delay (which no one requested).  Hopefully, we'll see greater progress
at handling of these issues now that the embargo is over.

I am sorry for the bitterness of my messages (including this one), which
I write from my list admin perspective.  I certainly understand that it
feels differently from a researcher perspective - for some, it'd be nice
to have a send-and-forget list, where the rest of the community would
take care of everything else.  It's just that such a list doesn't
currently exist.  There was oCERT for ~10 years, which provided this
service, but there was surprisingly little demand (vendor-sec and then
(linux-)distros saw much more use) and embargo times were much longer.

Alexander

----- Forwarded message from Ran Menscher <ran.menscher at karambasecurity.com> -----

From: Ran Menscher <ran.menscher at karambasecurity.com>
To: <linux-distros at vs.openwall.org>, <security at kernel.org>
Subject: [vs-plain] two information leak vulnerabilities in kernel bluetooth stack
CC: Guy Sagy <guy.sagy at karambasecurity.com>
Date: Tue, 1 Jan 2019 09:27:59 +0000


The Linux Kernel's Blutooth stack suffers from two remote information leak vulnerabilities in the code

that handles incoming L2cap configuration packets.
These were both discovered by Shlomi Oberman, Yuli Shapiro and  Karamba Security Ltd. research team.
We wish to coordinate a disclosure with all relevant parties.

BUG 1 ? HEAP ADDRESS INFOLEAK IN USE OF L2CAP_GET_CONF_OPT

VULNERABILITY
In the function l2cap_get_conf_opt (l2cap_core.c), which is used to parse configuration elements during
an L2cap connection negotiation process.
In this function, there is a ?dual use? for the output parameter ?val?. If the length of the data is 1,2 or 4, then
the returned value Is a value copied from an input buffer (received over BT) and returned ?by value?. If the
length is different, the value is returned as a pointer to the buffer ?by reference?. The buffer is from a kernel
SKB. Since the length is taken from the same buffer and the buffer is received via BT, the attacker controls
whether the val is returned as a pointer or as a value.
The val is later used as a value or as a pointer depending on a different field called ?type?, which is attacker
controlled and taken from the same buffer. The ?val? output parameter is assumed to match the ?type? and is
either used by reference or by value accordingly. This assumption is where the bug is. An attacker can send a
response where - for example ? the type is MTU (which uses 2 bytes from ?val? by-value), and the length is 3,
and so the returned MTU will actually be comprised of the 2 lower bytes of the pointer to the buffer, which
will be leaked to the attacker. It is a form of type confusion without having a sophisticated type system.

EXPLOIT
This flaw can be reached via multiple paths so there may be many ways to exploit it. One such example is using
a response with a ?rejected? result like in the known exploit for CVE-2017-1000251 for Amazon Echo, with an mtu config option sized 0
bytes. The returned mtu will then, usually, be the lower bytes of the pointer to the buffer.

EXPLOIT EFFECT
Leak bytes of heap address to attacker. Currently we only know and tested that it is possible a leak of the 2
lower bytes or a few bits of other data. bug still exists in latest kernel.



BUG 2 ? HEAP DATA INFOLEAK IN MULTIPLE LOCATIONS INCLUDING FUNCTION L2CAP_PARSE_CONF_RSP
VULNERABILITY
In the functions l2cap_parse_conf_rsp, l2cap_parse_conf_req (l2cap_core.c), and other locations, there is a while loop
which is used to parse configuration elements during an L2cap connection negotiation process.
In this function, the processing of data is performed in the while loop before the check if all the data processed
is inside the buffer. In addition, if data outside of the buffer is processed, the function will not return an error.
Therefore, data that is out of bands can be processed, and in some cases returned to the attacker.
EXPLOIT
This flaw can be reached via multiple paths so there may be many ways to exploit it. One such example is using
a response with a ?pending? status as with with the known exploit for CVE-2017-1000251 for Samsung Gear S3 exploit,
and make sure the request is aligned to the SKB buffer size and contains a configuration option at the end of the buffer which is of type ?EFS? and
length 0x10 (followed by 2 0x00 bytes). This efs element is then returned to the attacker and contains 0xE
bytes of out-of-bounds heap data. It is important to keep the total returned data size smaller then the return
buff size.
EXPLOIT EFFECT
Leak several bytes of heap data to attacker. Currently we only know that it is possible process 1 configuration
option per request, the length of which is at most the size of the largest configuration element. We have
internally tested a leak using an efs configuration option, leaking approx. 12 bytes. bug still exists in latest kernel.

