=====[ Tempest Security Intelligence - ADV-6/2016 ]=============================
 
  Unsafe DLL search path in Telegram Desktop 0.10.1
  
  Author: Felipe Xavier Oliveira < engfilipeoliveira89 () gmail.com >
  
  Tempest Security Intelligence - Recife, Pernambuco - Brazil

=====[ Table of Contents ]======================================================
  
1. Overview  
2. Detailed description      
3. Timeline of disclosure    
4. Thanks & Acknowledgements  
5. References

=====[ 1. Overview ]============================================================
 
 * System affected  : Telegram Desktop.
 * Platform         : Windows.
 * Software Version : 0.10.1 (other versions may also be affected).
 * Impact           : If a low privileged user is infected, a malware is capable 
                      of injecting code into Telegram process (and steal 
                      Telegram messages) without the need of privilege 
                      escalation (i.e. ability to write to Program Files and/or 
                      system32).

=====[ 2. Detailed description ]================================================

Telegram Desktop version 0.10.1 is vulnerable to DLL Hijack, it tries to load 
"COMBASE.dll" without supplying the absolute path, thus relying upon the 
presence of such DLL on the system directory.

The issue is aggravated on Windows 7 because the DLL is not present, resulting 
in an exploitable DLL Hijack vulnerability, even though the SafeDllSerchMode 
flag is enabled. 

=====[ 3. Timeline of disclosure ]==============================================

08/11/2016 - Reported vulnerability [1].
08/14/2016 - Telegram fixed vulnerability [2].
12/11/2016 - Advisory publication date.
16/12/2016 - CVE assigned [3].

=====[ 4. Thanks & Acknowledgements ]===========================================
 
- Breno Cunha    < brenodario () gmail.com >
- Felipe Azevedo < felipe3gomes () gmail.com >
- Tempest Security Intelligence / Tempest's Pentest Team [4]
 
=====[ 5. References ]==========================================================

[1] https://github.com/telegramdesktop/tdesktop/issues/2350

[2] https://github.com/telegramdesktop/tdesktop/commit/50b10ba0bf61fc5d30f033e239b5a81ac478ec78

[3] https://github.com/distributedweaknessfiling/DWF-Database-Artifacts/blob/158c10cf11bc7d6ad728c1a8dd213f523ecfca52/DWF/2016/1000276/CVE-2016-1000276.json

[4] http://www.tempest.com.br

=====[ EOF ]====================================================================