http://dhc014.rpc1.org/indexOEM.htm#S According to this, it's an OEM version of the LTC-48161H - known firmware KYS2 - Dated "Jun27 ,2003"
Latest possible firmware would seem to be:
Crossflash to speed-patched Liteon KH0R
NB. This will void your warranty, and the change to Liteon identity may also void bundled software