diff --git a/x-pack/plugin/eql/qa/common/src/main/java/org/elasticsearch/test/eql/EqlRestValidationTestCase.java b/x-pack/plugin/eql/qa/common/src/main/java/org/elasticsearch/test/eql/EqlRestValidationTestCase.java
index a011231729f37..207cc23f0f9bd 100644
--- a/x-pack/plugin/eql/qa/common/src/main/java/org/elasticsearch/test/eql/EqlRestValidationTestCase.java
+++ b/x-pack/plugin/eql/qa/common/src/main/java/org/elasticsearch/test/eql/EqlRestValidationTestCase.java
@@ -52,13 +52,59 @@ public void prepareIndices() throws IOException {
         assertOK(provisioningAdminClient().performRequest(new Request("POST", "/" + indexName + "/_refresh")));
     }
 
-    protected abstract String getInexistentIndexErrorMessage();
+    protected abstract boolean isSecurityEnabled();
+
+    protected String getInexistentIndexErrorMessage() {
+        if (isSecurityEnabled()) {
+            return "\"root_cause\":[{\"type\":\"verification_exception\",\"reason\":\"Found 1 problem\\nline -1:-1: Unknown index ";
+        } else {
+            return "\"root_cause\":[{\"type\":\"verification_exception\",\"reason\":\"Found 1 problem\\nline -1:-1: Unknown index ";
+        }
+    }
 
     protected String getInexistentWildcardErrorMessage() {
-        return getInexistentIndexErrorMessage();
+        if (isSecurityEnabled()) {
+            return """
+                "root_cause":[{"type":"verification_exception","reason":"Found 1 problem\\nline -1:-1: Unknown index [*,-*]"}],\
+                "type":"index_not_found_exception","reason":"no such index\s""";
+        } else {
+            return getInexistentIndexErrorMessage();
+        }
     }
 
-    protected abstract void assertErrorMessageWhenAllowNoIndicesIsFalse(String reqParameter) throws IOException;
+    protected void assertErrorMessageWhenAllowNoIndicesIsFalse(String reqParameter) throws IOException {
+        if (isSecurityEnabled()) {
+            assertErrorMessage("inexistent1*", reqParameter, """
+                "root_cause":[{"type":"index_not_found_exception","reason":"no such index [inexistent1*]\"""");
+            assertErrorMessage("inexistent1*,inexistent2*", reqParameter, """
+                "root_cause":[{"type":"index_not_found_exception","reason":"no such index [inexistent1*]\"""");
+            assertErrorMessage("test_eql,inexistent*", reqParameter, """
+                "root_cause":[{"type":"index_not_found_exception","reason":"no such index [inexistent*]\"""");
+            // TODO: revisit the next two tests when https://github.com/elastic/elasticsearch/issues/64190 is closed
+            assertErrorMessage("inexistent", reqParameter, """
+                "root_cause":[{"type":"index_not_found_exception","reason":"no such index [inexistent]\"""");
+            assertErrorMessage("inexistent1,inexistent2", reqParameter, """
+                "root_cause":[{"type":"index_not_found_exception","reason":"no such index [null]\"""");
+        } else {
+            assertErrorMessage("inexistent1*", reqParameter, """
+                "root_cause":[{"type":"index_not_found_exception","reason":"no such index [inexistent1*]\"""");
+            assertErrorMessage("inexistent1*,inexistent2*", reqParameter, """
+                "root_cause":[{"type":"index_not_found_exception","reason":"no such index [inexistent1*]\"""");
+            assertErrorMessage("test_eql,inexistent*", reqParameter, """
+                "root_cause":[{"type":"index_not_found_exception","reason":"no such index [inexistent*]\"""");
+            assertErrorMessage("inexistent", reqParameter, """
+                "root_cause":[{"type":"index_not_found_exception","reason":"no such index [inexistent]\"""");
+            // TODO: revisit after
+            // https://github.com/elastic/elasticsearch/issues/64197
+            // is closed
+            assertErrorMessage(
+                "inexistent1,inexistent2",
+                reqParameter,
+                "\"root_cause\":[{\"type\":\"index_not_found_exception\",\"reason\":\"no such index [null]\","
+                    + "\"resource.type\":\"index_expression\",\"resource.id\":[\"inexistent1\",\"inexistent2\"]}]"
+            );
+        }
+    }
 
