oCERT Advisories

#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, patched in CVS

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 are released
2008-06-09: advisory release
2008-06-11: eCos patched in CVS

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

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