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Posted to dev@httpd.apache.org by Eric Covener <co...@gmail.com> on 2011/08/24 15:17:37 UTC

Re: CVE-2011-3192: Range header DoS vulnerability in Apache 1.3 and Apache 2 (DRAFT-3)

> *       Is this the right list (and order) of the mitigations - or should ReWrite be first ?
FWIW I don't like rewrite first because it's so unruly with being
defined once per vhost + main server + RewriteEngine on.

I like RequestHeader simplicity, and could be combined with SetEnvIf
to only zap long malicious looking headers.

Re: VOTES please -- CVE-2011-3192: Range header DoS vulnerability in Apache 1.3 and Apache 2 (Final-6)

Posted by Eric Covener <co...@gmail.com>.
see inline updates

On Wed, Aug 24, 2011 at 10:56 AM, Dirk-Willem van Gulik
<di...@webweaving.org> wrote:
> Various suggest on-list and off-list fixes applied. Thanks all.
>
> A few more +1's would be nice :)
>
> Dw.
>
>
>
>
>
> Title:    CVE-2011-3192: Range header DoS vulnerability Apache HTTPD 1.3/2.x
>          Apache HTTPD Security ADVISORY
>
> Date:     20110824 1600Z
> Product:  Apache HTTPD Web Server
> Versions: Apache 1.3 all versions, Apache 2 all versions
>
> Description:
> ------------
>
> A denial of service vulnerability has been found in the way the multiple overlapping ranges are handled by the Apache HTTPD server:
>
>     http://seclists.org/fulldisclosure/2011/Aug/175
>
> An attack tool is circulating in the wild. Active use of this tools has been observed.
>
> The attack can be done remotely and with a modest number of requests can cause very significant memory and CPU usage on the server.
>
> The default Apache HTTPD installation is vulnerable.
>
> There is currently no patch/new version of Apache HTTPD which fixes this vulnerability. This advisory will be updated when a long term fix is available.
>
> A full fix is expected in the next 48 hours.
>
> Mitigation:
> ------------
>
> However there are several immediate options to mitigate this issue until that time.
>
> 1) Use mod_rewrite to limit the number of ranges:

^ clarify due to directive addition

>
>   Option 1:
>          # drop Range header when more than 5 ranges.
>          # CVE-2011-3192
>          SetEnvIf Range (,.*?){5,} bad-range=1
>          RequestHeader unset Range env=bad-range
>
>          # optional logging.
>          CustomLog logs/range-CVE-2011-3192.log common env=bad-range
>
>   Option 2:
>          # Reject request when more than 5 ranges in the Range: header.
>          # CVE-2011-3192. Must be added to each VirtualHost and once
>          # in the base configuration.

+RewriteEngine on

>          RewriteCond %{HTTP:range} !(^bytes=[^,]+(,[^,]+){0,4}$|^$)
>          RewriteRule .* - [F]
>
>   The number 5 is arbitrary. Several 10's should not be an issue and may be
>   required for sites which for example serve PDFs to very high end eReaders
>   or use things such complex http based video streaming.
>
> 2) Limit the size of the request field to a few hundred bytes. Note that while this
>   keeps the offending Range header short - it may break other headers; such as
>   sizeable cookies or security fields.
>
>          LimitRequestFieldSize 200
>
>   Note that as the attack evolves in the field you are likely to have
>   to further limit this and/or impose other LimitRequestFields limits.
>
>   See: http://httpd.apache.org/docs/2.2/mod/core.html#limitrequestfieldsize
>
> 3) Use mod_headers to completely dis-allow the use of Range headers:
>
>          RequestHeader unset Range
>
>   Note that this may break certain clients - such as those used for
>   e-Readers and progressive/http-streaming video.
>
> 4) Deploy a Range header count module as a temporary stopgap measure:
>
>     http://people.apache.org/~dirkx/mod_rangecnt.c
>
>   Precompiled binaries for some platforms are available at:
>
>        http://people.apache.org/~dirkx/BINARIES.txt
>
> 5) Apply any of the current patches under discussion - such as:
>
>   http://mail-archives.apache.org/mod_mbox/httpd-dev/201108.mbox/%3cCAAPSnn2PO-d-C4nQt_TES2RRWiZr7urefhTKPWBC1b+K1Dqc7g@mail.gmail.com%3e
>
> Actions:
> -----------
> Apache HTTPD users who are concerned about a DoS attack against their server should consider implementing any of the above mitigations immediately.
>
> When using a third party attack tool to verify vulnerability - know that most of the versions in the wild currently check for the presence of mod_deflate; and will (mis)report that your server is not vulnerable if this module is not present. This vulnerability is not dependent on presence or absence of that module.
>
> Planning:
> -------------
> This advisory will be updated when new information, a patch or a new release is available. A patch or new apache release for Apache 2.0 and 2.2 is expected in the next 48 hours. Note that, while popular, Apache 1.3 is deprecated.
>
>



