GPG 1.0.3 doesn't detect modifications to files with multiple signatures

Elias Levy aleph1 at securityfocus.com
Thu Oct 12 12:18:54 CEST 2000


I've verifid the message seems to be correct using gpg (GnuPG) 1.0.3.

Date: Wed, 11 Oct 2000 12:30:19 -0700
Message-Id: <200010111930.MAA03505 at mail14.bigmailbox.com>
From: "Jim Small" <cavenewt at my-deja.com>
To: bugtraq at securityfocus.com
Subject: GPG 1.0.3 doesn't detect modifications to files with multiple
    signatures

Attached is multiple copies of a file I had signed.  Then I started modifying parts of the SIGNED message.  To see if gpg could detect that the messages had been altered.  It did not detect them, so long as the last signed message had not been altered.

Save this message as newfile.asc and run
gpg --verify newfile.asc -o /dev/null
to see for yourself  (the key it was signed with is available via keyservers)
 
 
asdfasfasdfd
 
 
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
 
I just added by one stuff to thie message
bogugfirst file encrypted with nobody dude on uinix box, send to nethole forpmail
 
this is actually encrypted with a valid pgpg key imported form win95 
 
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.3 (GNU/Linux)
Comment: For info see http://www.gnupg.org
 
iD8DBQE538QlZi9y1BQncn4RAj/vAKCmfScBFegl6LMD3Q99N51pvuHAIQCfUv5+ a05Yt6xZwd/PxtQsRe+88AQ=
=siBR
-----END PGP SIGNATURE-----
 
middle stuff
 
 
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
 
another wrong
first file encrypted with nobody dude on uinix box, send to nethole forpmail
 
this is actually encrypted with a valid pgpg key imported form win95 
 
another file
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.3 (GNU/Linux)
Comment: For info see http://www.gnupg.org
 
iD8DBQE538hvZi9y1BQncn4RAolnAKCwEJTyPm6895ybQfk1D5IfeqJjmwCg4MlP 3NbvJocg5ksql40aOTZf0MY=
=yBf2
-----END PGP SIGNATURE-----
 
 
 
asfasfasf end stuff
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
 
first file encrypted with nobody dude on uinix box, send to nethole forpmail
 
this is actually encrypted with a valid pgpg key imported form win95 
 
bogud
 
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.3 (GNU/Linux)
Comment: For info see http://www.gnupg.org
 
iD8DBQE538QlZi9y1BQncn4RAj/vAKCmfScBFegl6LMD3Q99N51pvuHAIQCfUv5+ a05Yt6xZwd/PxtQsRe+88AQ=
=siBR
-----END PGP SIGNATURE-----
 
stuff
 
 
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
 
first file encrypted with nobody dude on uinix box, send to nethole forpmail
 
 
 
this is actually encrypted with a valid pgpg key imported form win95 
 
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.3 (GNU/Linux)
Comment: For info see http://www.gnupg.org
 
iD8DBQE538QlZi9y1BQncn4RAj/vAKCmfScBFegl6LMD3Q99N51pvuHAIQCfUv5+ a05Yt6xZwd/PxtQsRe+88AQ=
=siBR
-----END PGP SIGNATURE-----
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
 
first file encrypted with nobody dude on uinix box, send to nethole forpmail
 
this is actually encrypted with a valid pgpg key imported form win95 
 
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.3 (GNU/Linux)
Comment: For info see http://www.gnupg.org
 
iD8DBQE538QlZi9y1BQncn4RAj/vAKCmfScBFegl6LMD3Q99N51pvuHAIQCfUv5+ a05Yt6xZwd/PxtQsRe+88AQ=
=siBR
-----END PGP SIGNATURE-----
gpg: Signature made Sat Oct  7 17:47:33 2000 PDT using DSA key ID 1427727E
gpg: Good signature from "James F. Small, Jr. <smallj at nethole.com>" gpg:                aka "Jim Small <smallj at pacbell.net>" gpg:                aka "James F. Small, Jr. <smallj at saic.com>" gpg:                aka "James F. Small, Jr. <smallj at small.cx>" gpg: Signature made Sat Oct  7 18:05:51 2000 PDT using DSA key ID 1427727E
gpg: BAD signature from "James F. Small, Jr. <smallj at nethole.com>" gpg: Signature made Sat Oct  7 17:47:33 2000 PDT using DSA key ID 1427727E
gpg: Good signature from "James F. Small, Jr. <smallj at nethole.com>" gpg:                aka "Jim Small <smallj at pacbell.net>" gpg:                aka "James F. Small, Jr. <smallj at saic.com>" gpg:                aka "James F. Small, Jr. <smallj at small.cx>" gpg: Signature made Sat Oct  7 17:47:33 2000 PDT using DSA key ID 1427727E
gpg: Good signature from "James F. Small, Jr. <smallj at nethole.com>" gpg:                aka "Jim Small <smallj at pacbell.net>" gpg:                aka "James F. Small, Jr. <smallj at saic.com>" gpg:                aka "James F. Small, Jr. <smallj at small.cx>" gpg: Signature made Sat Oct  7 17:47:33 2000 PDT using DSA key ID 1427727E
gpg: Good signature from "James F. Small, Jr. <smallj at nethole.com>" gpg:                aka "Jim Small <smallj at pacbell.net>" gpg:                aka "James F. Small, Jr. <smallj at saic.com>" gpg:                aka "James F. Small, Jr. <smallj at small.cx>" 
 
 




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-- 
Elias Levy
SecurityFocus.com
http://www.securityfocus.com/
Si vis pacem, para bellum



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