[oCERT-2008-006] multiple SNMP implementations HMAC authenticationspoofing Jun 09 2008 11:06PM
Andrea Barisani (lcars ocert org)

2008/06/09 #2008-006 multiple SNMP implementations HMAC authentication spoofing

Description:

Some SNMP implementations include incomplete HMAC authentication code that
allows spoofing of authenticated SNMPv3 packets.

The authentication code reads the length to be checked from sender input,
this allows the sender to supply single byte HMAC code and have a 1 in 256
chance of matching the correct HMAC and authenticating, as only the first
byte will be checked. The sender would need to know a valid username.

Currently Net-SNMP and UCD-SNMP are known to be vulnerable, other SNMP
implementations may also be affected. The eCos project includes code derived
from UCD-SNMP and is therefore also affected.

Affected version:

Net-SNMP <= 5.4.1, <= 5.3.2, <= 5.2.4
UCD-SNMP, all versions
eCos, all versions

Fixed version:

Net-SNMP >= 5.4.1.1, >= 5.3.2.1, >= 5.2.4.1
UCD-SNMP, N/A
eCos, N/A

Credit: this issue was reported by CERT/CC, it is tracked as VU#878044.

CVE: CVE-2008-0960

Timeline:
2008-06-05: CERT/CC reports VU#878044 to oCERT requesting joint coordination
2008-06-05: contacted affected vendors
2008-06-06: added eCos to affected packages
2008-06-09: patched net-snmp packages released
2008-06-09: advisory release

References:
http://sourceforge.net/forum/forum.php?forum_id=833770
http://sourceforge.net/tracker/index.php?func=detail&aid=1989089&group_i
d=12694&atid=456380
http://www.kb.cert.org/vuls/id/878044

Links:
http://www.net-snmp.org
http://www.ece.ucdavis.edu/ucd-snmp
http://ecos.sourceware.org

Permalink:
http://www.ocert.org/advisories/ocert-2008-006.html

--
Andrea Barisani | Founder & Project Coordinator
oCERT | Open Source Computer Emergency Response Team

<lcars (at) ocert (dot) org [email concealed]> http://www.ocert.org
0x864C9B9E 0A76 074A 02CD E989 CE7F AC3F DA47 578E 864C 9B9E
"Pluralitas non est ponenda sine necessitate"

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