-- 
Eric Covener
covener@gmail.com

Re: VOTES please -- CVE-2011-3192: Range header DoS vulnerability in Apache 1.3 and Apache 2 (Final-6)

Posted by Greg Ames <am...@gmail.com>.
On Wed, Aug 24, 2011 at 10:56 AM, Dirk-Willem van Gulik <
dirkx@webweaving.org> wrote:

+1 with Eric's edits. specifically,

>
> 1) Use mod_rewrite to limit the number of ranges:
>

Option 1 doesn't use mod_rewrite.

  Option 1:
>          # drop Range header when more than 5 ranges.
>          # CVE-2011-3192
>          SetEnvIf Range (,.*?){5,} bad-range=1
>          RequestHeader unset Range env=bad-range
>
>          # optional logging.
>          CustomLog logs/range-CVE-2011-3192.log common env=bad-range
>

Greg

Re: VOTES please -- CVE-2011-3192: Range header DoS vulnerability in Apache 1.3 and Apache 2 (Final-6)

Posted by Jim Jagielski <ji...@jaguNET.com>.
With the current fixes, +1

On Aug 24, 2011, at 10:56 AM, Dirk-Willem van Gulik wrote:

> Various suggest on-list and off-list fixes applied. Thanks all.
> 
> A few more +1's would be nice :)
> 
> Dw.
> 
> 
> 
> 
> 
> Title:    CVE-2011-3192: Range header DoS vulnerability Apache HTTPD 1.3/2.x
>          Apache HTTPD Security ADVISORY
> 
> Date:     20110824 1600Z
> Product:  Apache HTTPD Web Server
> Versions: Apache 1.3 all versions, Apache 2 all versions
> 
> Description:
> ------------
> 
> A denial of service vulnerability has been found in the way the multiple overlapping ranges are handled by the Apache HTTPD server:
> 
>     http://seclists.org/fulldisclosure/2011/Aug/175  
> 
> An attack tool is circulating in the wild. Active use of this tools has been observed.
> 
> The attack can be done remotely and with a modest number of requests can cause very significant memory and CPU usage on the server. 
> 
> The default Apache HTTPD installation is vulnerable.
> 
> There is currently no patch/new version of Apache HTTPD which fixes this vulnerability. This advisory will be updated when a long term fix is available. 
> 
> A full fix is expected in the next 48 hours. 
> 
> Mitigation:
> ------------
> 
> However there are several immediate options to mitigate this issue until that time. 
> 
> 1) Use mod_rewrite to limit the number of ranges:
> 
>   Option 1:
>          # drop Range header when more than 5 ranges.
>          # CVE-2011-3192
>          SetEnvIf Range (,.*?){5,} bad-range=1
>          RequestHeader unset Range env=bad-range
> 
>          # optional logging.
>          CustomLog logs/range-CVE-2011-3192.log common env=bad-range
> 
>   Option 2:
>          # Reject request when more than 5 ranges in the Range: header.
>          # CVE-2011-3192
>          #
>          RewriteCond %{HTTP:range} !(^bytes=[^,]+(,[^,]+){0,4}$|^$)
>          RewriteRule .* - [F]
> 
>   The number 5 is arbitrary. Several 10's should not be an issue and may be
>   required for sites which for example serve PDFs to very high end eReaders
>   or use things such complex http based video streaming.
> 
> 2) Limit the size of the request field to a few hundred bytes. Note that while this
>   keeps the offending Range header short - it may break other headers; such as 
>   sizeable cookies or security fields. 
> 
>          LimitRequestFieldSize 200
> 
>   Note that as the attack evolves in the field you are likely to have
>   to further limit this and/or impose other LimitRequestFields limits.
> 
>   See: http://httpd.apache.org/docs/2.2/mod/core.html#limitrequestfieldsize
> 
> 3) Use mod_headers to completely dis-allow the use of Range headers:
> 
>          RequestHeader unset Range 
> 
>   Note that this may break certain clients - such as those used for
>   e-Readers and progressive/http-streaming video.
> 
> 4) Deploy a Range header count module as a temporary stopgap measure:
> 
>     http://people.apache.org/~dirkx/mod_rangecnt.c
> 
>   Precompiled binaries for some platforms are available at:
> 
> 	http://people.apache.org/~dirkx/BINARIES.txt
> 
> 5) Apply any of the current patches under discussion - such as:
> 
>   http://mail-archives.apache.org/mod_mbox/httpd-dev/201108.mbox/%3cCAAPSnn2PO-d-C4nQt_TES2RRWiZr7urefhTKPWBC1b+K1Dqc7g@mail.gmail.com%3e
> 
> Actions:
> -----------
> Apache HTTPD users who are concerned about a DoS attack against their server should consider implementing any of the above mitigations immediately. 
> 
> When using a third party attack tool to verify vulnerability - know that most of the versions in the wild currently check for the presence of mod_deflate; and will (mis)report that your server is not vulnerable if this module is not present. This vulnerability is not dependent on presence or absence of that module.
> 
> Planning:
> -------------
> This advisory will be updated when new information, a patch or a new release is available. A patch or new apache release for Apache 2.0 and 2.2 is expected in the next 48 hours. Note that, while popular, Apache 1.3 is deprecated.
> 


