February 2006

Recursive DNS servers as a growing DDoS problem

hi guys.

we discussed recursive dns servers before (servers which allow to query anything – including what they are not authoritative for, through them).

the attack currently in the wild is a lot bigger and more complicated than this, but to begin, here is an explanation (by metaphor) of that part:

spoofed icmp attacks have been around for a while. how many of us still get quite a bit of icmp echo replies stopped at our borders? these replies come to us due to spoofed attacks using our addresses.

now, imagine it – only bigger:

introduce an amplification effect.

as bigger udp packets will be fragmented by the servers, and udp obviously does not do any handshake and can easily be spoofed…
the server receives a large packet, breaks it down to several fragments and moves the query on.
that’s where the amplification effect starts.

both the attacked server and the unwilling participant in the attack, the recursive servers, experience a serious dns denial of service that keeps getting amplified considerably.

one of the problems is obviously the spoofing. let us, metaphorically and wrongly treat it for a minute as the remote exploit.

the second part of this problem is the recursive server, which for the moment we will wrongly treat as the local exploit.

obviously both need to be fixed. which is easier i am not so sure.

in the past, most network operators refused to implement best practices such as bcp38 (go fergie!) because they saw no reason for the hassle. returning back to: “if it isn’t being exploited right now, why should i worry about it?”

well, it is being exploited now, and will be further exploited in the future. combating spoofing on the internet is indeed important and now becoming critical.

removing the spoofing part for a second, the attack vector for this can easily be replaced, as one example, with a botnet.

a million trojaned hosts sending in even one packet a minute would cause quite a buzz – and do. now amplify the effect by the recursive servers and…

so, putting the spoofing aside, what do we do about our recursive servers?

there are some good url’s for that, here are some:

the recursive behaviour is necessary for some authoritative servers, but not for all. as a best practice for organizations, as an example, the server facing the world should not also be the one facing your organization (your users/clients). limiting this ability to your network space is also a good idea.

if you would like to check for yourselves, here is a message from duane wessels [1] to the dns-operations [2] mailing list where this is currently being discussed:

if anyone has the need to test particular addresses for the presence of open resolvers, please feel free to use this tool:


it will send a single “recursion desired” query to a target address.
if that query is forwarded to our authoritative server, the host has an open resolver running at that address.

dan (da man) kaminsky and mike schiffman have done some impressive work on this subject, outlined in dan’s latest shmoocon talk.
they found ~580k open resolvers:
http://deluvian.doxpara.com/, http://www.doxpara.com/

i suggest those of us who need more information or help go to the dns-operations mailing list from oarc (see below) and ask the experts there, now that this is finally public.


full technical details on how the attack works at:

gadi evron,

[1] duane wessels – dns genius and among other accomplishments the author of dns top.
[2] dns-operations – http://lists.oarci.net/mailman/listinfo/dns-operations

[changed title from: recursive dns servers ddos as a growing ddos problem]

Microsoft and week-lasting Security Advisory fix process [UPDATED]

The fixing process of Microsoft Security Advisories page is not the fastest I have seen.

On 16th February I noticed several mysterious non-working links at advisory Vulnerability in Windows Service ACLs. Service Pack download links and the CVE-2006-0023 reference pointed to the following target directory:

www.microsoft.com/Local Settings/Temporary Internet Files/Local Settings/Temporary Internet Files/OLK4D

and its subdirectories. All folders located at OLK4D were named as ‘H’, J’ etc. Like we now, Windows uses names of these type when generating subdirectories to Temporary Internet Files folder. You can’t see these in Windows Explorer, you have to use Command Prompt, DIR/A is worth of trying πŸ˜‰

I have informed MSRC immediately after noticing of these errors. No need to say that clicking these links generated a typical “We’re sorry, the page you requested could not be found” 404 page. Microsoft fixed these links on Friday, Feb 24th, after _eight_ days.

There was a similar case related to Sober advisory #912920 earlier too. AV vendor links pointed to the Desktop folder. For example, McAfee’s W32/Sober link pointed to


When visiting these links they were being redirected to Desktop Deployment page www.microsoft.com/technet/desktopdeployment/default.mspx. Odd.
I checked the HTML source code too and this was the result:

Real Symantec’s URL


pointed to


The next question is if these directories were from the internal publishing system or directories in workstations used in publishing process.

Update: Added information about previous issue in Sober.X Security Advisory 912920 etc.

Enron – the pain keeps coming

Note: I posted this to slashdot along with proof of the Private data. It has not yet been approved.

A year (or more) ago, a large batch of Enron emails were released to the public. This data set has been very useful from a ‘Research’ perspective. Just this weekend, I was using it to test the speed of PCRE vs Python vs Perl…until I happened upon a little nugget of information which led me to look at the dataset from a Security/Privacy perspective.

It appears as if data is included within these emails which violates individual Privacy. The data includes, but is not limited to, Account information to non-Enron applications (FTP login credentials, web credentials, etc.), Parent-teacher school data, private residence addresses, private residence phone numbers, Names and Social Security Numbers, and more.

Where did the Enron emails come from? The United States Federal Energy Regulatory Commission. That’s sad.

Some examples (I stripped out the SSN or Credit Card number with X’s, and changed the name/address):

A Social Security Number

To: Patti Thompson/HOU/ECT@ECT
cc: Sally Beck/HOU/ECT@ECT, Shelly Jones/HOU/ECT@ECT
Subject: Summer Intern Information


The following intern will be in Sally’s department this summer:

Name Start Date SS#

Jane Doe May 22, 2000 XXX-XX-XXXX

Please let me know the CO# and Cost Center#.

If you have any questions, I can be reached at x35850.

Thank you.


Another Social Security Number

From: christina.valdez@enron.com
Subject: Tom Hopwood
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

Badge #15518 – SS # XXX-XX-XXXX

A Credit Card purchase

Date: Thu, 10 May 2001 08:07:00 -0700 (PDT)
From: john.arnold@enron.com
To: ticketwarehouse@aol.com
Subject: Re: eBay End of Auction – Item # 1236142249
Mime-Version: 1.0^
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

199.99+ $18 o/n shipping = 217.99

Visa 4128 XXXX XXXX XXXX exp X/XX

shipping and billing address :
John Arnold
Houston, TX 77002

Reports say OS X 10.4.5 cracked for non-Apple Intel PCs

According to new RealTechNews article

“… today a hacker named Maxxuss released a patch which updates MacOS to 10.4.5 and enables it to run on non-Apple Intel-based PCs.”

This hasn’t been covered in the news at all, in fact.

The article links to Maxxuss Release Announcements page, which has ‘Last Updated: 23-Feb-2006‘ information, in fact.

The weblog of Maxxuss, announcing ‘non-official information on Mac OS X for the x86 platform’, is located at maxxuss.theblog.cc.

This was only a week after news about a poetry Don’t-Steal-Mac-OS-X embedded into OS X.

Bypassing SSL in Phishing

here is a bit of “new stuff” (now old) that now becomes partially public from our friends at f-secure, and is very disturbing.

rootkits, ssl and phishing:

haxdoor is one of the most advanced rootkit malware out there. it is a kernel-mode rootkit, but most of its hooks are in user-mode. it actually injects its hooks to the user-mode from the kernel — which is really unique and kind of bizarre.

so, why doesn’t haxdoor just hook system calls in the kernel? a recent secure science paper has a good explanation for this. haxdoor is used for phishing and pharming attacks against online banks. pharming, according to anti-phishing working group (apwg), is an attack that misdirects users to fraudulent sites or proxy servers, typically through dns hijacking or poisoning.

we took a careful look at backdoor.win32.haxdoor.gh (detection added 31 jan, 2006). it hooks http functionality, redirects traffic, steals private information, and transmits the stolen data to a web-server controlled by the attacker. most (all?) online banks use ssl encrypted connections to protect transmissions. if haxdoor would hook networking functionality in the kernel, it would have hard time phishing since the data would be encrypted. by hooking on a high-enough api level it is able to grab the data before it gets encrypted. apparently haxdoor is designed to steal data especially from ie users, and not all tricks it plays work against, for example, firefox.

financial organizations that rely on encryption for security of web transactions can contact me for details on who to actually contact on answers if they haven’t been contacted by now, as this is the least of their worries.

gadi evron,

[corrected the title from: bypassing ssh in phishing]

Several bugs fixed in – Bugzilla

Several security advisories have been released about three fixed security issues on the Bugzilla bug-tracking system. Even systems developed for software bug tracking purposes have their own bugs. πŸ˜‰

More details about these issues is located at new Secunia’s SA18979 advisory (all issues described), BID16738 (Whinedays parameter issue) and BID16745 (user credential redirect issue). There is no separate Bugtraq ID related to RSS reader title encoding issue (this is more a XSS issue related to RSS readers than bug in Bugzilla itself). A more detailed description about SQL injection type ‘Whinedays’ issue is located at Bugzilla Bug #312498 entry. Secunia’s severity level is Moderately Critical; 3/5. It seems that this vulnerability report is the first rated as Moderately Critical after December, 2003 (Secunia’s Product database has more details if You are interested). FrSIRT rated these issues as Moderate Risk.

From the SA18979 advisory:

#1: Input passed to the “whinedays” parameter in “editparams.cgi” isn’t properly sanitised before being used in a SQL query.
What are the risks of this vulnerability?
This can be exploited to manipulate SQL queries by injecting arbitrary SQL code.
#2: The problem is that some RSS readers decodes encoded HTML in feed titles.

What are the risks of this vulnerability?
This can be exploited to inject arbitrary HTML and script code, which will be executed in a user’s RSS readers session in context of an affected site when the malicious user data is viewed.
#3: The problem is that users may send login requests to an incorrect web site when the URL contains a double slash in the path name.

And what are the risks?
Successful exploitation requires that the login page is a subdirectory of the web root and that the subdirectory is a resolvable address on the user’s network.

Original Bugzilla Security Advisory is located at www.bugzilla.org/security/2.18.4. Because of range of these issues all Bugzilla installations are reportedly advised to upgrade to the latest stable version 2.20.1. The Bugzilla advisory lists old Bugzilla 2.16.x versions as immune, however.

This is interesting:
Related to RSS reader encoding issue Bugzilla “prefers to shift to Atom feeds, where the RFC is unambiguous about HTML markup in feed titles”.

The reporters of these vulnerabilities live in several countries because of worldwide Bugzilla community, for example Teemu Mannermaa is from Finland. Mr. Mannermaa has discovered other Bugzilla issues earlier too, e.g. related to fixed version 2.16.11. Additionally, Myk Melez has been listed at SA17030 published in October too.
The recent Mozilla’s Bugzilla version is 2.20. Linux Kernel project uses version 2.16.10, in turn. Red Hat Bugzilla is one of the popular Bugzilla sites too. According to their Web site version 2.18-rh is in use.

Bugzilla Team didn’t only fixed security issues, the detailed Release Notes pages are located here.