     public void testDefaultIndicesOptions() throws IOException {
         assertErrorMessages(inexistentIndexNameWithWildcard, EMPTY, getInexistentWildcardErrorMessage());
diff --git a/x-pack/plugin/eql/qa/common/src/main/java/org/elasticsearch/test/eql/RemoteClusterAwareEqlRestTestCase.java b/x-pack/plugin/eql/qa/common/src/main/java/org/elasticsearch/test/eql/RemoteClusterAwareEqlRestTestCase.java
index 739f3fc83cd1e..04182bbeb3d7f 100644
--- a/x-pack/plugin/eql/qa/common/src/main/java/org/elasticsearch/test/eql/RemoteClusterAwareEqlRestTestCase.java
+++ b/x-pack/plugin/eql/qa/common/src/main/java/org/elasticsearch/test/eql/RemoteClusterAwareEqlRestTestCase.java
@@ -119,7 +119,7 @@ protected static void deleteIndexWithProvisioningClient(String name) throws IOEx
 
     @Override
     protected Settings restClientSettings() {
-        return secureRemoteClientSettings();
+        return Settings.builder().put(super.restClientSettings()).put(secureRemoteClientSettings()).build();
     }
 
     protected static Settings secureRemoteClientSettings() {
diff --git a/x-pack/plugin/eql/qa/common/src/main/java/org/elasticsearch/test/eql/stats/EqlUsageRestTestCase.java b/x-pack/plugin/eql/qa/common/src/main/java/org/elasticsearch/test/eql/stats/EqlUsageRestTestCase.java
index 7c1804f2a5a32..b7a9bb2919a71 100644
--- a/x-pack/plugin/eql/qa/common/src/main/java/org/elasticsearch/test/eql/stats/EqlUsageRestTestCase.java
+++ b/x-pack/plugin/eql/qa/common/src/main/java/org/elasticsearch/test/eql/stats/EqlUsageRestTestCase.java
@@ -9,9 +9,6 @@
 
 import org.elasticsearch.client.Request;
 import org.elasticsearch.client.RestHighLevelClient;
-import org.elasticsearch.common.settings.SecureString;
-import org.elasticsearch.common.settings.Settings;
-import org.elasticsearch.common.util.concurrent.ThreadContext;
 import org.elasticsearch.common.xcontent.XContentHelper;
 import org.elasticsearch.test.eql.DataLoader;
 import org.elasticsearch.test.rest.ESRestTestCase;
@@ -390,9 +387,4 @@ private RestHighLevelClient highLevelClient() {
         return highLevelClient;
     }
 
-    @Override
-    protected Settings restClientSettings() {
-        String token = basicAuthHeaderValue("admin", new SecureString("admin-password".toCharArray()));
-        return Settings.builder().put(ThreadContext.PREFIX + ".Authorization", token).build();
-    }
 }
diff --git a/x-pack/plugin/eql/qa/multi-cluster-with-security/src/javaRestTest/java/org/elasticsearch/xpack/eql/EqlRestValidationIT.java b/x-pack/plugin/eql/qa/multi-cluster-with-security/src/javaRestTest/java/org/elasticsearch/xpack/eql/EqlRestValidationIT.java
index a9f1d22ce0969..fd52776f65f00 100644
--- a/x-pack/plugin/eql/qa/multi-cluster-with-security/src/javaRestTest/java/org/elasticsearch/xpack/eql/EqlRestValidationIT.java
+++ b/x-pack/plugin/eql/qa/multi-cluster-with-security/src/javaRestTest/java/org/elasticsearch/xpack/eql/EqlRestValidationIT.java
@@ -20,6 +20,11 @@ protected String getInexistentIndexErrorMessage() {
         return "\"root_cause\":[{\"type\":\"index_not_found_exception\",\"reason\":\"no such index ";
     }
 
