From ghudson@MIT.EDU Mon Nov 17 15:47:21 1997
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Date: Mon, 17 Nov 1997 15:47:18 -0500
From: ghudson@MIT.EDU
Reply-To: ghudson@MIT.EDU
To: krb5-bugs@MIT.EDU
Subject: for 1.0.3: kshd checksums
X-Send-Pr-Version: 3.99
System: SunOS small-gods 5.5.1 Generic_103640-12 sun4m sparc SUNW,SPARCstation-5
Architecture: sun4
krb5_checksum_ignored has changed several times, but it wound up
broken. According to Sam, the default behavior is supposed to be:
If an authenticator has a checksum, it is checked.
This way, if you always use checksums in your rsh requests, you're
okay, and if you have an old client, you're vulnerable to replay
attacks but you can still use kshd. Unfortunately, the default
behavior actuall is:
Checksums are never checked.
So unless you give kshd the -c option, you are vulnerable to replay
attacks even if clients are using perfectly good, checksummed
authenticators.
it do the right thing; this problem arose because people made careless
changes to security-critical logic.
Responsible-Changed-From-To: krb5-unassigned->tlyu
Responsible-Changed-By: tlyu
Responsible-Changed-When: Mon Nov 17 21:21:40 1997
Responsible-Changed-Why:
State-Changed-From-To: open-feedback
State-Changed-By: tlyu
State-Changed-When: Mon Nov 17 21:21:49 1997
State-Changed-Why:
Fixed:
src/appl/bsd/krshd.c 5.71
We might want to pull this into 1.0.3.
State-Changed-From-To: feedback-closed
State-Changed-By: tlyu
State-Changed-When: Mon Nov 17 21:56:27 1997
State-Changed-Why:
Checked in on release branch
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Message-Id: <199711172047.PAA20812@small-gods.MIT.EDU>
Date: Mon, 17 Nov 1997 15:47:18 -0500
From: ghudson@MIT.EDU
Reply-To: ghudson@MIT.EDU
To: krb5-bugs@MIT.EDU
Subject: for 1.0.3: kshd checksums
X-Send-Pr-Version: 3.99
Show quoted text
>Number: 500
>Category: krb5-appl
>Synopsis: for 1.0.3: kshd checksums
>Confidential: no
>Severity: serious
>Priority: high
>Responsible: tlyu
>State: closed
>Class: sw-bug
>Submitter-Id: unknown
>Arrival-Date: Mon Nov 17 15:48:01 EST 1997
>Last-Modified: Mon Nov 17 21:56:51 EST 1997
>Originator: Greg Hudson
>Organization:
MIT>Category: krb5-appl
>Synopsis: for 1.0.3: kshd checksums
>Confidential: no
>Severity: serious
>Priority: high
>Responsible: tlyu
>State: closed
>Class: sw-bug
>Submitter-Id: unknown
>Arrival-Date: Mon Nov 17 15:48:01 EST 1997
>Last-Modified: Mon Nov 17 21:56:51 EST 1997
>Originator: Greg Hudson
>Organization:
Show quoted text
>Release: 1.0
>Environment:
>Environment:
System: SunOS small-gods 5.5.1 Generic_103640-12 sun4m sparc SUNW,SPARCstation-5
Architecture: sun4
Show quoted text
>Description:
The logic surrounding krb5_checksum_required andkrb5_checksum_ignored has changed several times, but it wound up
broken. According to Sam, the default behavior is supposed to be:
If an authenticator has a checksum, it is checked.
This way, if you always use checksums in your rsh requests, you're
okay, and if you have an old client, you're vulnerable to replay
attacks but you can still use kshd. Unfortunately, the default
behavior actuall is:
Checksums are never checked.
So unless you give kshd the -c option, you are vulnerable to replay
attacks even if clients are using perfectly good, checksummed
authenticators.
Show quoted text
>How-To-Repeat:
>Fix:
None provided. Someone should look at the code *carefully*, and make>Fix:
it do the right thing; this problem arose because people made careless
changes to security-critical logic.
Show quoted text
>Audit-Trail:
Responsible-Changed-From-To: krb5-unassigned->tlyu
Responsible-Changed-By: tlyu
Responsible-Changed-When: Mon Nov 17 21:21:40 1997
Responsible-Changed-Why:
State-Changed-From-To: open-feedback
State-Changed-By: tlyu
State-Changed-When: Mon Nov 17 21:21:49 1997
State-Changed-Why:
Fixed:
src/appl/bsd/krshd.c 5.71
We might want to pull this into 1.0.3.
State-Changed-From-To: feedback-closed
State-Changed-By: tlyu
State-Changed-When: Mon Nov 17 21:56:27 1997
State-Changed-Why:
Checked in on release branch
Show quoted text
>Unformatted: