Binance v1.5.0 - Insecure File Permission Vulnerability

Document Title:
===============
Binance v1.5.0 - Insecure File Permission Vulnerability


References (Source):
====================
https://www.vulnerability-lab.com/get_content.php?id=2135


Release Date:
=============
2018-07-16


Vulnerability Laboratory ID (VL-ID):
====================================
2135


Common Vulnerability Scoring System:
====================================
2.5


Vulnerability Class:
====================
Access Permission Weakness


Current Estimated Price:
========================
500€ - 1.000€


Abstract Advisory Information:
==============================
An independent vulnerability laboratory researcher discovered an insecure file permission vulnerability in the Binance v1.5.0 software.



Vulnerability Disclosure Timeline:
==================================
2018-07-15: Researcher Notification & Coordination (Security Researcher)
2018-07-17: Public Disclosure (Vulnerability Laboratory)


Discovery Status:
=================
Published


Affected Product(s):
====================
Binance
Product: Binance 1.5.0


Exploitation Technique:
=======================
Local


Severity Level:
===============
Low


Authentication Type:
====================
Restricted Authentication (User Privileges)


User Interaction:
=================
Medium User Interaction


Disclosure Type:
================
Full Disclosure


Technical Details & Description:
================================
Insecure File Permissions vulnerability has been discovered in the official Binance v1.5.0 software.
The vulnerability allows local attackers to exploit insecure permissions setup for a software or process to exploit by manipulation.

The vulnerability exists due to insecure default permissions set on the Binance.exe, start.exe and unins000.exe  
There are no integrity checks or validation proof to ensure that the executable file is not modified 
during the runtime or after it.
A local attacker could exploit the local vulnerability by replacing `Binance.exe` and `start.exe` or `unins000.exe` with a 
malicious executable file.  The malicious file could execute or modify with the LocalSystem permissions to followup with 
successful exploitation.


Proof of Concept (PoC):
=======================
Binance for windows contains a vulnerability that could allow a local attacker to gain elevated privileges.
For security demonstration or to reproduce the vulnerability follow the provided information and steps below.


-- PoC Session Logs (Permissions) --
C:Binance>icacls binance.exe
Binance.exe BUILTINAdministrateurs:(I)(F)         <--- Full Access
 AUTORITE NTSystème:(I)(F)
 BUILTINUtilisateurs:(I)(RX)
 AUTORITE NTUtilisateurs authentifiés:(I)(M)       <--- Modify

Information: 1 files correctly processed; 0 files failed to process

C:Binance>icacls start.exe
start.exe BUILTINAdministrateurs:(I)(F)         <--- Full Access
 AUTORITE NTSystème:(I)(F)
 BUILTINUtilisateurs:(I)(RX)
 AUTORITE NTUtilisateurs authentifiés:(I)(M)     <--- Modify

Information: 1 files correctly processed; 0 files failed to process

C:Binance>icacls unins000.exe
unins000.exe BUILTINAdministrateurs:(I)(F)       <--- Full Access
 AUTORITE NTSystème:(I)(F)
 BUILTINUtilisateurs:(I)(RX)
 AUTORITE NTUtilisateurs authentifiés:(I)(M)    <--- Modify

Information: 1 files correctly processed; 0 files failed to process


Solution - Fix & Patch:
=======================
Include multiple integrity checks for the software files on startup and during the static runtime.
Change the access permissions for the process of all three executables files (binance.exe, stat.exe & uninst00.exe).


Security Risk:
==============
The security risk of the insecure file permissions vulnerability and missing integrity check in the software core is estimated as low. 


Credits & Authors:
==================
ZwX [Vulnerability Laboratory - Security Manager] - https://www.vulnerability-lab.com/show.php?user=ZwX


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=========================
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