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OpenSSH "buffer_append_space()" Buffer Management Vulnerability
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Secunia Advisory:
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SA9743
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Release Date:
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2003-09-16
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Last Update:
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2003-09-17
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Popularity:
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15,965 views
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Critical:
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Highly critical
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Impact:
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DoS
System access
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Where:
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From remote
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Solution Status:
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Vendor Patch
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| Software: | OpenSSH 3.x
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| CVE reference: | CVE-2003-0693
CVE-2003-0695
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Description:
A vulnerability has been reported in OpenSSH, which potentially can be exploited by malicious people to cause a DoS (Denial of Service) or compromise a vulnerable system.
The vulnerability is caused due to a buffer management error in the "buffer_append_space()" function. When OpenSSH receives a packet that is larger than the remaining free space and fails the range check when trying to reallocate a larger buffer, the "fatal()" function is called.
In some circumstances the function may attempt to free memory outside the allocated buffer, which leads to heap corruption. However, it is currently not fully known whether the vulnerability is exploitable or not.
All versions prior to 3.7.1 are vulnerable.
NOTE: This advisory will be updated when more information is available.
Solution:
Update to version 3.7.1:
http://openssh.org/
Restrict access to the SSH service (port 22/tcp) allowing only trusted systems to connect.
Changelog:
2003-09-16: Added CVE reference, link to original advisory and link to CERT vulnerability note. Updated "Description" section.
2003-09-17: Updated vulnerable versions. Openssh.org has changed their advisory to include 3.7 as vulnerable.
2003-09-17: Added links to announcement mails in other references section.
Original Advisory:
http://www.openssh.com/txt/buffer.adv
Other References:
CERT vulnerability note VU#333628:
http://www.kb.cert.org/vuls/id/333628
CERT Advisory CA-2003-24:
http://www.cert.org/advisories/CA-2003-24.html
Information about 3.7 release:
http://www.mindrot.org/pipermail/open...x-announce/2003-September/000063.html
Information about 3.7.1 release:
http://www.mindrot.org/pipermail/open...x-announce/2003-September/000064.html
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About this Secunia Advisory
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Please note: The information that this Secunia Advisory is based on comes from a third party unless stated otherwise.
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