MBAM is a teriffic program (I install it on every one of my machines & recommend it highly) but it alone cannot completely remove this malware. Poweliks is a malware with rootkit-like features, it resides in the registry (loads in memory) is persistent and is not present as a file which can be scanned & removed easily. The payload (malware file) is stored in an encrypted registry value and is loaded at boot time by a RUN key calling rundll32 process with an encrypted javascript payload. It has been seen to reside in (at least) these 2 keys:
HKCU\software\microsoft\windows\currentversion\run\(default)
HKEY_LOCAL_MACHINE\Software\classes\clsid\{73E709EA-5D93-4B2E-BBB0-99B7938DA9E4}\LocalServer32
Once the payload is loaded, it tries to execute an embedded powershell script in "interactive" (silent) mode. That powershell scripts contains another encoded payload which will be injected into a (legitimate) dllhost process (the persistent item), which acts as a trojan downloader for other malware& is also responsible for protecting the registry value by recreating it when removed.
RogueKiller (by French malware analyst Tigzy) claims to be able to remove Poweliks as does ESET Poweliks Cleaner & Malwarebytes Anti Rootkit Beta, links below.
http://www.adlice.com/poweliks-removal-with-roguekiller/
http://kb.eset.com/esetkb/index?page=content&id=SOLN3587
https://blog.malwarebytes.org/security-threat/2014/11/no-more-poweliks/
Me? I'd restore from backup if available or re-install the OS, YMMV.
Some interesting analyses:
https://blog.gdatasoftware.com/blog/article/poweliks-the-persistent-malware-without-a-file.html
http://www.kernelmode.info/forum/viewtopic.php?f=16&t=3377
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