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Web Server Botnets and Server Farms as Attack Platforms
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SUMMARY
This is an article on cross platform web server malware and their massive
use as botnets, spam bots and generally as attack platforms.
DETAILS
In the February edition of the <http://www.virusbtn.com/> Virus Bulletin
magazine Kfir Damari, Noam Rathaus and Gadi Evron of
<http://www.beyondsecurity.com/> Beyond Security) wrote an article on
cross platform web server malware and their massive use as botnets, spam
bots and generally as attack platforms.
Web security papers deal mostly with secure coding and application
security. In this paper they describe how these are taken to the next
level with live attacks and operational problems service providers deal
with daily.
They discuss how these attacks work using (mainly) file inclusion
vulnerabilities (RFI) and (mainly) PHP shells.
Further, they discuss how ISPs and hosting farms suffer tremendously from
this, and what can be done to combat the threat.
Malware is often built to operate within a certain OS environment. Web
server malware is completely cross-platform (as long as a web daemon which
supports scripting can be found such as IIS, Apache, etc.). These malware
attack the web application first, and only then further compromise takes
place platform by platform, using the web server's privileges.
Most web servers are being compromised by these attacks as a result of an
insecure web application written in PHP, although attacks for other
scripting languages such as Perl and ASP are also in-the-wild.
The main reason for this is that many different PHP applications are
available online, and often freely as open source, which makes them a
popular selection for use on many web sites. Another reason for the
popularity of attacks against PHP applications is that writing securely in
PHP is very difficult, which makes most of these PHP applications
vulnerable to multiple attacks, with hundreds of new vulnerabilities
released publicly every month.
While in the past botnets used to be composed of mainly broadband end
users running Windows, today we can see more and more server botnets we
can refer to as "IIS botnets" or "Linux botnets" as a direct result of
these attacks.
One of the conclusions they reached was that although the technologies
used are not new (RFI, PHP shells, etc.) the sheer scale of the problem is
what's interesting.
In their research as detailed in the Virus Bulletin article they recognize
that vulnerabilities such as file inclusion, as simple as they may be, are
equivalent to remote code execution in effect.
Although escalation wars, which are reactive in nature, are a solution the
industry hates and is stuck with on botnets, spam, fraud and many other
fronts, this front of web server attacks stands completely unopposed and
controlled by the bad guys. In their research they detail how over-time,
when aggregated, most attacks come from the same IP addresses without
these ever getting blocked.
ISPs and hosting farms selling low-cost hosting services can not cope with
this threat, especially where an attack against one user running such an
application can compromise a server running 3000 other sites.
Another issue discussed was
<http://blogs.securiteam.com/index.php/archives/792> the formation of the
<http://www.webhoneynet.net/> Web Honeynet Task Force (renamed from the
Web Honeynet Project to avoid confusion with the honeynet project).
The paper can be found here:
<http://www.beyondsecurity.com/whitepapers/GadiEvron_VBFeb07.pdf> Web
Server Botnets and Server Farms as Attack Platforms (
<http://www.virusbtn.com/> all rights reserved to Virus Bulletin)
ADDITIONAL INFORMATION
The information has been provided by <http://www.beyondsecurity.com/>
Beyond Security.
The original paper can be found at:
<http://www.beyondsecurity.com/whitepapers/GadiEvron_VBFeb07.pdf>
http://www.beyondsecurity.com/whitepapers/GadiEvron_VBFeb07.pdf
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