Foundstone Labs Advisory - Remotely Exploitable Buffer Overflow in PGP

[Foundstone Labs]

Foundstone Labs Advisory - 090502-PCRO

Advisory Name:	Remotely Exploitable Buffer Overflow in PGP
 Release Date:	September 5, 2002
  Application:	PGP Corporate Desktop 7.1.1
    Platforms:	Windows 2000/XP
     Severity:	Remote code execution and plaintext passphrase
disclosure
      Vendors:	PGP Corporation (http://www.pgp.com)
      Authors:	Tony Bettini (tony.bettini at foundstone.com)
CVE Candidate:	CAN-2002-0850
    Reference:	http://www.foundstone.com/advisories

Overview:

In many locations where PGP handles files, the length of the filename is
not
properly checked. As a result, PGP Corporate Desktop will crash if a
user
attempts to encrypt or decrypt a file with a long filename. A remote
attacker
may create an encrypted document, that when decrypted by a user running
PGP,
would allow for remote commands to be executed on the client's computer.

Detailed Description:

A malicious attacker could create a filename containing:
<196 bytes><eip><9 bytes><readable address><29 bytes>

The attacker would then encrypt the file using the public key of the
target user. In many cases, public keys often contain banners of the
utilized PGP client software and its associated version.

The encrypted archive could then be sent to the target user; potentially
via a Microsoft Outlook attachment. The email attachment could have a 
filename such as "foryoureyesonly.pgp" or "confidential.pgp". When the
unsuspecting user decrypts the archive (either via autodecrypt or
manual), the
overflow will occur if the file within the archive has a long filename.

In some cases the attacker may also obtain the passphrase of the target
user.
PGP crashes immediately after the decryption of the malicious file and
before
the memory containing the passphrase is overwritten.

Vendor Response:

PGP has issued a fix for this vulnerability, it is available at:
http://www.nai.com/naicommon/download/upgrade/patches/patch-pgphotfix.as
p

Foundstone would like to thank PGP for their cooperation with the
remediation
of this vulnerability.

Solution:

We recommend applying the vendor patch.

Disclaimer:

The information contained in this advisory is copyright (c) 2002 
Foundstone, Inc. and is believed to be accurate at the time of 
publishing, but no representation of any warranty is given, 
express, or implied as to its accuracy or completeness. In no 
event shall the author or Foundstone be liable for any direct, 
indirect, incidental, special, exemplary or consequential 
damages resulting from the use or misuse of this information.  
This advisory may be redistributed, provided that no fee is 
assigned and that the advisory is not modified in any way.

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