I wrote on blog on this baby here:
http://www.clientsfirst-us.com/blog/partners-perspective/urgent-cryptolocker-security-threat-possibly-worst-malware-ever/
SQL should be safe. Cryptolocker runs on the workstation and encrypts document type files that it can get to. This includes local, and anything that HAS A MAPPED DRIVE. UNC's are safe...for now... If for some stupid reason, the client has a mapped drive that can get direct access to the MDF sql files and they don't happen to be in use, then yes you are screwed.
It can't do anything to files that are in use either. It's critical that you have a backup or Disaster Recovery Solution that backs up 'point in time'. IE, cryptolocker hit at 11am, you restore all the files from 10am (assuming you have a system like
www.eversafe-backup.com that can take very frequent backups)
Some cheapo systems like Carbonite back the files up as they are changed so they are very nice about sending all your newly encrypted files to the cloud overwriting your good versions. Many of these online cloud backup services are NOT designed to let you restore every file from a point in time as they are backing them up as they change without a 'trigger point'
Cryptolocker, and its derivitives are detected about 75% of the time with current AV software, but its a moving target. There is just too much money to be made in this type of virus for it to not continue to be a problem for a LONG time.
Here are the file extensions currently affected.
3fr, accdb, ai, arw, bay, cdr, cer, cr2, crt, crw, dbf, dcr, der, dng, doc, docm, docx, dwg, dxf, dxg, eps, erf, indd, jpe, jpg, kdc, mdb, mdf, mef, mrw, nef, nrw, odb, odm, odp, ods, odt, orf, p12, p7b, p7c, pdd, pef, pem, pfx, ppt, pptm, pptx, psd, pst, ptx, r3d, raf, raw, rtf, rw2, rwl, srf, srw, wb2, wpd, wps, xlk, xls, xlsb, xlsm, xlsx