PATCH (BOTH BUGS):


diff --git a/l2cap_core.c b/l2cap_core.c
index 2146e0f..8c38b32 100644
--- a/l2cap_core.c
+++ b/l2cap_core.c
@@ -2981,6 +2981,8 @@ static inline int l2cap_get_conf_opt(void **ptr, int *type, int *olen,

  default:
  *val = (unsigned long) opt->val;
+ if(opt->type != L2CAP_CONF_EFS && opt->type != L2CAP_CONF_RFC)
+ return -EPROTO;
  break;
  }

@@ -3332,11 +3334,16 @@ static int l2cap_parse_conf_req(struct l2cap_chan *chan, void *data, size_t data
  u16 mtu = L2CAP_DEFAULT_MTU;
  u16 result = L2CAP_CONF_SUCCESS;
  u16 size;
+ int res;

  BT_DBG("chan %p", chan);

  while (len >= L2CAP_CONF_OPT_SIZE) {
- len -= l2cap_get_conf_opt(&req, &type, &olen, &val);
+ res = l2cap_get_conf_opt(&req, &type, &olen, &val);
+ if(res < 0)
+ return -EPROTO;
+
+ len -= res;

  hint  = type & L2CAP_CONF_HINT;
  type &= L2CAP_CONF_MASK;
@@ -3354,7 +3361,7 @@ static int l2cap_parse_conf_req(struct l2cap_chan *chan, void *data, size_t data
  break;

  case L2CAP_CONF_RFC:
- if (olen == sizeof(rfc))
+ if (olen == sizeof(rfc) && && endptr - ptr >= L2CAP_CONF_OPT_SIZE + sizeof(rfc))
  memcpy(&rfc, (void *) val, olen);
  break;

@@ -3364,7 +3371,7 @@ static int l2cap_parse_conf_req(struct l2cap_chan *chan, void *data, size_t data
  break;

  case L2CAP_CONF_EFS:
- if (olen == sizeof(efs)) {
+ if (olen == sizeof(efs) && endptr - ptr >= L2CAP_CONF_OPT_SIZE + sizeof(efs)) {
  remote_efs = 1;
  memcpy(&efs, (void *) val, olen);
  }
@@ -3543,11 +3550,16 @@ static int l2cap_parse_conf_rsp(struct l2cap_chan *chan, void *rsp, int len,
  unsigned long val;
  struct l2cap_conf_rfc rfc = { .mode = L2CAP_MODE_BASIC };
  struct l2cap_conf_efs efs;
+ int res;

  BT_DBG("chan %p, rsp %p, len %d, req %p", chan, rsp, len, data);

  while (len >= L2CAP_CONF_OPT_SIZE) {
- len -= l2cap_get_conf_opt(&rsp, &type, &olen, &val);
+ res = l2cap_get_conf_opt(&rsp, &type, &olen, &val);
+ if(res < 0)
+ return -EPROTO;
+
+ len -= res;

  switch (type) {
  case L2CAP_CONF_MTU:
@@ -3566,7 +3578,7 @@ static int l2cap_parse_conf_rsp(struct l2cap_chan *chan, void *rsp, int len,
  break;

  case L2CAP_CONF_RFC:
- if (olen == sizeof(rfc))
+ if (olen == sizeof(rfc) && endptr - ptr >= L2CAP_CONF_OPT_SIZE + sizeof(rfc))
  memcpy(&rfc, (void *)val, olen);

  if (test_bit(CONF_STATE2_DEVICE, &chan->conf_state) &&
@@ -3586,7 +3598,7 @@ static int l2cap_parse_conf_rsp(struct l2cap_chan *chan, void *rsp, int len,
  break;

  case L2CAP_CONF_EFS:
- if (olen == sizeof(efs)) {
+ if (olen == sizeof(efs) && endptr - ptr >= L2CAP_CONF_OPT_SIZE + sizeof(efs)) {
  memcpy(&efs, (void *)val, olen);

  if (chan->local_stype != L2CAP_SERV_NOTRAFIC &&
@@ -3709,6 +3721,7 @@ static void l2cap_conf_rfc_get(struct l2cap_chan *chan, void *rsp, int len)
 {
  int type, olen;
  unsigned long val;
+ int res;
  /* Use sane default values in case a misbehaving remote device
  * did not send an RFC or extended window size option.
  */
@@ -3727,7 +3740,11 @@ static void l2cap_conf_rfc_get(struct l2cap_chan *chan, void *rsp, int len)
  return;

  while (len >= L2CAP_CONF_OPT_SIZE) {
- len -= l2cap_get_conf_opt(&rsp, &type, &olen, &val);
+ res = l2cap_get_conf_opt(&rsp, &type, &olen, &val);
+ if(res < 0)
+ return -EPROTO;
+
+ len -= res;

  switch (type) {
  case L2CAP_CONF_RFC:

----- End forwarded message -----

----- Forwarded message from Ran Menscher <ran.menscher at karambasecurity.com> -----

From: Ran Menscher <ran.menscher at karambasecurity.com>
To: Solar Designer <solar at openwall.com>
CC: <linux-distros at vs.openwall.org>, <security at kernel.org>, Guy Sagy <guy.sagy at karambasecurity.com>
Subject: Re: [vs-plain] two information leak vulnerabilities in kernel bluetooth stack
Date: Thu, 3 Jan 2019 10:24:32 +0000

Thank you Alexander.




The main priority is to coordinate a responsible fix prior to any disclosure.


This conflicts with the ultimatum system suggested which is more relevant to non-responsive vendors.


For this reason the previous mail had no such demands, and will for now accept any internal deadline you will decide on.




The same concern is with the bluetooth list, I hoped to reach the relevant parties via this secure list.


please aid in reaching any party relevant to fixing the issue, as long as responsible disclosure is maintained.




regarding the specific questions:


  1.  According to git blame, the issues had been introduced in Linux-2.6.12-rc2 (in 2005)
  2.  This issue is different than the reference brought in that it's remotely triggered.
  3.  We would appreciate your help with assigning a CVE ID.
  4.  proper diffs: as per my understanding, the difference should be merely the reference directory for git,


       I would unfortunately request that you make use of the given patch, as it will take me far too long to make further adjustments.




as I see the next steps:


  1.  I await your fix until a deadline of your suggestion
  2.  I only intervene again if no deadline has been decided on until January 14.
  3.  I would request that a proper notification will be sent when I'm both allowed and required to inform oss-security




Thanks,




________________________________
From: Solar Designer <solar at openwall.com>
Sent: 02 January 2019 13:54:52
To: Ran Menscher
Cc: linux-distros at vs.openwall.org; security at kernel.org; Guy Sagy
Subject: Re: [vs-plain] two information leak vulnerabilities in kernel bluetooth stack


Hi,


Replying for linux-distros:


On Tue, Jan 01, 2019 at 09:27:59AM +0000, Ran Menscher wrote:
> The Linux Kernel's Blutooth stack suffers from two remote information leak vulnerabilities in the code
> that handles incoming L2cap configuration packets.
> These were both discovered by Shlomi Oberman, Yuli Shapiro and  Karamba Security Ltd. research team.
> We wish to coordinate a disclosure with all relevant parties.


Per published linux-distros list policy, you were/are supposed to
specify a tentative public disclosure date/time (within 14 days max, so
January 14 at the latest and preferably sooner) in your very first
message.  Please do that ASAP.


Are these issues relevant to distros - in other words, when were they
introduced, what's the earliest affected version of the kernel?


Here's an example of Bluetooth issues reported a couple of months ago
and apparently being of no interest to distros:


https://www.openwall.com/lists/oss-security/2018/10/31/6


Your report looks better (it even includes patches), yet this lack of
interest in distros doing anything on kernel Bluetooth issues might
apply here as well.


Have you already requested CVE IDs for these?  If not, would you like
linux-distros to assign CVE IDs?


And then there's Greg's request for proper diffs and question about
notifying the Bluetooth maintainers.  We'd like to have that answer,
too.  Please note that the linux-bluetooth mailing list is public, so
only send to there if/once you intend to make the issues public.


