Description

WWBN AVideo has Stored XSS via Unanchored Duration Regex in Video Encoder Receiver

Summary

The isValidDuration() regex at objects/video.php:918 uses /^[0-9]{1,2}:[0-9]{1,2}:[0-9]{1,2}/ without a $ end anchor, allowing arbitrary HTML/JavaScript to be appended after a valid duration prefix. The crafted duration is stored in the database and rendered without HTML escaping via echo Video::getCleanDuration() on trending pages, playlist pages, and video gallery thumbnails, resulting in stored cross-site scripting.

Details

Input entry point: objects/aVideoEncoderReceiveImage.json.php:208

// Line 203-211
if (!empty($_REQUEST['duration'])) {
    $video->setDuration($_REQUEST['duration']);
}

Insufficient validation: objects/video.php:918

static function isValidDuration($duration) {
    // ...
    return preg_match('/^[0-9]{1,2}:[0-9]{1,2}:[0-9]{1,2}/', $duration);
    //     Missing $ anchor here -----------------------------------^
}

The regex matches 00:00:01 at the start of the string but ignores everything after it. A payload like 00:00:01</time><img src=x onerror=alert(1)><time> passes validation.

No sanitization in output function: objects/video.php:3463-3480

public static function getCleanDuration($duration = "") {
    $durationParts = explode(".", $duration);
    $duration = $durationParts[0];
    $durationParts = explode(':', $duration);
    if (count($durationParts) == 1) {
        return '0:00:' . static::addZero($durationParts[0]);
    } elseif (count($durationParts) == 2) {
        return '0:' . static::addZero($durationParts[0]) . ':' . static::addZero($durationParts[1]);...
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With the payload 00:00:01</time><img src=x onerror=alert(1)><time>, exploding by : yields 3+ parts, so the full unsanitized string is returned.

Unescaped output sinks:

view/trending.php:72:

<time class="duration"><?php echo Video::getCleanDuration($value['duration']); ?></time>

view/include/playlist.php:159:

<time class="duration"><?php echo Video::getCleanDuration(@$value['duration']); ?></time>

objects/video.php:7200 (gallery thumbnail generation):

$img .= "<time class=\"duration\"...>" . $duration . "</time>";

No Content-Security-Policy headers are set. The application uses raw PHP templates with no auto-escaping framework.

PoC

Authenticate as a user with upload permission and obtain a video_id_hash for a video (visible in encoder API responses or via the upload flow).

Send the malicious duration:

curl -X POST "https://target/objects/aVideoEncoderReceiveImage.json.php" \
  -d "videos_id=VIDEO_ID" \
  -d "video_id_hash=HASH" \
  -d 'duration=00:00:01</time><img src=x onerror=alert(document.cookie)><time>'

The isValidDuration() regex matches the 00:00:01 prefix and allows the full string to be stored.

Visit the trending page (/view/trending.php) or any playlist containing the poisoned video. The injected HTML breaks out of the <time> tag and the onerror handler executes JavaScript in the victim's browser context.

Impact

Session hijacking: Attacker can steal session cookies of any user (including administrators) who views a page listing the poisoned video (trending, playlists, search results, channel pages).

Account takeover: Stolen admin session cookies grant full platform control.

Phishing: Attacker can inject fake login forms or redirect users to malicious sites.

Worm potential: Since the XSS fires on commonly-visited listing pages (trending), it can propagate without targeted delivery — any visitor is a victim.

The attack requires only upload-level permissions (low privilege) and impacts all users who view any page rendering the poisoned video's duration (high blast radius).

Recommended Fix

Fix 1 — Anchor the regex (objects/video.php:918):

- return preg_match('/^[0-9]{1,2}:[0-9]{1,2}:[0-9]{1,2}/', $duration);
+ return preg_match('/^[0-9]{1,2}:[0-9]{1,2}:[0-9]{1,2}(\.[0-9]+)?$/', $duration);

Fix 2 — HTML-escape all duration output (defense in depth):

In view/trending.php:72:

- <time class="duration"><?php echo Video::getCleanDuration($value['duration']); ?></time>
+ <time class="duration"><?php echo htmlspecialchars(Video::getCleanDuration($value['duration']), ENT_QUOTES, 'UTF-8'); ?></time>

In view/include/playlist.php:159:

- <time class="duration"><?php echo Video::getCleanDuration(@$value['duration']); ?></time>
+ <time class="duration"><?php echo htmlspecialchars(Video::getCleanDuration(@$value['duration']), ENT_QUOTES, 'UTF-8'); ?></time>

In objects/video.php:7200:

- $img .= "<time class=\"duration\"...>" . $duration . "</time>";
+ $img .= "<time class=\"duration\"...>" . htmlspecialchars($duration, ENT_QUOTES, 'UTF-8') . "</time>";

Both fixes should be applied: the regex fix prevents storage of invalid data, and the output escaping provides defense in depth against any other code path that might store unvalidated durations.

Mitigation

Aliases

References