FreeBSD : varnish -- DoS vulnerability in Varnish HTTP cache (d9dbe6e8-84da-11e3-98bd-080027f2d077)

This script is Copyright (C) 2014 Tenable Network Security, Inc.


Synopsis :

The remote FreeBSD host is missing a security-related update.

Description :

Varnish Cache Project reports :

If Varnish receives a certain illegal request, and the subroutine
'vcl_error{}' restarts the request, the varnishd worker process will
crash with an assert.

The varnishd management process will restart the worker process, but
there will be a brief interruption of service and the cache will be
emptied, causing more traffic to go to the backend.

We are releasing this advisory because restarting from vcl_error{} is
both fairly common and documented.

This is purely a denial of service vulnerability, there is no risk of
privilege escalation.

Workaround

Insert this at the top of your VCL file :

sub vcl_error { if (obj.status == 400 || obj.status == 413) {
return(deliver); } }

Or add this test at the top of your existing vcl_error{}.

See also :

http://www.nessus.org/u?ac6e5049
http://www.nessus.org/u?299731c9

Solution :

Update the affected package.

Risk factor :

Medium / CVSS Base Score : 5.0
(CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P)

Family: FreeBSD Local Security Checks

Nessus Plugin ID: 72128 ()

Bugtraq ID:

CVE ID: CVE-2013-4484

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