diff --git a/src/uds/core/util/auth.py b/src/uds/core/util/auth.py
index f8b1ea19a..27b04ab58 100644
--- a/src/uds/core/util/auth.py
+++ b/src/uds/core/util/auth.py
@@ -108,8 +108,10 @@ def get_attributes_regex_field(field: "ui.gui.TextField|str") -> set[str]:
         # If attributes concateated with +, add all
         if "+" in attr:
             res.update(attr.split("+"))
-        elif ":" in attr:  # lower precedence than +
-            res.add(attr.split(":")[0])
+        elif "**" in attr:  # lower precedence than +; "attr**prefix" — request the actual attribute
+            res.add(attr.split("**", 1)[0])
+        elif ":" in attr:  # lower precedence than +; "prefix:attr" — request the actual attribute
+            res.add(attr.split(":", 1)[1])
         else:  # If not, add the attribute
             res.add(attr)
 
@@ -145,6 +147,10 @@ def _get_attr(attr_name: str) -> list[str]:
                     # Prepend the value after ** to attribute value before **
                     attr, prependable = attr_name.split("**")
                     val = [prependable + a for a in ensure.as_list(attributes.get(attr, []))]
+                elif ":" in attr_name:
+                    # "prefix:attr" — look up attr, prepend prefix to each value (e.g. alumno:alum + "S" -> "alumnoS")
+                    prefix, attr = attr_name.split(":", 1)
+                    val = [prefix + a for a in ensure.as_list(attributes.get(attr, []))]
                 else:
                     val = ensure.as_list(attributes.get(attr_name, []))
                 return val
diff --git a/tests/core/util/test_auth_regex.py b/tests/core/util/test_auth_regex.py
new file mode 100644
index 000000000..0760ebb6a
--- /dev/null
+++ b/tests/core/util/test_auth_regex.py
@@ -0,0 +1,60 @@
+# -*- coding: utf-8 -*-
+from tests.utils.test import UDSTestCase
+
+
+class TestProcessRegexField(UDSTestCase):
+    def test_plain_attr(self) -> None:
+        from uds.core.util.auth import process_regex_field
+
+        self.assertEqual(
+            process_regex_field("group", {"group": ["a", "b"]}),
+            ["a", "b"],
+        )
+
+    def test_plus_concat(self) -> None:
+        from uds.core.util.auth import process_regex_field
+
+        self.assertEqual(
+            process_regex_field("a+b", {"a": ["x"], "b": ["y"]}),
+            ["x", "y"],
+        )
+
+    def test_colon_prefix_rename(self) -> None:
+        from uds.core.util.auth import process_regex_field
+
+        self.assertEqual(
+            process_regex_field(
+                "alumno:alumno\npas:pas\npdi:pdi",
+                {"alumno": ["S"], "pas": ["S"], "pdi": ["N"]},
+            ),
+            ["alumnoS", "pasS", "pdiN"],
+        )
+
+    def test_colon_self_rename(self) -> None:
+        from uds.core.util.auth import process_regex_field
+
+        self.assertEqual(
+            process_regex_field("grupo2:grupo2", {"grupo2": ["foo"]}),
+            ["grupo2foo"],
+        )
+
+    def test_double_star_prefix(self) -> None:
+        from uds.core.util.auth import process_regex_field
+
+        self.assertEqual(
+            process_regex_field("val**pre", {"val": ["S"]}),
+            ["preS"],
+        )
+
+    def test_regex_with_groups(self) -> None:
+        from uds.core.util.auth import process_regex_field
+
+        self.assertEqual(
+            process_regex_field("dn=ou=([^,]+)", {"dn": ["ou=staff,dc=uca"]}),
+            ["staff"],
+        )
+
+    def test_get_attributes_regex_field_colon(self) -> None:
+        from uds.core.util.auth import get_attributes_regex_field
+
+        self.assertEqual(get_attributes_regex_field("alumno:alumno\npas:pas"), {"alumno", "pas"})