Code:
(
	SELECT
		MAX(x.id) MAX_ID_PER_ACC
	   FROM wfraud_data x
	  WHERE x.fraud_suspect_reason_id = 1761
	    AND x.time_created >= 1160463600
	    AND x.status ='N'
	    AND rownum < 2800
	    AND (x.expiration is null
	         OR x.expiration = 0
	         OR x.expiration > 1161003844
	         OR x.status != 'N'
	         OR BITAND(x.flags, 10) > 0)
	GROUP BY x.account_number
	) C
First check, would oracle materialize the in-line view?
Or post the execution plan.