Re: VOTES please -- CVE-2011-3192: Range header DoS vulnerability in Apache 1.3 and Apache 2 (Final-6)

Posted by Dirk-Willem van Gulik <di...@webweaving.org>.
Various suggest on-list and off-list fixes applied. Thanks all.

A few more +1's would be nice :)

Dw.





Title:    CVE-2011-3192: Range header DoS vulnerability Apache HTTPD 1.3/2.x
          Apache HTTPD Security ADVISORY

Date:     20110824 1600Z
Product:  Apache HTTPD Web Server
Versions: Apache 1.3 all versions, Apache 2 all versions

Description:
------------

A denial of service vulnerability has been found in the way the multiple overlapping ranges are handled by the Apache HTTPD server:

     http://seclists.org/fulldisclosure/2011/Aug/175  

An attack tool is circulating in the wild. Active use of this tools has been observed.

The attack can be done remotely and with a modest number of requests can cause very significant memory and CPU usage on the server. 

The default Apache HTTPD installation is vulnerable.

There is currently no patch/new version of Apache HTTPD which fixes this vulnerability. This advisory will be updated when a long term fix is available. 

A full fix is expected in the next 48 hours. 

Mitigation:
------------

However there are several immediate options to mitigate this issue until that time. 

1) Use mod_rewrite to limit the number of ranges:

   Option 1:
          # drop Range header when more than 5 ranges.
          # CVE-2011-3192
          SetEnvIf Range (,.*?){5,} bad-range=1
          RequestHeader unset Range env=bad-range

          # optional logging.
          CustomLog logs/range-CVE-2011-3192.log common env=bad-range

   Option 2:
          # Reject request when more than 5 ranges in the Range: header.
          # CVE-2011-3192
          #
          RewriteCond %{HTTP:range} !(^bytes=[^,]+(,[^,]+){0,4}$|^$)
          RewriteRule .* - [F]

   The number 5 is arbitrary. Several 10's should not be an issue and may be
   required for sites which for example serve PDFs to very high end eReaders
   or use things such complex http based video streaming.

2) Limit the size of the request field to a few hundred bytes. Note that while this
   keeps the offending Range header short - it may break other headers; such as 
   sizeable cookies or security fields. 

          LimitRequestFieldSize 200

   Note that as the attack evolves in the field you are likely to have
   to further limit this and/or impose other LimitRequestFields limits.

   See: http://httpd.apache.org/docs/2.2/mod/core.html#limitrequestfieldsize

3) Use mod_headers to completely dis-allow the use of Range headers:

          RequestHeader unset Range 

   Note that this may break certain clients - such as those used for
   e-Readers and progressive/http-streaming video.

4) Deploy a Range header count module as a temporary stopgap measure:

     http://people.apache.org/~dirkx/mod_rangecnt.c

   Precompiled binaries for some platforms are available at:

	http://people.apache.org/~dirkx/BINARIES.txt

5) Apply any of the current patches under discussion - such as:

   http://mail-archives.apache.org/mod_mbox/httpd-dev/201108.mbox/%3cCAAPSnn2PO-d-C4nQt_TES2RRWiZr7urefhTKPWBC1b+K1Dqc7g@mail.gmail.com%3e

Actions:
-----------
Apache HTTPD users who are concerned about a DoS attack against their server should consider implementing any of the above mitigations immediately. 

When using a third party attack tool to verify vulnerability - know that most of the versions in the wild currently check for the presence of mod_deflate; and will (mis)report that your server is not vulnerable if this module is not present. This vulnerability is not dependent on presence or absence of that module.

Planning:
-------------
This advisory will be updated when new information, a patch or a new release is available. A patch or new apache release for Apache 2.0 and 2.2 is expected in the next 48 hours. Note that, while popular, Apache 1.3 is deprecated.


Re: VOTES please -- CVE-2011-3192: Range header DoS vulnerability in Apache 1.3 and Apache 2 (Final-5)

Posted by Eric Covener <co...@gmail.com>.
> CustomLog logs/range.log "%r %{Range}i" env=bad-range
>

Actually I was only using that to show/debug the result of the
directives, did not occur that folks would also want to log these!

Of course that makes sense though.

Unfortunately we lose the range header in the log when we zap it, so
logging it is not really so useful in concert with the conditional.
so probably just wise to collect them under common logformat:

SetEnvIf Range (,[^,]*){5,} bad-range=1
RequestHeader unset Range env=bad-range
CustomLog logs/range.log common env=bad-range


-- 
Eric Covener
covener@gmail.com

RE: VOTES please -- CVE-2011-3192: Range header DoS vulnerability in Apache 1.3 and Apache 2 (Final-5)

Posted by "Plüm, Rüdiger, VF-Group" <ru...@vodafone.com>.
 

> -----Original Message-----
> From: Dirk-Willem van Gulik [mailto:dirkx@webweaving.org] 
> Sent: Mittwoch, 24. August 2011 16:36
> To: dev@httpd.apache.org
> Subject: VOTES please -- CVE-2011-3192: Range header DoS 
> vulnerability in Apache 1.3 and Apache 2 (Final-5)
> 
> Folks,
> 
> Can I have a few +1's on below - or feedback on what we'd 
> like to have changed ?
> 
> *	Would like to get this out in an hour or so ?
> 
> *	FIne with the 48 hours commitment of an update ?
> 
> Dw.
> 
> 
> 
> Title:    CVE-2011-3192: Range header DoS vulnerability 
> Apache HTTPD 1.3/2.x
> Date:     20110824 1600Z
> Product:  Apache HTTPD Web Server
> Versions: Apache 1.3 all versions, Apache 2 all versions
> 
> Description:
> ------------
> 
> A denial of service vulnerability has been found in the way 
> the multiple overlapping ranges are handled by the Apache 
> HTTPD server:
> 
>      http://seclists.org/fulldisclosure/2011/Aug/175  
> 
> An attack tool is circulating in the wild. Active use of this 
> tools has been observed.
> 
> The attack can be done remotely and with a modest number of 
> requests can cause very significant memory and CPU usage on 
> the server. 
> 
> The default Apache HTTPD installation is vulnerable.
> 
> There is currently no patch/new version of Apache HTTPD which 
> fixes this vulnerability. This advisory will be updated when 
> a long term fix is available. 
> 
> A full fix is expected in the next 48 hours. 
> 
> Mitigation:
> ------------
> 
> However there are several immediate options to mitigate this 
> issue until that time:
> 
> 1) Use mod_rewrite to limit the number of ranges:
> 
>    Option 1L
>           RewriteCond %{HTTP:range} !(^bytes=[^,]+(,[^,]+){0,4}$|^$)
>           RewriteRule .* - [F]
> 
>    Option 2:
>           SetEnvIf Range (,.*?){5,} bad-range=1
>           RequestHeader unset Range env=bad-range
>           # optional logging.
>           CustomLog logs/range.log "%r %{Range}i %{bad-range}e"

Shouldn't it be a conditional logging?

CustomLog logs/range.log "%r %{Range}i" env=bad-range

Otherwise looks good. +1.

Regards

Rüdiger



VOTES please -- CVE-2011-3192: Range header DoS vulnerability in Apache 1.3 and Apache 2 (Final-5)

Posted by Dirk-Willem van Gulik <di...@webweaving.org>.
Folks,

Can I have a few +1's on below - or feedback on what we'd like to have changed ?

*	Would like to get this out in an hour or so ?

*	FIne with the 48 hours commitment of an update ?

Dw.