BLUETOOTH SUBSYSTEM
M:      Marcel Holtmann <marcel@...tmann.org>
M:      Johan Hedberg <johan.hedberg@...il.com>
L:      linux-bluetooth@...r.kernel.org
W:      http://www.bluez.org/
T:      git git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git
T:      git git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git
S:      Maintained
F:      net/bluetooth/
F:      include/net/bluetooth/


Last but not least, please note that as soon as the issues are made
public, per linux-distros list policy you must post about them to the
public oss-security list.  Perhaps do this at the same time with making
your postings to linux-bluetooth, linux-kernel, and netdev lists, but
separately from the posting to those lists (don't use CC, but refer to
the other posting - please see my example linked above).


Thanks,


Alexander

----- End forwarded message -----

----- Forwarded message from Solar Designer <solar at openwall.com> -----

Date: Thu, 3 Jan 2019 23:53:43 +0100
From: Solar Designer <solar at openwall.com>
To: Ran Menscher <ran.menscher at karambasecurity.com>
Cc: linux-distros at vs.openwall.org, security at kernel.org, Guy Sagy <guy.sagy at karambasecurity.com>
Subject: Re: [vs-plain] two information leak vulnerabilities in kernel bluetooth stack

On Thu, Jan 03, 2019 at 10:24:32AM +0000, Ran Menscher wrote:
> The main priority is to coordinate a responsible fix prior to any disclosure.
> 
> This conflicts with the ultimatum system suggested which is more relevant to non-responsive vendors.

In my experience, this system is relevant regardless of which side the
delay would have been on.

> For this reason the previous mail had no such demands, and will for now accept any internal deadline you will decide on.

OK, if you don't, then I set these dates/times:

January 9, 15:00 UTC - tentative public disclosure date/time (may be
postponed if a good reason is given, but will be in effect otherwise).

January 14, 15:00 UTC - the latest allowed public disclosure date/time.

> The same concern is with the bluetooth list, I hoped to reach the relevant parties via this secure list.

You did reach some Linux distros and upstream Linux kernel security
team.  To also reach Bluetooth developers, please e-mail:

BLUETOOTH SUBSYSTEM
M:      Marcel Holtmann <marcel@...tmann.org>
M:      Johan Hedberg <johan.hedberg@...il.com>

or reply to Greg's offer to contact them for you (which I think is what
he meant).

> please aid in reaching any party relevant to fixing the issue, as long as responsible disclosure is maintained.

My guess is you'll want to notify the two persons above, and possibly
also notify Android security team.  (Android was on linux-distros
before, but quit for lack of actionable information for them in almost
all reports.  This one report might be an exception.)

We're not a CERT, so can't promise to act as such - coordinating with
other parties.  We do have this task/role listed:

https://oss-security.openwall.org/wiki/mailing-lists/distros#contributing-back

"4. Evaluate relevance to other parties such as the upstream, other
affected distros (not present on the (sub-)list), and other Open Source
projects, see if the report mentions notifying any of these, communicate
your findings and possible concerns to the reporter and the list, and
stay on top of the resulting discussion until a decision is made on who
else to possibly notify (or not) and any such notifications are in fact
made (with the reporter's approval)"

but so far no distro volunteered for this role (maybe distros present in
here should use your request as a reminder, and consider volunteering).

> regarding the specific questions:
> 
>   1.  According to git blame, the issues had been introduced in Linux-2.6.12-rc2 (in 2005)
>   2.  This issue is different than the reference brought in that it's remotely triggered.

OK, this is important.

>   3.  We would appreciate your help with assigning a CVE ID.

OK, I leave this to Red Hat or Debian to handle.

>   4.  proper diffs: as per my understanding, the difference should be merely the reference directory for git,
> 
>        I would unfortunately request that you make use of the given patch, as it will take me far too long to make further adjustments.

I don't see why.  But I'm not the one to make any use of your patches
anyway, so I'll leave this to others.

> as I see the next steps:
> 
>   1.  I await your fix until a deadline of your suggestion
>   2.  I only intervene again if no deadline has been decided on until January 14.
>   3.  I would request that a proper notification will be sent when I'm both allowed and required to inform oss-security

This is slightly different from our standard procedure, but OK.

Alexander

----- End forwarded message -----

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