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[oCERT-2008-006] multiple SNMP implementations HMAC authentication spoofing
2008/06/09 #2008-006 multiple SNMP implementations HMAC authentication spoofing
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.
Net-SNMP <= 5.4.1, <= 5.3.2, <= 5.2.4
UCD-SNMP, all versions
eCos, all versions
Net-SNMP >= 126.96.36.199, >= 188.8.131.52, >= 184.108.40.206
Credit: this issue was reported by CERT/CC, it is tracked as VU#878044.
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
Andrea Barisani | Founder & Project Coordinator
oCERT | Open Source Computer Emergency Response Team
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"Pluralitas non est ponenda sine necessitate"