Title:    CVE-2011-3192: Range header DoS vulnerability Apache HTTPD 1.3/2.x
Date:     20110824 1600Z
Product:  Apache HTTPD Web Server
Versions: Apache 1.3 all versions, Apache 2 all versions

Description:
------------

A denial of service vulnerability has been found in the way the multiple overlapping ranges are handled by the Apache HTTPD server:

     http://seclists.org/fulldisclosure/2011/Aug/175  

An attack tool is circulating in the wild. Active use of this tools has been observed.

The attack can be done remotely and with a modest number of requests can cause very significant memory and CPU usage on the server. 

The default Apache HTTPD installation is vulnerable.

There is currently no patch/new version of Apache HTTPD which fixes this vulnerability. This advisory will be updated when a long term fix is available. 

A full fix is expected in the next 48 hours. 

Mitigation:
------------

However there are several immediate options to mitigate this issue until that time:

1) Use mod_rewrite to limit the number of ranges:

   Option 1L
          RewriteCond %{HTTP:range} !(^bytes=[^,]+(,[^,]+){0,4}$|^$)
          RewriteRule .* - [F]

   Option 2:
          SetEnvIf Range (,.*?){5,} bad-range=1
          RequestHeader unset Range env=bad-range
          # optional logging.
          CustomLog logs/range.log "%r %{Range}i %{bad-range}e"

2) Limit the size of the request field to a few hundred bytes. Note that while this
   keeps the offending Range header short - it may break other headers; such as 
   sizeable cookies or security fields. 

          LimitRequestFieldSize 200

   Note that as the attack evolves in the field you are likely to have
   to further limit this and/or impose other LimitRequestFields limits.

   See:      http://httpd.apache.org/docs/2.2/mod/core.html#limitrequestfieldsize

3) Use mod_headers to dis-allow the use of Range headers:

          RequestHeader unset Range 

   Note that this may break certain clients - such as those used for
   e-Readers and progressive/http-streaming video.

4) Deploy a Range header count module as a temporary stopgap measure:

     http://people.apache.org/~dirkx/mod_rangecnt.c

5) Apply any of the current patches under discussion - such as:

   http://mail-archives.apache.org/mod_mbox/httpd-dev/201108.mbox/%3cCAAPSnn2PO-d-C4nQt_TES2RRWiZr7urefhTKPWBC1b+K1Dqc7g@mail.gmail.com%3e

Actions:
-----------
Apache HTTPD users who are concerned about a DoS attack against their server should consider implementing any of the above mitigations immediately. 

When using a third party attack tool to verify vulnerability - know that most of the versions in the wild currently check for the presence of mod_deflate; and will (mis)report that your server is not vulnerable if this module is not present. This vulnerability is not dependent on presence or absence of that module.

Planning:
-------------
This advisory will be updated when a fix/patch or new release is available. A patch or new apache release for Apache 2.0 and 2.2 is expected in the next 48 hours. Note that, while popular, Apache 1.3 is deprecated.



Re: CVE-2011-3192: Range header DoS vulnerability in Apache 1.3 and Apache 2 (DRAFT-3)

Posted by Nick Kew <ni...@webthing.com>.
On Wed, 24 Aug 2011 09:30:34 -0400
Eric Covener <co...@gmail.com> wrote:

> Or more like Ruedigers:
> 
> SetEnvIf Range (,[^,]*){5,} bad-range=1

Or just
Untaint HTTP_RANGE (,[^,]*){5,}

Is it time to re-suggest dropping mod_taint into trunk?

-- 
Nick Kew

Re: CVE-2011-3192: Range header DoS vulnerability in Apache 1.3 and Apache 2 (DRAFT-3)

Posted by Eric Covener <co...@gmail.com>.
On Wed, Aug 24, 2011 at 9:29 AM, Eric Covener <co...@gmail.com> wrote:
> On Wed, Aug 24, 2011 at 9:17 AM, Eric Covener <co...@gmail.com> wrote:
>>> *       Is this the right list (and order) of the mitigations - or should ReWrite be first ?
>> FWIW I don't like rewrite first because it's so unruly with being
>> defined once per vhost + main server + RewriteEngine on.
>>
>> I like RequestHeader simplicity, and could be combined with SetEnvIf
>> to only zap long malicious looking headers.
>>
> e.g.
>
> SetEnvIf Range (,.*?){5,} bad-range=1
> RequestHeader unset Range env=bad-range
> CustomLog logs/range.log "%r %{Range}i %{bad-range}e"
>
>  printf "GET / HTTP/1.1\r\nHost:
> localhost\r\nRange:bytes=0-1,2-3,4-5,5-6,7-9,10-12,11-99,44\r\n\r\n" |
> nc localhost 80
>
>  GET / HTTP/1.1 - 1
>
> printf "GET / HTTP/1.1\r\nHost:
> localhost\r\nRange:bytes=0-1,2-3,4-5\r\n\r\n" | nc localhost 80
> GET / HTTP/1.1 bytes=0-1,2-3,4-5 -
>

