Update cobalt.txt
Update cobalt.txt

[0] https://www.proofpoint.com/us/threat-insight/post/new-modular-downloaders-fingerprint-systems-part-3-cobint

Have updated trail due to ```the C&C host and URI were “rietumu[.]me” and “xaczkajeieypiarll” respectively.``` snippet and ```Figure 4: Stage 1 HTTPS request```
stamparm/maltrail,stamparm/maltrail,stamparm/maltrail,stamparm/maltrail