CVE-2021-21396 (published 2021-03-26T22:15Z)

wire-server is an open-source back end for Wire, a secure collaboration platform. In wire-server from version 2021-02-16 and before version 2021-03-02, the client metadata of all users was exposed in the `GET /users/list-clients` endpoint. The endpoint could be used by any logged in user who could request client details of any other user (no connection required) as far as they can find their User ID. The exposed metadata included id, class, type, location, time, and cookie. A user on a Wire backend could use this endpoint to find registration time and location for each device for a given list of users. As a workaround, remove `/list-clients` from nginx config. This has been fixed in version 2021-03-02.

Severity: MEDIUM
CVSS v2 base score: 4.0 (AV:N/AC:L/Au:S/C:P/I:N/A:N)
CVSS v3 base score: 6.5, MEDIUM (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/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/wireapp/wire-server
commit_details: repo_url: https://github.com/wireapp/wire-server
author: Akshay Mankar
author_date: 2021-03-02 12:14:30+01:00
msg: Return PubClient instead of Client from /users/list-clients (#1391)
repository: repo_url: https://github.com/wireapp/wire-server
repo_name: wireapp/wire-server
description: 🇪🇺 Wire back-end services
repo_language: Haskell
owner: wireapp
file_changes: filename: Client.hs
change_type: ModificationType.MODIFY
diff: @@ -312,8 +312,9 @@ data PubClient = PubClient
   { pubClientId :: ClientId,
     pubClientClass :: Maybe ClientClass
   }
-  deriving stock (Eq, Show, Generic)
+  deriving stock (Eq, Show, Generic, Ord)
   deriving (Arbitrary) via (GenericUniform PubClient)
+  deriving (ToSchema) via (CustomSwagger '[FieldLabelModifier (StripPrefix "pubClient", LowerCase)] PubClient)
 
 modelPubClient :: Doc.Model
 modelPubClient = Doc.defineModel "PubClient" $ do

programming_language: Haskell
filename: UserMap.hs
change_type: ModificationType.MODIFY
diff: @@ -15,11 +15,10 @@ import Data.Typeable (typeRep)
 import Imports
 import Test.QuickCheck (Arbitrary (..))
 import Wire.API.Arbitrary (generateExample, mapOf')
-import Wire.API.User.Client (Client)
 
 newtype UserMap a = UserMap {userMap :: Map UserId a}
   deriving stock (Eq, Show)
-  deriving newtype (Semigroup, Monoid, ToJSON, FromJSON)
+  deriving newtype (Semigroup, Monoid, ToJSON, FromJSON, Functor)
 
 instance Arbitrary a => Arbitrary (UserMap a) where
   arbitrary = UserMap <$> mapOf' arbitrary arbitrary
@@ -30,17 +29,22 @@ newtype QualifiedUserMap a = QualifiedUserMap
   deriving stock (Eq, Show)
   deriving newtype (Semigroup, Monoid, ToJSON, FromJSON)
 
+instance Functor QualifiedUserMap where
+  fmap f (QualifiedUserMap qMap) =
+    QualifiedUserMap $ f <$$> qMap
+
 instance Arbitrary a => Arbitrary (QualifiedUserMap a) where
   arbitrary = QualifiedUserMap <$> mapOf' arbitrary arbitrary
 
-instance ToSchema (UserMap (Set Client)) where
+instance (Typeable a, ToSchema a, ToJSON a, Arbitrary a) => ToSchema (UserMap (Set a)) where
   declareNamedSchema _ = do
-    mapSch <- declareSchema (Proxy @(Map UserId (Set Client)))
+    mapSch <- declareSchema (Proxy @(Map UserId (Set a)))
+    let valueTypeName = Text.pack $ show $ typeRep $ Proxy @a
     return $
-      NamedSchema (Just "UserMap (Set Client)") $
+      NamedSchema (Just $ "UserMap (Set " <> valueTypeName <> ")") $
         mapSch
-          & description ?~ "Map of UserId to (Set Client)"
-          & example ?~ toJSON (Map.singleton (generateExample @UserId) (Set.singleton (generateExample @Client)))
+          & description ?~ "Map of UserId to (Set " <> valueTypeName <> ")"
+          & example ?~ toJSON (Map.singleton (generateExample @UserId) (Set.singleton (generateExample @a)))
 