Or more like Ruedigers:

SetEnvIf Range (,[^,]*){5,} bad-range=1

Re: CVE-2011-3192: Range header DoS vulnerability in Apache 1.3 and Apache 2 (DRAFT-3)

Posted by Jim Jagielski <ji...@jaguNET.com>.
+1

On Aug 24, 2011, at 10:29 AM, Plüm, Rüdiger, VF-Group wrote:

> 
> 
>> -----Original Message-----
>> From: Eric Covener [mailto:covener@gmail.com] 
>> Sent: Mittwoch, 24. August 2011 15:29
>> To: dev@httpd.apache.org
>> Subject: Re: CVE-2011-3192: Range header DoS vulnerability in 
>> Apache 1.3 and Apache 2 (DRAFT-3)
>> 
>> On Wed, Aug 24, 2011 at 9:17 AM, Eric Covener 
>> <co...@gmail.com> wrote:
>>>> *       Is this the right list (and order) of the 
>> mitigations - or should ReWrite be first ?
>>> FWIW I don't like rewrite first because it's so unruly with being
>>> defined once per vhost + main server + RewriteEngine on.
>>> 
>>> I like RequestHeader simplicity, and could be combined with SetEnvIf
>>> to only zap long malicious looking headers.
>>> 
>> e.g.
>> 
>> SetEnvIf Range (,.*?){5,} bad-range=1
>> RequestHeader unset Range env=bad-range
> 
> Nice one as well. Might be even better then the rewrite rule.
> 
> Regards
> 
> Rüdiger
> 


RE: CVE-2011-3192: Range header DoS vulnerability in Apache 1.3 and Apache 2 (DRAFT-3)

Posted by "Plüm, Rüdiger, VF-Group" <ru...@vodafone.com>.
 

> -----Original Message-----
> From: Eric Covener [mailto:covener@gmail.com] 
> Sent: Mittwoch, 24. August 2011 15:29
> To: dev@httpd.apache.org
> Subject: Re: CVE-2011-3192: Range header DoS vulnerability in 
> Apache 1.3 and Apache 2 (DRAFT-3)
> 
> On Wed, Aug 24, 2011 at 9:17 AM, Eric Covener 
> <co...@gmail.com> wrote:
> >> *       Is this the right list (and order) of the 
> mitigations - or should ReWrite be first ?
> > FWIW I don't like rewrite first because it's so unruly with being
> > defined once per vhost + main server + RewriteEngine on.
> >
> > I like RequestHeader simplicity, and could be combined with SetEnvIf
> > to only zap long malicious looking headers.
> >
> e.g.
> 
> SetEnvIf Range (,.*?){5,} bad-range=1
> RequestHeader unset Range env=bad-range

Nice one as well. Might be even better then the rewrite rule.

Regards

Rüdiger

Re: CVE-2011-3192: Range header DoS vulnerability in Apache 1.3 and Apache 2 (DRAFT-3)

Posted by Eric Covener <co...@gmail.com>.
On Wed, Aug 24, 2011 at 9:17 AM, Eric Covener <co...@gmail.com> wrote:
>> *       Is this the right list (and order) of the mitigations - or should ReWrite be first ?
> FWIW I don't like rewrite first because it's so unruly with being
> defined once per vhost + main server + RewriteEngine on.
>
> I like RequestHeader simplicity, and could be combined with SetEnvIf
> to only zap long malicious looking headers.
>
e.g.

SetEnvIf Range (,.*?){5,} bad-range=1
RequestHeader unset Range env=bad-range
CustomLog logs/range.log "%r %{Range}i %{bad-range}e"

 printf "GET / HTTP/1.1\r\nHost:
localhost\r\nRange:bytes=0-1,2-3,4-5,5-6,7-9,10-12,11-99,44\r\n\r\n" |
nc localhost 80

 GET / HTTP/1.1 - 1

printf "GET / HTTP/1.1\r\nHost:
localhost\r\nRange:bytes=0-1,2-3,4-5\r\n\r\n" | nc localhost 80
GET / HTTP/1.1 bytes=0-1,2-3,4-5 -








-- 
Eric Covener
covener@gmail.com