Onderwerp: [ GLSA 200411-01 ] ppp: Remote denial of service vulnerability

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Gentoo Linux Security Advisory GLSA 200411-01
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http://security.gentoo.org/
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Severity: Normal
Title: ppp: Remote denial of service vulnerability
Date: November 01, 2004
Bugs: #69152
ID: 200411-01

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Synopsis
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pppd contains a vulnerability that may allow an attacker to crash the
server.

Background
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ppp is a Unix implementation of the Point-to-Point Protocol.

Affected packages
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Package / Vulnerable / Unaffected
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1 net-dialup/ppp < 2.4.2-r7 >=3D 2.4.2-r7

Description
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The pppd server improperly verifies header fields, making it vulnerable
to denial of service attacks.

Impact
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An attacker can cause the pppd server to access memory that it isn't
allowed to, causing the server to crash. No code execution is possible
with this vulnerability, because no data is getting copied.

Workaround
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There is no known workaround at this time.

Resolution
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All ppp users should upgrade to the latest version:

# emerge --sync
# emerge --ask --oneshot --verbose ">=3Dnet-dialup/ppp-2.4.2-r7"

References
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[ 1 ] BugTraq Advisory
http://www.securityfocus.com/archive/1/379450

Availability
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This GLSA and any updates to it are available for viewing at
the Gentoo Security Website:

http://security.gentoo.org/glsa/glsa-200411-01.xml

Concerns?
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Security is a primary focus of Gentoo Linux and ensuring the
confidentiality and security of our users machines is of utmost
importance to us. Any security concerns should be addressed to
security@gentoo.org or alternatively, you may file a bug at
http://bugs.gentoo.org.

License
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Copyright 2004 Gentoo Foundation, Inc; referenced text
belongs to its owner(s).

The contents of this document are licensed under the
Creative Commons - Attribution / Share Alike license.

http://creativecommons.org/licenses/by-sa/1.0

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Luke Macken writes:

> The pppd server improperly verifies header fields, making it vulnerable
> to denial of service attacks.
>
> Impact
> ======
>
> An attacker can cause the pppd server to access memory that it isn't
> allowed to, causing the server to crash. No code execution is possible
> with this vulnerability, because no data is getting copied.

Furthermore, only the connection to the attacker will be affected,
since a separate pppd process handles each ppp connection. In other
words, an attacker can terminate their own connection, but they can
not affect any other connection, or prevent new connections from being
established. Given that, I don't think that this is even a DoS
vulnerability.

Paul.