Hi Stephen.
I doubt you could "trap" it, but you may be able to poll the ENTITY-MIB if you are running SW version 7.0 or later on the ASA. Please see the following document of the supported MIBs in the ASA:
http://www.cisco.com/en/US/products/hw/vpndevc/ps2030/products_tech_note09186a0080094a13.shtml#mibsupportbyversion
As mentioned, I suspect the ENTITY-MIB is what you'll need to poll, and specificly this object:
.1.3.6.1.2.1.47.1.1.1.1.10
entPhysicalSoftwareRev OBJECT-TYPE
-- FROM ENTITY-MIB
-- TEXTUAL CONVENTION SnmpAdminString
SYNTAX OCTET STRING (0..255)
DISPLAY-HINT "255a"
MAX-ACCESS read-only
STATUS Current
DESCRIPTION "The vendor-specific software revision string for the
physical entity.
Note that if revision information is stored internally in a
non-printable (e.g., binary) format, then the agent must
convert such information to a printable format, in an
implementation-specific manner.
If no specific software programs are associated with the
physical component, or this information is unknown to the
agent, then this object will contain a zero-length string."
::= { iso(1) org(3) dod(6) internet(1) mgmt(2) mib-2(1) entityMIB(47) entityMIBObjects(1) entityPhysical(1) entPhysicalTable(1) entPhysicalEntry(1) 10 }
Good Luck!
-Joe
