GHSA-5hgj-7gm9-cff5 AVideo: Unauthenticated Arbitrary Email Sending via sendEmail.json.php Enables Phishing from the Site’s Legitimate From Address
Summary`objects/sendEmail.json.php` exposes two branches depending on whether `contactForm=1` is submitted. When the parameter is omitted, the endpoint sets `$sendTo` to an attacker-supplied email and, for unauthenticated callers, uses the site's own contact email as the message `From:`/`Reply-To:`. The endpoint is explicitly allow-listed as a "public write action" in `objects/functionsSecurity.php` (line 885), so it requires no authentication or CSRF token. An unauthenticated attacker (solving a captcha) can force the site's own SMTP infrastructure to send attacker-composed emails to arbitrary recipients with the site's legitimate sender address, passing SPF/DKIM/DMARC for the site's domain — ideal for targeted phishing and brand impersonation.Details**Vulnerable code (`objects/sendEmail.json.php`):****`User::getEmail_()` (`objects/user.php:345-352`):** returns `''` when the caller is not logged in, driving the fallback to `$config->getContactEmail()`.**Endpoint is publicly callable.** `objects/functionsSecurity.php:879-918` lists `sendEmail.json.php` in the built-in "public write actions" CSRF/same-domain bypass:**Why existing defenses don't mitigate the abuse:****Captcha** (`Captcha::validation`): costs one solve per email. Manual solves remain viable for targeted phishing, and a separate captcha-bypass primitive in this codebase (tracked separately) automates abuse.**`FILTER_VALIDATE_EMAIL`** (line 43): validates `$sendTo` format, preventing CRLF/header injection, but does not verify that the sender is authorized to send to that address.**`htmlspecialchars` on `$safeEmail`/`$safeComment`/`$safeFirstName`**: blocks HTML injection in the rendered message but does not prevent phishing content — attacker fully controls the visible text (URL, instructions) and the perceived sender.**No rate limiting, no auth check, no association between the caller and the recipient address.****Flow summary for the abuse case (unauthenticated, no `contactForm`):**`User::getEmail_()` → `''`, so `$replyTo` = site's contact email (line 32)`$sendTo` = attacker's chosen recipient (line 35)`contactForm` branch skipped (line 38)Site's SMTP sends `From: <site contact>` to `<victim>` with attacker's subject/body (lines 44-51)Because the message is genuinely relayed by the site's mail infrastructure, SPF/DKIM/DMARC for the site's domain pass, making the phishing message indistinguishable from legitimate site mail.PoCEndpoint: `POST /objects/sendEmail.json.php` (also reachable via `POST /sendEmail` per `.htaccess:201`).Expected server response:Delivered headers at `victim@target.com`:Contrast with the intended `contactForm=1` flow (correctly routes to the site owner):Omitting `contactForm` inverts the routing and turns the endpoint into an unauthenticated sender-for-hire using the site's own From: identity.Impact**Phishing with the site's real sender identity.** Mail originates from the site's SMTP, so SPF/DKIM/DMARC pass; the message is indistinguishable from legitimate site communications and bypasses inbox anti-phishing heuristics.**Brand impersonation / account-takeover chains.** Attacker-controlled subject (`first_name`) and body (`comment`) support credential-harvesting pages that appear to come from the site operator.**Mail-reputation damage.** Repeated abuse can blacklist the site's sending IP/domain, degrading legitimate mail deliverability.**Works against any AVideo instance with SMTP configured** — a default deployment after the admin configures SMTP for standard notifications. No privileged position, credentials, or non-default flags required.Recommended FixCollapse the endpoint to contact-owner-only behavior and require either authentication or `contactForm=1`. Minimal patch:Additional hardening:Always use a dedicated `no-reply@` address in `setFrom()`; put the caller's address only in `Reply-To`. Never reuse `$config->getContactEmail()` as the From for user-initiated messages.For the logged-in "share" flow, verify the caller's email has been confirmed, and rate-limit by user id and by IP.Drop the non-`contactForm` branch entirely if no legitimate unauthenticated UI caller remains.Add a visible "user-submitted message via our site" banner to the email body so recipients can distinguish these from first-party communications.
CVSS v3.1 score: 5.3