Bye Empire, Hello Nebula Exploit Kit.

Earlier that same day, colleagues at Trendmicro told me they were seeing activity from a group we are following under the name "GamiNook" (illustration coming later) in Japan redirecting traffic to a variation of Sundown.

Note: to be sure that the payload difference is tied to Geo and not time based (rotation or operator changing it ) you need to make at least a third pass with first Geo and ensure dropped sample is identical as in first pass.

At that point you can only suspect this Sundown variant might be Nebula (even if clues are multiple, a funny one being that the traffic illustrated in the advert thread is quite inline with the one captured in France).

So I was naming that variation: Sundown-N. Intel shared by Frank Ruiz (FoxIT) on the 21st allowed me to know for sure this traffic was indeed Nebula.

The following days i saw other actor sending traffic to this EK.

Today URI pattern changed from this morning :

(which is Sundown/Beps without the index.php) to

This landing pattern change triggered the publication of this post. Nebula might end up not being a "vapor" EK but let's wait and see. The only difference with Sundown till today was its internal TDS.

Exploits (medium confidence - might be updated ):

CVE-2014-6332 + CVE-2015-0016

CVE-2016-0189 godmode

CVE-2014-8439

CVE-2015-7645

CVE-2016-4117

Thanks Joseph C Chen (Trendmicro),  Frank Ruiz (Fox-IT InTELL) and Andrew Komarov ( InfoArmor Inc. ) for the help on different aspect of this post.

Some IOCs