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                   - Advisory -
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  Tittle:   Checkpoint Endpoint Security Media Encryption EPM Explorer. Failed password limit bypass.
    Risk:   Low to Medium
    Date:   13.Nov.2013
  Author:   Pedro Andujar
   
              
.: [ INTRO ] :.

Checkpoint Endpoint Security Media Encryption EPM Explorer (Unlock.exe) comes with Endpoint Security 
suite and it's used as standalone tool to access the encrypted removable devices content from 
non-Media Encryption computers.


.: [ TECHNICAL DESCRIPTION ] :.

Checkpoint Endpoint Security Media Encryption Explorer v4.97.2 (Endpoint Security R73) contains two 
issues which can help to bypass the failed password attempts limit established in the password policy.

When accessing an encrypted removable device from a computer without Endpoint Security installed on it, 
it should contains the files described below:

DVREM.EPM - Encrypted Portable Media (aka the encrypted volume which contains data)
Unlock.exe - EPM Explorer (software which allows you to decrypt and access the content)

Despite other scenarios offers better performance (like attacking the EPM directly), less skilled attackers 
can take advantage of Unlock.exe to attempt to bruteforce the password.


.: [ ISSUE #1 }:.

Name: Multiple Unlock.exe instances 
Severity: Low
CVE: CVE-2013-5635
CWE-372: Incomplete Internal State Distinction

If password policy sets a limit of 5 failed password attempts before device is locked, executing n instances 
of Unlock.exe at the same time will allow you to get nx5 password attempts (5 for each instance).

Some controls should be applied to prevent multiple EPM explorers being concurrently executed, or at least 
synchronization regarding the state of failed password attempts.



.: [ ISSUE #2 }:.

Name: Device link not enforced
Severity: Low
CVE: CVE-2013-5636
CWE-285: Improper Authorization

Unlock.exe contains some restrictions that forces you to store the EPM file in the top of the directory tree,
just after a unit letter and coloms (Ex: X:\DVREM.EPM), so it cannot be inside a folder. But this is not enough
and still can be extracted from the removable media and be stored in a different drive.

Allowing Unlock.exe to be executed and access EPM stored on a different device/drive, increase the window
of time for attackers which can try to access the information without having the originally encrypted device on 
their hands.

Additionally everytime the EPM is overwrited by a freshcopy of itself, the failed password attempts is reseted,
allowing you to try another 5 times, so you can perform infinite attempts.

This charasteristic open some social engineering attack scenarios, like copying the EPM and Unlock.exe before 
returning a lent device to it's originall owner or just taking it for few seconds when owner is not paying atention. 

Ideally EPM file should be associated to the device ID at its creation time, and EPM explorer should check
the device ID (or other unique device identifier) to prevent it opening the EPM in a different location.



.: [ CHANGELOG ] :.

  * 16/Dec/2012:   - Issue found
  * 25/Aug/2013:   - Vendor contacted
  * 26/Aug/2013:   - Vendor Ack
  * 11/Nov/2013:   - Vendor finished the Fix for Issue #1
                   - Issue #2 considered not fixeable
  * 14/Nov/2013:   - Public Disclosure



.: [ SOLUTIONS ] :.

Check Point offers an improved client for this issue.

Solution ID: sk96589
https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk96589



.: [ REFERENCES ] :.

   [+] Check Point EndPoint Security R73 
    http://downloads.checkpoint.com/dc/download.htm?ID=10580

   [+] Checkpoint Security Alerts
    https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsecurityalerts

   [+] !dSR - Digital Security Research
    http://www.digitalsec.net/

   




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