+    @Override
+    protected boolean isSecurityEnabled() {
+        return true;
+    }
+
     protected void assertErrorMessageWhenAllowNoIndicesIsFalse(String reqParameter) throws IOException {
         assertErrorMessage("inexistent1*", reqParameter, getInexistentIndexErrorMessage() + "[" + indexPattern("inexistent1*") + "]\"");
         assertErrorMessage(
diff --git a/x-pack/plugin/eql/qa/rest/src/javaRestTest/java/org/elasticsearch/xpack/eql/EqlRestIT.java b/x-pack/plugin/eql/qa/rest/src/javaRestTest/java/org/elasticsearch/xpack/eql/EqlRestIT.java
index ed019f5cb1317..0343f41dd4147 100644
--- a/x-pack/plugin/eql/qa/rest/src/javaRestTest/java/org/elasticsearch/xpack/eql/EqlRestIT.java
+++ b/x-pack/plugin/eql/qa/rest/src/javaRestTest/java/org/elasticsearch/xpack/eql/EqlRestIT.java
@@ -7,9 +7,6 @@
 
 package org.elasticsearch.xpack.eql;
 
-import org.elasticsearch.common.settings.SecureString;
-import org.elasticsearch.common.settings.Settings;
-import org.elasticsearch.common.util.concurrent.ThreadContext;
 import org.elasticsearch.test.cluster.ElasticsearchCluster;
 import org.elasticsearch.test.eql.EqlRestTestCase;
 import org.junit.ClassRule;
@@ -24,9 +21,4 @@ protected String getTestRestCluster() {
         return cluster.getHttpAddresses();
     }
 
-    @Override
-    protected Settings restClientSettings() {
-        String token = basicAuthHeaderValue("admin", new SecureString("admin-password".toCharArray()));
-        return Settings.builder().put(ThreadContext.PREFIX + ".Authorization", token).build();
-    }
 }
diff --git a/x-pack/plugin/eql/qa/rest/src/javaRestTest/java/org/elasticsearch/xpack/eql/EqlRestValidationIT.java b/x-pack/plugin/eql/qa/rest/src/javaRestTest/java/org/elasticsearch/xpack/eql/EqlRestValidationIT.java
index 46fd25d2f163c..009842b2bbe79 100644
--- a/x-pack/plugin/eql/qa/rest/src/javaRestTest/java/org/elasticsearch/xpack/eql/EqlRestValidationIT.java
+++ b/x-pack/plugin/eql/qa/rest/src/javaRestTest/java/org/elasticsearch/xpack/eql/EqlRestValidationIT.java
@@ -11,8 +11,6 @@
 import org.elasticsearch.test.eql.EqlRestValidationTestCase;
 import org.junit.ClassRule;
 
-import java.io.IOException;
-
 public class EqlRestValidationIT extends EqlRestValidationTestCase {
 
