K-070: PGP Additional Decryption Keys (ADKs) Vulnerability

PROBLEM:       An implementation flaw allows unsigned Additional Decryption
               Keys (ADKs) to be added to a certificate and used for
               encryption.
PLATFORM:      Those running PGP versions 5.5.x through 6.5.3, both domestic
               and international.
DAMAGE:        The attacker who inserted the unsigned ADK can decrypt messages
               that were later encrypted using the altered certificate.
SOLUTION:      It is up to the sender to verify that the certificate that is
               used for encryption does not contain any unsigned ADKs. Network
               Associates, Inc. has released many product updates and HotFixes
               for this problem. Apply the appropriate update and/or HotFix.
VULNERABILITY  The risk is MEDIUM. The vulnerability is difficult to exploit.
ASSESSMENT:


[ Start Network Associates, Inc. Advisory ]

PGP ADK Security Advisory

On the morning of Thursday, August 24, researchers in Germany
announced the discovery of a bug in PGP versions 5.5 through 6.5.3,
regarding how those versions handle unauthorized Additional
Decryption Key (ADK) additions to the unhashed/unsigned areas of PGP
keys. This page provides the most up-to-date information regarding
this issue and what steps Network Associates is taking. Please refer
back to this page in the future for updates.

As reported in the CERT advisory, exploitation of this bug is
unlikely due to the unique circumstances under which an attack could
be launched. To date, there have been no reported exploits.

WHAT'S NEW

Network Associates performed a thorough inspection of the world's
largest public PGP keyserver (certserver.pgp.com), containing nearly
1.2 million PGP keys, and found that no keys contained on the server
were affected by this issue.


A software update has been applied to certserver.pgp.com and
pgpkeys.mit.edu which automatically cleanses keys as they are
uploaded to the servers. The cleansing process removes any
signatures that have been tampered with (containing offending
unhashed subpackets). A HotFix for PGP Certificate Server customers
will be released soon that contains this update. Network Associates
strongly recommends that customers download and install this HotFix
on their PGP Certificate Servers as soon as it is available.


We have released a new command line utility, PGPrepair 1.0, that
will scan PGP keyrings and look for (and can repair) keys that have
been tampered with. This utility is available on Windows, Solaris
and Linux platforms. The PGPrepair tool is designed to repair
keyrings created and/or used by PGP versions 2.6.2 and above. It can
be applied to personal keyrings or to large keyserver keyrings
(including PGP Certificate Servers).


We have also released many product updates and HotFixes which
resolve this issue. For more information about which versions of PGP
are affected by this issue, what product updates/HotFixes are
available and what we recommend you do regarding this issue, please
visit the PGP Product Information Center for the ADK
Security-Related Bug.


Network Associates/PGP Security plans to release a detailed, formal
advisory about this issue in the near future.

(C) 2000, Network Associates, Inc. and its affiliated Companies. All
Rights Reserved.

[ End Network Associates, Inc. Advisory ]

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