diff --git a/bin/kali-finish-install b/bin/kali-finish-install
new file mode 100755
index 0000000..9456690
--- /dev/null
+++ b/bin/kali-finish-install
@@ -0,0 +1,66 @@
+#!/bin/sh
+
+# The reference version of this script is maintained in
+# live-build-config/bin/kali-finish-install.
+#
+# It is used in multiple places to finish configuring the target system
+# and build.sh copies it where required (in the simple-cdd configuration
+# and in the live-build configuration).
+
+configure_sources_list() {
+    if grep -q '^deb ' /etc/apt/sources.list; then
+	echo "INFO: sources.list is configured, everything is fine"
+	return
+    fi
+
+    echo "INFO: sources.list is empty, setting up a default one for Kali"
+
+    cat >/etc/apt/sources.list <<END
+# See https://www.kali.org/docs/general-use/kali-linux-sources-list-repositories/
+deb http://http.kali.org/kali kali-rolling main contrib non-free
+
+# Additional line for source packages
+# deb-src http://http.kali.org/kali kali-rolling main contrib non-free
+END
+    apt-get update
+}
+
+get_user_list() {
+    for user in $(cd /home && ls); do
+	if ! getent passwd "$user" >/dev/null; then
+	    echo "WARNING: user '$user' is invalid but /home/$user exists"
+	    continue
+	fi
+	echo "$user"
+    done
+}
+
+configure_zsh() {
+    if grep -q 'nozsh' /proc/cmdline; then
+	echo "INFO: user opted out of zsh by default"
+	return
+    fi
+    if [ ! -x /usr/bin/zsh ]; then
+	echo "INFO: /usr/bin/zsh is not available"
+	return
+    fi
+    for user in $(get_user_list); do
+	echo "INFO: changing default shell of user '$user' to zsh"
+	chsh --shell /usr/bin/zsh $user
+    done
+}
+
+configure_kaboxer() {
+    # Create the group if needed
+    addgroup --system kaboxer || true
+
+    # Add the users to the group
+    for user in $(get_user_list); do
+	echo "INFO: adding user '$user' to group 'kaboxer'"
+	adduser $user kaboxer || true
+    done
+}
+
+configure_sources_list
+configure_zsh
+configure_kaboxer
diff --git a/build.sh b/build.sh
index 6757644..f61b03c 100755
--- a/build.sh
+++ b/build.sh
@@ -212,6 +212,7 @@ case "$IMAGE_TYPE" in
 		if [ "$NO_CLEAN" = "" ]; then
 			run_and_log $SUDO lb clean --purge
 		fi
+		cp bin/kali-finish-install kali-config/common/includes.installer/
 		[ $? -eq 0 ] || failure
 		run_and_log lb config -a $KALI_ARCH $KALI_CONFIG_OPTS "$@"
 		[ $? -eq 0 ] || failure
@@ -259,6 +260,9 @@ case "$IMAGE_TYPE" in
 		# Tasksel is required in the mirror for debian-cd
 		echo tasksel >>simple-cdd/profiles/kali.downloads
 
+		# Update the postinst script
+		cp bin/kali-finish-install simple-cdd/profiles/kali.postinst
+
 		# Run simple-cdd
 		cd simple-cdd
 		run_and_log build-simple-cdd \
diff --git a/kali-config/common/includes.installer/kali-finish-install b/kali-config/common/includes.installer/kali-finish-install
new file mode 100755
index 0000000..9456690
--- /dev/null
+++ b/kali-config/common/includes.installer/kali-finish-install
@@ -0,0 +1,66 @@
+#!/bin/sh
+
+# The reference version of this script is maintained in
+# live-build-config/bin/kali-finish-install.
+#
+# It is used in multiple places to finish configuring the target system
+# and build.sh copies it where required (in the simple-cdd configuration
+# and in the live-build configuration).
