A Malwarebytes v3.2.2 Threat Scan (database v1.0.3104) flagged registry entries associated with my IE9 browser today for PUP.Optional.ASK. I don't normally use IE9 (my default browser is currently FF ESR v52.4.0) but I suspect MB incorrectly detected registry entries for Norton Safe Search (a feature bundled with my Norton Toolbar v2015.12.0.5) as PUP.Optional.Ask, since Norton Safe Search uses the Ask.com search engine.
Here's the scan log: MB v3_2_2 Threat Scan PUP_Optional_ASK 26 Oct 2017.txt
Registry Key: 1
PUP.Optional.ASK, HKU\S-1-5-21-3086198521-800258848-3831315664-1001\SOFTWARE\MICROSOFT\INTERNET EXPLORER\SEARCHSCOPES\{104390CA-E40C-43BF-A771-26DE9E4121CC}, No Action By User, [525], [450494],1.0.3104
Registry Value: 1
PUP.Optional.ASK, HKU\S-1-5-21-3086198521-800258848-3831315664-1001\SOFTWARE\MICROSOFT\INTERNET EXPLORER\SEARCHSCOPES\{104390CA-E40C-43BF-A771-26DE9E4121CC}|URL, No Action By User, [525], [450494],1.0.3104
---------- 32-bit Vista Home Premium SP2 * NS Premium v22.11.0.41 * Firefox ESR v52.4.0 * IE9 * MB Premium v3.2.2.2018-1.0.212