OSEC

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From: Foundstone Labs (labs_at_foundstone.com)
Date: Thu Sep 05 2002 - 14:05:36 CDT

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    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.bettinifoundstone.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 it's associated version. This means
    an attacker could poll a PGP key server to find, with a
    reasonable level of accuracy, a large list of vulnerable clients.

    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.