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AUSCERT External Security Bulletin Redistribution
ESB-2002.329 -- AIX Security Alert Summary
OpenSSH Vulnerabilities in Challenge Response Handling
3 July 2002
AusCERT Security Bulletin Summary
Product: OpenSSH 2.3.1p1 to 3.3
Operating System: AIX with the Linux Affinity Toolkit
Impact: Root Compromise
Execute Arbitrary Code/Commands
Denial of Service
Access Required: Remote
Comments: This advisory contains the response from IBM on the recent
OpenSSH Vulnerabilities. It is an update to the summary
information provided in ESB-2002.291.
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This file contains summary information on AIX security alerts published
by the Computer Emergency Response Team (CERT), and the IBM Emergency
Response Team (ERS). The full text of these alerts can be obtained from
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The fixes mentioned in this document, when available, can be obtained
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The 'Security_APARs' document on this mail server contains a list of
security related APARs.
CERT Advisory CA-2002-18 OpenSSH Vulnerabilities in Challenge Response
There are two related vulnerabilities in the challenge response
handling code in OpenSSH versions 2.3.1p1 through 3.3. They may allow
a remote intruder to execute arbitrary code as the user running sshd
(often root). The first vulnerability affects OpenSSH versions 2.9.9
through 3.3 that have the challenge response option enabled and that
use SKEY or BSD_AUTH authentication. The second vulnerability affects
PAM modules using interactive keyboard authentication in OpenSSH
versions 2.3.1p1 through 3.3, regardless of the challenge response
option setting. Additionally, a number of other possible security
problems have been corrected in OpenSSH version 3.4.
IBM's AIX operating system does not ship with OpenSSH; however,
OpenSSH is available for installation on AIX via the Linux Affinity
Toolkit. The version included on the CD containing the Toolkit is
vulnerable to the latest discovered vulnerability discussed here as is
the version of OpenSSH available for downloading from the IBM Linux
Affinity website. Anyone running this version is advised to follow the
recommendations above to limit their vulnerability.
We working with the changes for version 3.4 and will have a new
package availble for download as soon as possible. When available the
new packages can be downloaded from:
This site contains Linux Affinity applications containing
cryptographic algorithms, and new users of this site are asked to
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