diff --git a/base/univention-lib/debian/python-univention-lib.univention-config-registry-variables b/base/univention-lib/debian/python-univention-lib.univention-config-registry-variables
index 55bbbf791b..6b0857cc02 100644
--- a/base/univention-lib/debian/python-univention-lib.univention-config-registry-variables
+++ b/base/univention-lib/debian/python-univention-lib.univention-config-registry-variables
@@ -12,8 +12,8 @@ Type=str
 Categories=service-misc
 
 [listener/shares/whitelist/.*]
-Description[de]=Standardmäßig, wird die Erstellung von Freigaben in den meisten Verzeichnissen verhindert. Diese Variablen definieren eine Doppelpunkt-separierte Liste von erlaubten Verzeichnissen (z.B. /var:/usr).
-Description[en]=By default is is restricted to create shares in most directories for security reasons. These variables should contain a colon separated list of allowed directories (e.g. /var:/usr).
+Description[de]=Standardmäßig wird die Erstellung von Freigaben für einige Systemverzeichnisse verhindert. Diese Variablen ermöglichen das Freigeben von Verzeichnissen, die sonst auf der Standard-Blackist stehen. Die Werte der Variablen können eine durch Doppelpunkte separierte Liste von erlaubten Verzeichnissen enthalten (z.B. /var:/usr). Die Variable listener/shares/whitelist/default liefert eine empfohlene Standardliste für UCS.
+Description[en]=For security reasons creating shares for some system directories is denied by default. This family of variables allows overriding the default blacklist. The values may contain a colon separated list of allowed directories (e.g. /var:/usr). The variable listener/shares/whitelist/default specifies the UCS recommended default whitelist.
 Type=str
 Categories=service-misc
 
diff --git a/base/univention-lib/python/listenerSharePath.py b/base/univention-lib/python/listenerSharePath.py
index 5c28386c74..61f6845b45 100644
--- a/base/univention-lib/python/listenerSharePath.py
+++ b/base/univention-lib/python/listenerSharePath.py
@@ -37,24 +37,24 @@ import shutil
 
 DEFAULT_FS = "ext2/ext3:ext2:ext3:ext4:xfs:btrfs"
 DIR_BLACKLIST = []
+DIR_BLACKLIST.append("/bin")
 DIR_BLACKLIST.append("/boot")
-DIR_BLACKLIST.append("/sys")
-DIR_BLACKLIST.append("/proc")
-DIR_BLACKLIST.append("/etc")
 DIR_BLACKLIST.append("/dev")
-DIR_BLACKLIST.append("/tmp")
+DIR_BLACKLIST.append("/etc")
+DIR_BLACKLIST.append("/lib")
+DIR_BLACKLIST.append("/lib64")
+DIR_BLACKLIST.append("/proc")
 DIR_BLACKLIST.append("/root")
-DIR_BLACKLIST.append("/usr")
-DIR_BLACKLIST.append("/bin")
 DIR_BLACKLIST.append("/sbin")
+DIR_BLACKLIST.append("/sys")
+DIR_BLACKLIST.append("/tmp")
+DIR_BLACKLIST.append("/usr")
 DIR_BLACKLIST.append("/var")
-DIR_BLACKLIST.append("/lib")
-DIR_BLACKLIST.append("/lib64")
-# later on whitelisted:
+# whitelisted via UCR by default
 DIR_BLACKLIST.append("/home")
-DIR_BLACKLIST.append("/opt")
 DIR_BLACKLIST.append("/media")
 DIR_BLACKLIST.append("/mnt")
+DIR_BLACKLIST.append("/opt")
 DIR_BLACKLIST.append("/run")
 DIR_BLACKLIST.append("/srv")
 
diff --git a/services/univention-samba/samba-shares.py b/services/univention-samba/samba-shares.py
index 1f5f172ca7..33fed405d2 100644
--- a/services/univention-samba/samba-shares.py
+++ b/services/univention-samba/samba-shares.py
@@ -55,7 +55,7 @@ tmpFile = '/var/cache/univention-directory-listener/samba-shares.oldObject'
 
 
 def _validate_smb_share_name(name):
-	if len(name) > 80:
+	if not name or len(name) > 80:
 		return False
 	illegal_chars = set('\\/[]:|<>+=;,*?"' + ''.join(map(chr, range(0x1F + 1))))
 	if set(str(name)) & illegal_chars:
@@ -128,7 +128,8 @@ def handler(dn, new, old, command):
 		listener.unsetuid()
 
