installedSoftware = []

for key in reg:
    try:
        count = 0 # int variable for iterating through registry keys
        while True:
            subKeyName = EnumKey(key, count) # name of registry key at given index
            isKB = subKeyName.find('KB') # check if string contains KB number (-1 if not)
            if isKB != -1:
                keySplit = subKeyName.split('_') # split key name at underscores
                for s in keySplit:
                    if 'KB' in s:
                        installedSoftware.append(s) # add substring to list if it contains a KB number
            count += 1
    except WindowsError:
        pass

kbNumbers = set(installedSoftware)