Necurs oddity II: avto111222@bigmir.net

Yesterday I saw a series spam emails from Necurs apparently attempting to collect replies to super.testtesttest2018@yahoo.com. Although that campaign is continuing today, a new spam run with similar characteristics has started this morning. For example:

From:    jKX Soto [ingmanz@redacted]
Reply-To:    jKX Soto [avto111222@bigmir.net]
Date:    19 July 2017 at 06:43
Subject:    CQJP

hDYNOX

TC

Subject, body text and vendor seem to be randomly generated. But in all cases, the Reply-To address is avto111222@bigmir.net (Bigmir is basically a Ukrainian version of Yahoo from what I can tell).

The purpose of this spam run is unclear, but spammers do sometimes launch probing attacks to see what kind of response they get from servers. This could be an attempt to clean up the Necurs email address database perhaps, perhaps for resale.