 instance (Typeable a, ToSchema (UserMap a)) => ToSchema (QualifiedUserMap a) where
   declareNamedSchema _ = do

programming_language: Haskell
filename: Swagger.hs
change_type: ModificationType.MODIFY
diff: @@ -37,10 +37,12 @@ tests =
       testToJSON @User.SelfProfile,
       testToJSON @Handle.UserHandleInfo,
       testToJSON @Client.Client,
-      testToJSON @(Client.UserClientMap (Maybe Prekey.Prekey)),
-      testToJSON @Client.UserClients,
+      testToJSON @Client.PubClient,
       testToJSON @(UserMap.UserMap (Set Client.Client)),
+      testToJSON @(UserMap.UserMap (Set Client.PubClient)),
       testToJSON @(UserMap.QualifiedUserMap (Set Client.Client)),
+      testToJSON @(Client.UserClientMap (Maybe Prekey.Prekey)),
+      testToJSON @Client.UserClients,
       testToJSON @Prekey.Prekey,
       testToJSON @Prekey.PrekeyBundle,
       testToJSON @Prekey.ClientPrekey,

programming_language: Haskell
filename: Public.hs
change_type: ModificationType.MODIFY
diff: @@ -71,6 +71,7 @@ import qualified Data.Map.Strict as Map
 import Data.Misc (IpAddr (..))
 import Data.Qualified (Qualified (..), partitionRemoteOrLocalIds)
 import Data.Range
+import qualified Data.Set as Set
 import Data.Swagger
   ( ApiKeyLocation (..),
     ApiKeyParams (..),
@@ -306,7 +307,7 @@ type ListClientsBulk =
     :> "users"
     :> "list-clients"
     :> Servant.ReqBody '[Servant.JSON] (Range 1 MaxUsersForListClientsBulk [Qualified UserId])
-    :> Post '[Servant.JSON] (Public.QualifiedUserMap (Set Public.Client))
+    :> Post '[Servant.JSON] (Public.QualifiedUserMap (Set Public.PubClient))
 
 type GetUsersPrekeysClientUnqualified =
   Summary "(deprecated) Get a prekey for a specific client of a user."
@@ -1148,9 +1149,9 @@ getClientH (zusr ::: clt ::: _) =
     Just c -> json c
     Nothing -> setStatus status404 empty
 
-listClientsBulk :: UserId -> Range 1 MaxUsersForListClientsBulk [Qualified UserId] -> Handler (Public.QualifiedUserMap (Set Public.Client))
-listClientsBulk _zusr limitedUids =
-  API.lookupClientsBulk (fromRange limitedUids) !>> clientError
+listClientsBulk :: UserId -> Range 1 MaxUsersForListClientsBulk [Qualified UserId] -> Handler (Public.QualifiedUserMap (Set Public.PubClient))
+listClientsBulk _zusr limitedUids = do
+  Set.map API.pubClient <$$> API.lookupClientsBulk (fromRange limitedUids) !>> clientError
 
 getClient :: UserId -> ClientId -> Handler (Maybe Public.Client)
 getClient zusr clientId = do

programming_language: Haskell
filename: Client.hs
change_type: ModificationType.MODIFY
diff: @@ -178,12 +178,16 @@ testListClientsBulk opts brig = do
 
   let domain = Opt.setFederationDomain $ Opt.optSettings opts
   uid3 <- userId <$> randomUser brig
-  let expectedResponse :: QualifiedUserMap (Set Client) =
+  let mkPubClient cl = PubClient (clientId cl) (clientClass cl)
+  let expectedResponse :: QualifiedUserMap (Set PubClient) =
         QualifiedUserMap $
           Map.singleton
             domain
             ( UserMap $
-                Map.fromList [(uid1, Set.fromList [c11, c12, c13]), (uid2, Set.fromList [c21, c22])]
+                Map.fromList
+                  [ (uid1, Set.fromList $ mkPubClient <$> [c11, c12, c13]),
+                    (uid2, Set.fromList $ mkPubClient <$> [c21, c22])
+                  ]
             )
   post
     ( brig

programming_language: Haskell