BugTraq
BlackBerry Z 10 - Storage and Access File-Exchange Authentication By-Pass [MZ-13-04] Aug 12 2014 11:07AM
security (security modzero ch)
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modzero  Security Advisory:  BlackBerry  Z 10  -  Storage and  Access
File-Exchange Authentication By-Pass [MZ-13-04]

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1. Timeline

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 * 2013-06-23: Vendor has been contacted.
 * 2013-06-24: Vendor response.
 * 2013-06-27: Vendor meeting and information exchange.
 * 2013-08-20: Advisory and more details sent to the vendor.
 * 2013-10-15  or after patch-release: Advisory will be published.
 * 2013-12-05: Vendor requested delay of release, until a high level
               of carrier uptake has been achieved.
 * 2014-04-02: Vulnerabilities were fixed, but vendor requested delay
               of release, until a higher level of carrier uptake has
               been achieved.
 * 2014-08-11: Vendor achieved sufficient customer availability for
               this issue and announced release on August 12th, 2014.
 * 2014-08-12: Release of security advisory in cooperation with
               vendor.

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2. Summary

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Vendor: BlackBerry

Products known to be affected:
 * Blackberry Z10 model STL100-2
   Software release: 10.1.0.2312
   OS version: 10.1.0.2354
   Build ID: 524717

Severity: Medium
Remote exploitable: Yes
CVE: CVE-2014-2388

The mobile phone offers a  network service ("Storage and Access") for
adhoc file-exchange [1]  between the phone and a  network client [2].
To achieve these goals, the mobile device deploys a Samba fileserver,
which  can  be used  to  upload  or download  files  to  or from  the
Blackberry phone. To enable fileserver access from wireless networks,
the user has to explicitly enable  "Access using Wi-Fi" on the phone.
Afterwards,  the Z10  asks  the  user to  enter  a  password that  is
required   to  get   access   to  the   fileserver.  The   fileserver
implementation or  the password handling that  is used on the  Z10 is
affected by  an authentication by-pass vulnerability:  The fileserver
fails  to ask  for a  password  and allows  unauthenticated users  to
obtain read and  write access to the offered shares.  The severity is
considered medium to  high, as an attacker may be  able to distribute
targeted      malware      or     access      confidential      data.

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3. Details

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The problem occurs, when "Sharing via  Wi-Fi" has been enabled on the
Z10. The "Storage and  Access" dialog of the Z10 asks  the user for a
password that shall  be used to access data on  the fileserver. Under
certain circumstances, the fileserver fails to ask for a password and
allows  access even  without specifying  credentials. This  behaviour
does not always  occur but is reproducible within at  most one of ten
different tries via Wi-Fi.

The  following  lists describe  the  steps  of different  methods  to
reproduce  the  issue.  The  fist   approach  let  users  access  the
fileserver via the wireless LAN interface without using the developer
mode, which  is the most  common scenario. The second  approach gives
access via USB cable. In this  second approach, the developer mode is
activated to enable  TCP/IP communication via USB.  The second method
is more reliable for reproducing the effect and for tracking down the
root cause.

The root cause of the vulnerability is  not known at the time of this
writing. The  test was performed  with an  Ubuntu Linux as  a network
client. References to specific Linux tools are presented for the sake
of completeness.

3.1 Method 1

Prepare the phone:

1. Disconnect all cables
2. Open Settings / "Storage and Access" and make sure "Access using
   Wi-Fi" is turned off. This is not strictly necessary, but
   recommended to reproduce the effect.
3. Power down the phone.

The process to reproduce the problem:

1. Boot the phone.
2. Enter the PIN for the SIM card.
3. Enter the device password.
4. Open Settings
5. Open "Network Connections". Make sure that Wi-Fi is enabled and
   the phone is a client in a wireless LAN. In the test environment,
   the client IP address is 10.0.0.149.
6. For the tests, "Mobile Hotspot" is "Not Connected" and "Internet
   Tethering" is off. This setting is likely not critical.
7. Open "Storage and Access".
8. Enable "Access using Wi-Fi" on the phone. The phone will ask
   for a password. Use a password, which you never used before
   (for the server) to make sure, that credentials are not loaded
   from the Gnome keychain.
9. Open Nautilus with: nautilus smb://10.0.0.149
10. If Nautilus fails to display a lost of shares, close Nautilus and
    open it again.
11. Try to access a share. If the server asks for a password, disable
    "Access using Wi-Fi", reboot the phone and try again.

