CVE-2022-21677 (published 2022-01-14T17:15Z)

Discourse is an open source discussion platform. Discourse groups can be configured with varying visibility levels for the group as well as the group members. By default, a newly created group has its visibility set to public and the group's members visibility set to public as well. However, a group's visibility and the group's members visibility can be configured such that it is restricted to logged on users, members of the group or staff users. A vulnerability has been discovered in versions prior to 2.7.13 and 2.8.0.beta11 where the group advanced search option does not respect the group's visibility and members visibility level. As such, a group with restricted visibility or members visibility can be revealed through search with the right search option. This issue is patched in `stable` version 2.7.13, `beta` version 2.8.0.beta11, and `tests-passed` version 2.8.0.beta11 versions of Discourse. There are no workarounds aside from upgrading.

Severity: MEDIUM
CVSS v2 base score: 5.0 (AV:N/AC:L/Au:N/C:P/I:N/A:N)
CVSS v3 base score: 5.3, MEDIUM (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N)

Weakness information:
cwe_id: CWE-200
cwe_name: Exposure of Sensitive Information to an Unauthorized Actor
description: The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
extended_description: 
	   There are many different kinds of mistakes that introduce information exposures. The severity of the error can range widely, depending on the context in which the product operates, the type of sensitive information that is revealed, and the benefits it may provide to an attacker.  Some kinds of sensitive information include:
       
         private, personal information, such as personal messages, financial data, health records, geographic location, or contact details
         system status and environment, such as the operating system and installed packages
		 business secrets and intellectual property
		 network status and configuration
		 the product's own code or internal state
         metadata, e.g. logging of connections or message headers
		 indirect information, such as a discrepancy between two internal operations that can be observed by an outsider
       
	    Information might be sensitive to different parties, each of which may have their own expectations for whether the information should be protected.  These parties include:
               
                  the product's own users
                  people or organizations whose information is created or used by the product, even if they are not direct product users
		  the product's administrators, including the admins of the system(s) and/or networks on which the product operates
                  the developer
               
	    Information exposures can occur in different ways:
               
                  the code explicitly inserts sensitive information into resources or messages that are intentionally made accessible to unauthorized actors, but should not contain the information - i.e., the information should have been "scrubbed" or "sanitized"
                  a different weakness or mistake indirectly inserts the sensitive information into resources, such as a web script error revealing the full system path of the program.
                  the code manages resources that intentionally contain sensitive information, but the resources are unintentionally made accessible to unauthorized actors. In this case, the information exposure is resultant - i.e., a different weakness enabled the access to the information in the first place.
               
	    It is common practice to describe any loss of confidentiality as an "information exposure," but this can lead to overuse of CWE-200 in CWE mapping. From the CWE perspective, loss of confidentiality is a technical impact that can arise from dozens of different weaknesses, such as insecure file permissions or out-of-bounds read.  CWE-200 and its lower-level descendants are intended to cover the mistakes that occur in behaviors that explicitly manage, store, transfer, or cleanse sensitive information.
         
         

Fix information:
repo_url: https://github.com/discourse/discourse
commit_details: repo_url: https://github.com/discourse/discourse
author: Alan Guo Xiang Tan
author_date: 2022-01-10 11:28:20+08:00
msg: SECURITY: Advanced group search did not respect visiblity of groups.
repository: repo_url: https://github.com/discourse/discourse
repo_name: discourse/discourse
description: A platform for community discussion. Free, open, simple.
repo_language: Ruby
owner: discourse
file_changes: filename: search.rb
change_type: ModificationType.MODIFY
diff: @@ -583,7 +583,11 @@ class Search
   end
 
   advanced_filter(/^group:(.+)$/i) do |posts, match|
-    group_id = Group.where('name ilike ? OR (id = ? AND id > 0)', match, match.to_i).pluck_first(:id)
+    group_id = Group
+      .visible_groups(@guardian.user)
+      .members_visible_groups(@guardian.user)
+      .where('name ilike ? OR (id = ? AND id > 0)', match, match.to_i).pluck_first(:id)
+
     if group_id
       posts.where("posts.user_id IN (select gu.user_id from group_users gu where gu.group_id = ?)", group_id)
     else

programming_language: Ruby
filename: search_spec.rb
change_type: ModificationType.MODIFY
diff: @@ -1248,15 +1248,55 @@ describe Search do
       expect(Search.execute("@#{post_1.user.username}").posts).to contain_exactly(post_1)
     end
 
-    it 'supports group' do
-      topic = Fabricate(:topic, created_at: 3.months.ago)
-      post = Fabricate(:post, raw: 'hi this is a test 123 123', topic: topic)
+    context "searching for posts made by users of a group" do
+      fab!(:topic) { Fabricate(:topic, created_at: 3.months.ago) }
+      fab!(:user) { Fabricate(:user) }
+      fab!(:user_2) { Fabricate(:user) }
+      fab!(:user_3) { Fabricate(:user) }
+      fab!(:group) { Fabricate(:group, name: "Like_a_Boss").tap { |g| g.add(user) } }
+      fab!(:group_2) { Fabricate(:group).tap { |g| g.add(user_2) } }
+      let!(:post) { Fabricate(:post, raw: 'hi this is a test 123 123', topic: topic, user: user) }
+      let!(:post_2) { Fabricate(:post, user: user_2) }
+
+      it 'should not return any posts if group does not exist' do
+        group.update!(
+          visibility_level: Group.visibility_levels[:public],
+          members_visibility_level: Group.visibility_levels[:public]
+        )
+
+        expect(Search.execute('group:99999').posts).to eq([])
+      end
+
+      it 'should return the right posts for a public group' do
+        group.update!(
+          visibility_level: Group.visibility_levels[:public],
+          members_visibility_level: Group.visibility_levels[:public]
+        )
 
-      group = Group.create!(name: "Like_a_Boss")
-      GroupUser.create!(user_id: post.user_id, group_id: group.id)
+        expect(Search.execute('group:like_a_boss').posts).to contain_exactly(post)
+        expect(Search.execute("group:#{group.id}").posts).to contain_exactly(post)
+      end
 
-      expect(Search.execute('group:like_a_boss').posts.length).to eq(1)
-      expect(Search.execute('group:"like a brick"').posts.length).to eq(0)
+      it "should return the right posts for a public group with members' visibility restricted to logged on users" do
+        group.update!(
+          visibility_level: Group.visibility_levels[:public],
+          members_visibility_level: Group.visibility_levels[:logged_on_users]
+        )
+
+        expect(Search.execute("group:#{group.id}").posts).to eq([])
+        expect(Search.execute("group:#{group.id}", guardian: Guardian.new(user_3)).posts).to contain_exactly(post)
+      end
+
+      it "should return the right posts for a group with visibility restricted to logged on users with members' visibility restricted to members" do
+        group.update!(
+          visibility_level: Group.visibility_levels[:logged_on_users],
+          members_visibility_level: Group.visibility_levels[:members]
+        )
+
+        expect(Search.execute("group:#{group.id}").posts).to eq([])
+        expect(Search.execute("group:#{group.id}", guardian: Guardian.new(user_3)).posts).to eq([])
+        expect(Search.execute("group:#{group.id}", guardian: Guardian.new(user)).posts).to contain_exactly(post)
+      end
     end
 
     it 'supports badge' do

programming_language: Ruby