Attacks/Breaches
8/30/2007
10:00 AM
50%
50%

When Web Servers Attack

Even in a DMZ, a Web server can be a dangerous weapon

6:00 AM -- Web technology has added lots of complexity to security. Aside from issues of design, secure coding, and protecting user information, Web technology gives rise to a number of new threats. One such threat is using the Web server as a proxy to hack other devices on the same network.

Using one machine to scan or attack another isn't a new concept. For instance, take the concept of idle scan, which uses one machine to do reconnaissance on a target using TCP sequencing.

Just this week, I published a paper on a new attack that takes place via a Web server running in a DMZ. That DMZ may have many machines sitting in it -- development machines, database machines, staging machines, QA machines, customer machines, and others -- connected by the same network. In many cases, this is the most important part of the network to penetrate, because often, this is where all of the most important corporate assets live.

DMZs often are improperly built, allowing any machine on the network to connect out to the world. This configuration makes patch management and software downloading easy, but it also opens up those devices to attack.

Because the Web server and the other devices coexist on a common LAN in the DMZ, we can use the Web server to attack the other devices. For example, we can employ image-uploading scripts that pull content from the Internet.

Figure 1:

In this example, instead of requesting something on the Internet, we request something from the intranet -- or the same LAN that the DMZ lives on. Because the request doesn't actually have to be an image, we can ask the Web server to perform PHP remote file includes, command injection, or injection of an xp_cmdshell via SQL injection.

Once the Web server attacks the other machine on the same network, that machine can connect back out to the Internet and make a connection with the attacker. The attacker now has the ability to execute any command he wants on a server in the DMZ.

Although this situation is not common, it exemplifies one of the security oddities presented by modern Web design, which is sometimes done without an understanding of good network design. Simple egress filtering at the firewall -- or insuring the software you use to download images does not allow connections to internal address spaces -- could fix this issue.

The real question is: How many people will take the initiative and fix these vulnerabilities before the bad guys find them?

— RSnake is a red-blooded lumberjack whose rants can also be found at Ha.ckers and F*the.net. Special to Dark Reading

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Write a Caption, Win a Starbucks Card! Click Here
Latest Comment: "Why else would HR ask me if I have a handicap?"
Current Issue
The Changing Face of Identity Management
Mobility and cloud services are altering the concept of user identity. Here are some ways to keep up.
Flash Poll
Slideshows
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2013-7445
Published: 2015-10-15
The Direct Rendering Manager (DRM) subsystem in the Linux kernel through 4.x mishandles requests for Graphics Execution Manager (GEM) objects, which allows context-dependent attackers to cause a denial of service (memory consumption) via an application that processes graphics data, as demonstrated b...

CVE-2015-4948
Published: 2015-10-15
netstat in IBM AIX 5.3, 6.1, and 7.1 and VIOS 2.2.x, when a fibre channel adapter is used, allows local users to gain privileges via unspecified vectors.

CVE-2015-5660
Published: 2015-10-15
Cross-site request forgery (CSRF) vulnerability in eXtplorer before 2.1.8 allows remote attackers to hijack the authentication of arbitrary users for requests that execute PHP code.

CVE-2015-6003
Published: 2015-10-15
Directory traversal vulnerability in QNAP QTS before 4.1.4 build 0910 and 4.2.x before 4.2.0 RC2 build 0910, when AFP is enabled, allows remote attackers to read or write to arbitrary files by leveraging access to an OS X (1) user or (2) guest account.

CVE-2015-6333
Published: 2015-10-15
Cisco Application Policy Infrastructure Controller (APIC) 1.1j allows local users to gain privileges via vectors involving addition of an SSH key, aka Bug ID CSCuw46076.

Dark Reading Radio
Archived Dark Reading Radio

The cybersecurity profession struggles to retain women (figures range from 10 to 20 percent). It's particularly worrisome for an industry with a rapidly growing number of vacant positions.

So why does the shortage of women continue to be worse in security than in other IT sectors? How can men in infosec be better allies for women; and how can women be better allies for one another? What is the industry doing to fix the problem -- what's working, and what isn't?

Is this really a problem at all? Are the low numbers simply an indication that women do not want to be in cybersecurity, and is it possible that more women will never want to be in cybersecurity? How many women would we need to see in the industry to declare success?

Join Dark Reading senior editor Sara Peters and guests Angela Knox of Cloudmark, Barrett Sellers of Arbor Networks, Regina Wallace-Jones of Facebook, Steve Christey Coley of MITRE, and Chris Roosenraad of M3AAWG on Wednesday, July 13 at 1 p.m. Eastern Time to discuss all this and more.