Mailing List Archive

Netscape Communicator META Refresh Denial of Service
The "META" tag can be used to specify several things, including
document properties, and HTTP headers. Among the HTTP
header equivalents it can specify is a "Refresh" member.

Refresh has this syntax:

<meta http-equiv="refresh" content="[delay]; URL=[page]">

delay - A number of seconds to wait for reload. If omitted,
no delay is observed and the page is refreshed immediately.

page - This is the URL to navigate to when the refresh occurs

If a META Refresh navigates to itself with no delay, Netscape
will loop, causing a stupid DoS.

I tested this on Netscape 6.2.1 for Win9x/Me, but other versions
may be vulnerable.

"The reason the mainstream is thought
of as a stream is because it is
so shallow."
- Author Unknown
Re: Netscape Communicator META Refresh Denial of Service [ In reply to ]
> If a META Refresh navigates to itself with no delay, Netscape
> will loop, causing a stupid DoS.

Does it repeat the request for the page (or at least do an if-not-changed
GET, or a HEAD request)? IE is supposed to do this, so I always assumed
other browsers treated 'Refresh' the same way. If so, there would be a
(slight) delay, depending upon the connection, and it would, in theory, be a
useful feature.

- lazde