[Full-disclosure] Miscrosoft Registry Editor 5.1/XP/2K long string key vulnerability

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Date: Wed, 24 Aug 2005 11:01:11 +0400
To: bugs@securitytracker.com, news@securiteam.com, full-disclosure@lists.grok.org.uk, <vuln@secunia.com>

Hello All,

PRELUDE

/*
Registry Element Size Limits
The following are the size limits for the various registry elements.
The maximum size of a key name is 255 characters.
The maximum size of a value name is as follows:
Windows Server 2003 and Windows XP: 16,383 characters
Windows 2000: 260 ANSI characters or 16,383 Unicode characters.
Windows Me/98/95: 255 characters
Long values (more than 2,048 bytes) should be stored as files with the file names stored in the registry.
This helps the registry perform efficiently. The maximum size of a value is as follows:
Available memory.
Windows Me/98/95: 16,300 bytes. There is a 64K limit for the total size of all values of a key.
*/

DESCRIPTION

Microsoft Registry Editor for 2K and XP (Regedt32.exe) has a nice design flow
that is naturally allows to hide registry information from viewing and
editing even from users with administrative access. (really handful, thanks guys)

POC

To reproduce the desired behavior:

- run Regedt32.exe
- create a key, let it just be
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Empty
- in this key create any string value with the name exceeding 256
symbols (260 is the max) or just copy-paste:

helloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworl

Press F5 (refresh) and you will see how the key magically disappears.

Now create ANY key within
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Empty
and press refresh again - it will NOT BE SEEN by regedt32.

PRACTICE
There is a tremendous implementation field for this behavior.

TESTED
 On XP SP2 Eng, SP1 and 2K RUS. The testing is by no
 means complete but I hope it is working on all 2K and XP systems.
 Sorry if it is not.

SUGGESTED FIX
Make it possible to mange visibility by specifying (_?_) (_$_) and
(_._) in the key names.

-- 
www.rol.ru
Best regards,
 Igor                          mailto:sprog@online.ru
 
NOW SOME REALLY SERIOUS STUFF
Q:
  What does boot progress mean?
A:
  Bugs, they're warming up.
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• Previous message: Gaurav Kumar: "Re: [Full-disclosure] anybody remember the name of this tool"
• Next in thread: Jérôme ATHIAS: "Re: [Full-disclosure] Miscrosoft Registry Editor 5.1/XP/2K long string key vulnerability"
• Reply: Jérôme ATHIAS: "Re: [Full-disclosure] Miscrosoft Registry Editor 5.1/XP/2K long string key vulnerability"
• Reply: Spiro Trikaliotis: "Re: [Full-disclosure] Miscrosoft Registry Editor 5.1/XP/2K long string key vulnerability"
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