+
+configure_sources_list() {
+    if grep -q '^deb ' /etc/apt/sources.list; then
+	echo "INFO: sources.list is configured, everything is fine"
+	return
+    fi
+
+    echo "INFO: sources.list is empty, setting up a default one for Kali"
+
+    cat >/etc/apt/sources.list <<END
+# See https://www.kali.org/docs/general-use/kali-linux-sources-list-repositories/
+deb http://http.kali.org/kali kali-rolling main contrib non-free
+
+# Additional line for source packages
+# deb-src http://http.kali.org/kali kali-rolling main contrib non-free
+END
+    apt-get update
+}
+
+get_user_list() {
+    for user in $(cd /home && ls); do
+	if ! getent passwd "$user" >/dev/null; then
+	    echo "WARNING: user '$user' is invalid but /home/$user exists"
+	    continue
+	fi
+	echo "$user"
+    done
+}
+
+configure_zsh() {
+    if grep -q 'nozsh' /proc/cmdline; then
+	echo "INFO: user opted out of zsh by default"
+	return
+    fi
+    if [ ! -x /usr/bin/zsh ]; then
+	echo "INFO: /usr/bin/zsh is not available"
+	return
+    fi
+    for user in $(get_user_list); do
+	echo "INFO: changing default shell of user '$user' to zsh"
+	chsh --shell /usr/bin/zsh $user
+    done
+}
+
+configure_kaboxer() {
+    # Create the group if needed
+    addgroup --system kaboxer || true
+
+    # Add the users to the group
+    for user in $(get_user_list); do
+	echo "INFO: adding user '$user' to group 'kaboxer'"
+	adduser $user kaboxer || true
+    done
+}
+
+configure_sources_list
+configure_zsh
+configure_kaboxer
diff --git a/kali-config/common/includes.installer/usr/lib/finish-install.d/14fix-kali-sources-list b/kali-config/common/includes.installer/usr/lib/finish-install.d/14fix-kali-sources-list
deleted file mode 100755
index 9c8a04a..0000000
--- a/kali-config/common/includes.installer/usr/lib/finish-install.d/14fix-kali-sources-list
+++ /dev/null
@@ -1,17 +0,0 @@
-#!/bin/sh
-
-if grep -q '^deb ' /target/etc/apt/sources.list; then
-    echo "INFO: sources.list is configured, everything is fine"
-    exit 0
-fi
-
-echo "INFO: sources.list is empty, setting up a default one for Kali"
-
-cat >/target/etc/apt/sources.list <<END
-# See https://www.kali.org/docs/general-use/kali-linux-sources-list-repositories/
-deb http://http.kali.org/kali kali-rolling main contrib non-free
-
-# Additional line for source packages
-# deb-src http://http.kali.org/kali kali-rolling main contrib non-free
-END
-in-target apt-get update || true
diff --git a/kali-config/common/includes.installer/usr/lib/finish-install.d/14kali-finish-install b/kali-config/common/includes.installer/usr/lib/finish-install.d/14kali-finish-install
new file mode 100755
index 0000000..67f541e
--- /dev/null
+++ b/kali-config/common/includes.installer/usr/lib/finish-install.d/14kali-finish-install
@@ -0,0 +1,6 @@
+#!/bin/sh
+
+# Run the kali-finish-install script to configure the target system
+cp /kali-finish-install /target/
+in-target /kali-finish-install || true
+rm -f /target/kali-finish-install
diff --git a/simple-cdd/profiles/kali.postinst b/simple-cdd/profiles/kali.postinst
index ee3d72c..9456690 100755
--- a/simple-cdd/profiles/kali.postinst
+++ b/simple-cdd/profiles/kali.postinst
@@ -1,5 +1,12 @@
 #!/bin/sh
 
+# The reference version of this script is maintained in
+# live-build-config/bin/kali-finish-install.
+#
+# It is used in multiple places to finish configuring the target system
+# and build.sh copies it where required (in the simple-cdd configuration
+# and in the live-build configuration).
+
 configure_sources_list() {
     if grep -q '^deb ' /etc/apt/sources.list; then
 	echo "INFO: sources.list is configured, everything is fine"