3.2 Method 2

Prepare the phone:

1. Connect phone to the PC via USB cable
2. Open Settings / "Storage and Access" and make sure "Access using
   Wi-Fi" is turned off.
3. Power down the phone.

The process to reproduce the problem:

1. Boot the phone.
2. Enter the PIN for the SIM card.
3. Enter the device password.
4. Open Settings
5. Open "Network Connections". Make sure that Wi-Fi is switched off,
   "Mobile Hotspot" is "Not Connected" and "Internet Tethering" is
   off.
6. Open "Development Mode" and enable it. The phone's IP address is
   set to 169.254.0.1.
7. Wait for the message: "Developer mode active ...".
8. Wait for the message: "Connected to PC ...".
9. Open "Storage and Access", make sure "Access using Wi-Fi" is
   disabled.
10. Open the Gnome file browser Nautilus from the command line with:
    nautilus smb://169.254.0.1
11. If Nautilus does not show any share, close Nautilus and open it
    again. If it is still empty, repeat the step.
12. Try to open a share: Nautilus will ask for a password. Click
    cancel. Nautilus will just ask again, press Cancel, again. This
    is expected behavior.
13. Close Nautilus
14. Open Nautilus, again, and leave the Nautilus window open.
15. Enable "Access using Wi-Fi" on the phone. The phone will ask for
   a password. Use a password, which you never used before (for the
   server) to make sure, that credentials are not stored in the Gnome
   keychain.
16. Click on a share, again. The share will be opened without asking
    for a password.
17. Disconnect share and open Nautilus again with:
    nautilus smb://169.254.0.1
18. Open a share. Nautilus will show the contents of the share.
19. Create a folder and create a file.

Shutdown process:

1. Disconnect shares
2. Disable "Access using Wi-Fi" in the phone's settings.
3. Shut down the phone.

A video of a demonstration is available at [3].

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4. Impact

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The  authentication  by-pass results  in  read  and write  access  to
enabled shares. Thus, sensitive data  may be accessed by unauthorized
or  malicious network  clients  or  users. Since  the  share is  also
writable,  attackers  are  able  to distribute  targeted  malware  to
certain mobile-phone users.

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5. Workaround

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To  reduce the  risks in  public wireless  networks, disable  "Access
using  Wi-Fi"  in  the  "Settings   /  Storage  and  Access"  dialog.

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6. Fix

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Vendor provided bugfix.

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7. Credits

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 * David Gullasch (dagu (at) modzero (dot) ch [email concealed])
 * Max Moser (mmo (at) modzero (dot) ch [email concealed])
 * Martin Schobert (martin (at) modzero (dot) ch [email concealed])

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8. About modzero

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The  independent  Swiss  company  modzero  AG  assists  clients  with
security analysis  in the complex  areas of computer  technology. The
focus  lies  on  highly  detailed  technical  analysis  of  concepts,
software  and  hardware components  as  well  as the  development  of
individual solutions.  Colleagues at  modzero AG work  exclusively in
practical, highly  technical computer-security areas and  can draw on
decades  of experience  in  various platforms,  system concepts,  and
designs.

http://modzero.ch

contact (at) modzero (dot) ch [email concealed]

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9. Disclaimer

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The information  in the advisory  is believed  to be accurate  at the
time of publishing  based on currently available  information. Use of
the information constitutes acceptance for use in an AS IS condition.
There are no warranties with  regard to this information. Neither the
author  nor  the publisher  accepts  any  liability for  any  direct,
indirect, or  consequential loss  or damage arising  from use  of, or
reliance on, this information.

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10. References

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[1] Moving or copying media files and documents:
   
http://docs.blackberry.com/en/smartphone_users/deliverables/47561/als133
4683894417.jsp
[2] How to copy files to and from a BlackBerry Z10 over a Wi-Fi
    network: http://helpblog.blackberry.com/2013/03/copy-z10-files-wifi/
[3] Proof-of-Concept video: http://modzero.ch/advisories/media/mz-13-04-poc.mp4

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See also:

http://www.modzero.ch/advisories/MZ-13-04-Blackberry_Z10-File-Exchange-A
uthentication-By-Pass.txt

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