 	if old:
-		share_name_mapped = urllib.quote(old.get('univentionShareSambaName', [''])[0], safe='')
+		share_name = old.get('univentionShareSambaName', [''])[0]
+		share_name_mapped = urllib.quote(share_name, safe='')
 		filename = '/etc/samba/shares.conf.d/%s' % (share_name_mapped,)
 		listener.setuid(0)
 		try:
@@ -146,16 +147,16 @@ def handler(dn, new, old, command):
 		return (_quote(arg) for arg in args)
 
 	if new:
-		share_name = new['univentionShareSambaName'][0]
-		share_name_mapped = urllib.quote(share_name, safe='')
-		filename = '/etc/samba/shares.conf.d/%s' % (share_name_mapped,)
+		share_name = new.get('univentionShareSambaName', [''])[0]
 		if not _validate_smb_share_name(share_name):
 			univention.debug.debug(univention.debug.LISTENER, univention.debug.ERROR, "invalid samba share name: %r" % (share_name,))
 			return
+		share_name_mapped = urllib.quote(share_name, safe='')
+		filename = '/etc/samba/shares.conf.d/%s' % (share_name_mapped,)
 
 		# important!: createOrRename() checks if the share path is allowed. this must be done prior to writing any files.
 		# try to create directory to share
-		if new['univentionShareSambaName'][0] != 'homes':
+		if share_name != 'homes':
 			# object was renamed
 			if not old and oldObject and command == "a":
 				old = oldObject
@@ -173,7 +174,7 @@ def handler(dn, new, old, command):
 			fp = open(filename, 'w')
 
 			print >>fp, '[%s]' % (share_name,)
-			if new['univentionShareSambaName'][0] != 'homes':
+			if share_name != 'homes':
 				print >>fp, 'path = %s' % _quote(new['univentionSharePath'][0])
 			mapping = [
 				('description', 'comment'),
diff --git a/services/univention-samba4/samba-shares.py b/services/univention-samba4/samba-shares.py
index 622dfbdfb5..7a50f09551 100644
--- a/services/univention-samba4/samba-shares.py
+++ b/services/univention-samba4/samba-shares.py
@@ -55,7 +55,7 @@ tmpFile = '/var/cache/univention-directory-listener/samba-shares.oldObject'
 
 
 def _validate_smb_share_name(name):
-	if len(name) > 80:
+	if not name or len(name) > 80:
 		return False
 	illegal_chars = set('\\/[]:|<>+=;,*?"' + ''.join(map(chr, range(0x1F + 1))))
 	if set(str(name)) & illegal_chars:
@@ -128,7 +128,8 @@ def handler(dn, new, old, command):
 		listener.unsetuid()
 
 	if old:
-		share_name_mapped = urllib.quote(old.get('univentionShareSambaName', [''])[0], safe='')
+		share_name = old.get('univentionShareSambaName', [''])[0]
+		share_name_mapped = urllib.quote(share_name, safe='')
 		filename = '/etc/samba/shares.conf.d/%s' % (share_name_mapped,)
 		listener.setuid(0)
 		try:
@@ -147,15 +148,15 @@ def handler(dn, new, old, command):
 
 	if new:
 		share_name = new['univentionShareSambaName'][0]
-		share_name_mapped = urllib.quote(share_name, safe='')
-		filename = '/etc/samba/shares.conf.d/%s' % (share_name_mapped,)
 		if not _validate_smb_share_name(share_name):
 			univention.debug.debug(univention.debug.LISTENER, univention.debug.ERROR, "invalid samba share name: %r" % (share_name,))
 			return
+		share_name_mapped = urllib.quote(share_name, safe='')
+		filename = '/etc/samba/shares.conf.d/%s' % (share_name_mapped,)
 
 		# important!: createOrRename() checks if the share path is allowed. this must be done prior to writing any files.
 		# try to create directory to share
-		if new['univentionShareSambaName'][0] != 'homes':
+		if share_name != 'homes':
 			# object was renamed
 			if not old and oldObject and command == "a":
 				old = oldObject
@@ -173,7 +174,7 @@ def handler(dn, new, old, command):
 			fp = open(filename, 'w')
 
 			print >>fp, '[%s]' % (share_name,)
-			if new['univentionShareSambaName'][0] != 'homes':
+			if share_name != 'homes':
 				print >>fp, 'path = %s' % _quote(new['univentionSharePath'][0])
 			mapping = [
 				('description', 'comment'),