[Esa-l] EEYE: Remote PGP Outlook Encryption Plug-in Vulnerability (fwd)

[John D. Hardin]

--
 John Hardin KA7OHZ    ICQ#15735746    http://www.impsec.org/~jhardin/
 jhardin at impsec.org                        pgpk -a jhardin at impsec.org
  768: 0x41EA94F5 - A3 0C 5B C2 EF 0D 2C E5  E9 BF C8 33 A7 A9 CE 76 
 1024: 0xB8732E79 - 2D8C 34F4 6411 F507 136C  AF76 D822 E6E6 B873 2E79
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   313 days until The Matrix Reloaded

---------- Forwarded message ----------
Date: Wed, 10 Jul 2002 16:04:11 -0700
From: Marc Maiffret <marc at eeye.com>
To: BUGTRAQ <BUGTRAQ at securityfocus.com>
Subject: EEYE: Remote PGP Outlook Encryption Plug-in Vulnerability

Remote PGP Outlook Encryption Plug-in Vulnerability

Release Date:
July 10, 2002

Severity:
High (Remote Code Execution)

Systems Affected:
NAI PGP Desktop Security 7.0.4
NAI PGP Personal Security 7.0.3
NAI PGP Freeware 7.0.3

Description:

The beer is still cold, the days are still long, the exploits still start as
jokes (this time over a beer with a three letter agency) and the
advisories... we'll just say, "All of your SCADA are belong to us."

A vulnerability in the NAI PGP Outlook plug-in can be exploited to remotely
execute code on any system that uses the NAI PGP Outlook plug-in's. By
sending a carefully crafted email the message decoding functionality can be
manipulated to overwrite various heap structures pertinent to the PGP
plug-in.

This vulnerability can be exploited by a user simply selecting a "malicious'
email, the opening of attachments is not required. When the attack is
performed against a target system, malicious code will be executed within
the context of the user receiving the email. This can lead to the compromise
of the targets machine, as well as their PGP encrypted communications. It
should also be noted that because of the nature of the SMTP protocol this
vulnerability can be exploited anonymously.

Technical Description:

Exploitation:

By creating a malformed email we can overwrite a section of heap memory that
contains various data. By overwriting this section of heap with valid
addresses of an unused section in the PEB, which is the same across all NT
systems, we can walk the email parsing and eventually get to something
easily exploitable:

CALL DWORD PTR [ecx]

This pointer addresses references a function pointer list. At the time of
exploitation, an attacker controlled buffer address is the first item on the
stack. By overwriting the function pointer list pointer address with the
address of an Import table, we can call any imported function. Our current
stack will be passed into the function for parameter use. as is. The first
item on our stack is an address that points to attacker-controlled data.

By overwriting the address, with the address of the
SetUnhandledExceptionFilter() IAT entry, execution will redirect into this
address when the default exception handler is called,

After returning from SetUnhandledExceptionFilter() PGP Outlook will fail as
it crawls back down the call stack, after cycling through the exception list
it will call the DefaultExceptionFilter, which now contains the address of
our code. This of course can also be exploited silently using frame
reconstruction.

Due to the large size of an example vulnerable email we are not including it
in our advisory. We will be updating the research section of our website
with a link to an example email. http://www.eEye.com

Where do you want your secret key to go today?

Vendor Status: NAI has worked quickly to safeguard customers against this
vulnerability. They have released a patch, for the latest versions of the
PGP Outlook plug-in, to protect systems from this flaw. You may download the
patch from:
http://www.nai.com/naicommon/download/upgrade/patches/patch-pgphotfix.asp
Note: This issue does not affect PGP Corporate Desktop users.

Discover: Marc Maiffret
Exploitation: Riley Hassell

Greetings: Kasia, and the hot photographer from Inc Magazine. Phil
Zimmerman, the godfather of personal privacy, much respect.

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