     @ClassRule
@@ -24,27 +22,7 @@ protected String getTestRestCluster() {
     }
 
     @Override
-    protected String getInexistentIndexErrorMessage() {
-        return "\"root_cause\":[{\"type\":\"verification_exception\",\"reason\":\"Found 1 problem\\nline -1:-1: Unknown index ";
-    }
-
-    protected void assertErrorMessageWhenAllowNoIndicesIsFalse(String reqParameter) throws IOException {
-        assertErrorMessage("inexistent1*", reqParameter, """
-            "root_cause":[{"type":"index_not_found_exception","reason":"no such index [inexistent1*]\"""");
-        assertErrorMessage("inexistent1*,inexistent2*", reqParameter, """
-            "root_cause":[{"type":"index_not_found_exception","reason":"no such index [inexistent1*]\"""");
-        assertErrorMessage("test_eql,inexistent*", reqParameter, """
-            "root_cause":[{"type":"index_not_found_exception","reason":"no such index [inexistent*]\"""");
-        assertErrorMessage("inexistent", reqParameter, """
-            "root_cause":[{"type":"index_not_found_exception","reason":"no such index [inexistent]\"""");
-        // TODO: revisit after
-        // https://github.com/elastic/elasticsearch/issues/64197
-        // is closed
-        assertErrorMessage(
-            "inexistent1,inexistent2",
-            reqParameter,
-            "\"root_cause\":[{\"type\":\"index_not_found_exception\",\"reason\":\"no such index [null]\","
-                + "\"resource.type\":\"index_expression\",\"resource.id\":[\"inexistent1\",\"inexistent2\"]}]"
-        );
+    protected boolean isSecurityEnabled() {
+        return cluster.isSecurityEnabled();
     }
 }
diff --git a/x-pack/plugin/eql/qa/security/src/javaRestTest/java/org/elasticsearch/xpack/eql/EqlRestValidationIT.java b/x-pack/plugin/eql/qa/security/src/javaRestTest/java/org/elasticsearch/xpack/eql/EqlRestValidationIT.java
index 8887536379c3b..0689f9913ddb2 100644
--- a/x-pack/plugin/eql/qa/security/src/javaRestTest/java/org/elasticsearch/xpack/eql/EqlRestValidationIT.java
+++ b/x-pack/plugin/eql/qa/security/src/javaRestTest/java/org/elasticsearch/xpack/eql/EqlRestValidationIT.java
@@ -12,8 +12,6 @@
 import org.elasticsearch.test.eql.EqlRestValidationTestCase;
 import org.junit.ClassRule;
 
-import java.io.IOException;
-
 import static org.elasticsearch.xpack.eql.SecurityUtils.secureClientSettings;
 
 public class EqlRestValidationIT extends EqlRestValidationTestCase {
@@ -31,30 +29,7 @@ protected Settings restClientSettings() {
     }
 
     @Override
-    protected String getInexistentIndexErrorMessage() {
-        return "\"root_cause\":[{\"type\":\"verification_exception\",\"reason\":\"Found 1 problem\\nline -1:-1: Unknown index ";
-    }
-
-    @Override
-    protected String getInexistentWildcardErrorMessage() {
-        return """
-            "root_cause":[{"type":"verification_exception","reason":"Found 1 problem\\nline -1:-1: Unknown index [*,-*]"}],\
-            "type":"index_not_found_exception","reason":"no such index\s""";
+    protected boolean isSecurityEnabled() {
+        return true;
     }
-
-    @Override
-    protected void assertErrorMessageWhenAllowNoIndicesIsFalse(String reqParameter) throws IOException {
-        assertErrorMessage("inexistent1*", reqParameter, """
-            "root_cause":[{"type":"index_not_found_exception","reason":"no such index [inexistent1*]\"""");
-        assertErrorMessage("inexistent1*,inexistent2*", reqParameter, """
-            "root_cause":[{"type":"index_not_found_exception","reason":"no such index [inexistent1*]\"""");
-        assertErrorMessage("test_eql,inexistent*", reqParameter, """
-            "root_cause":[{"type":"index_not_found_exception","reason":"no such index [inexistent*]\"""");
-        // TODO: revisit the next two tests when https://github.com/elastic/elasticsearch/issues/64190 is closed
-        assertErrorMessage("inexistent", reqParameter, """
-            "root_cause":[{"type":"index_not_found_exception","reason":"no such index [inexistent]\"""");
-        assertErrorMessage("inexistent1,inexistent2", reqParameter, """
-            "root_cause":[{"type":"index_not_found_exception","reason":"no such index [null]\"""");
-    }
-
 }