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TITLE:
Net-SNMP HMAC Authentication Spoofing Vulnerability

SECUNIA ADVISORY ID:
SA30574

VERIFY ADVISORY:
http://secunia.com/advisories/30574/

CRITICAL:
Less critical

IMPACT:
Spoofing

WHERE:
>From local network

SOFTWARE:
Net-snmp 5.x
http://secunia.com/product/419/

DESCRIPTION:
A vulnerability has been reported in Net-SNMP, which can be exploited
by malicious people to spoof authenticated SNMPv3 packets.

The vulnerability is caused due to an error within the verification
of the HMAC digest. This can be exploited to increase the chance of
successfully spoofing a packet to 1 in 256 by sending a specially
crafted SNMPv3 packet with an incomplete 1 byte HMAC digest.

Successful exploitation requires a valid username.

The vulnerability is reported in versions prior to 5.4.1.1 of the
5.4.x branch, 5.3.2.1 of the 5.3.x branch, and 5.2.4.1 of the 5.2.x
branch.

SOLUTION:
Update to version 5.4.1.1, 5.3.2.1, or 5.2.4.1.

PROVIDED AND/OR DISCOVERED BY:
oCERT credits CERT/CC.

ORIGINAL ADVISORY:
Net-SNMP:
http://sourceforge.net/forum/forum.php?forum_id=833770

US-CERT VU#878044:
http://www.kb.cert.org/vuls/id/878044

OTHER REFERENCES:
oCERT:
http://www.ocert.org/advisories/ocert-2008-006.html

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About:
This Advisory was delivered by Secunia as a free service to help
everybody keeping their systems up to date against the latest
vulnerabilities.

Subscribe:
http://secunia.com/secunia_security_advisories/

Definitions: (Criticality, Where etc.)
http://secunia.com/about_secunia_advisories/


Please Note:
Secunia recommends that you verify all advisories you receive by
clicking the link.
Secunia NEVER sends attached files with advisories.
Secunia does not advise people to install third party patches, only
use those supplied by the vendor.

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