Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.


06:55 AM
Connect Directly

Botnet Hunters Reveal New Spin on Old Tricks

Damballa researchers share some techniques for getting a better picture of botnets - and targeted attacks

Is that malware found on your client machine the sign of a targeted attack or a routine bot-herding run? How do you know for sure?

Botnet hunters from Damballa are using some traditional network monitoring techniques to determine the size and scope of botnets -- information that can even help distinguish between a direct attack or a random bot recruitment.

“We are working on ways to better [calculate] the numbers of these botnets with some accuracy,” says Christopher Davis, director of threat analysis for Damballa. Davis and Damballa chief scientist and co-founder David Dagon will discuss their company’s botnet research techniques at Black Hat D.C. next week.

Damballa researchers basically reverse-engineer the malware code that arrives at one of their customer’s client machines, and then study how it communicates with its command and control (C&C) server. Then, using a DNS cache-inspection technique, combined with tracking the C&C server’s IP packet identifier in TCP/IP, they can take more accurate counts of the number of bots, C&C servers, and the potential scope of a particular botnet.

Damballa is basically putting a new spin on some existing techniques. Phishers, for example, have been known to use DNS cache inspection for reconnaissance before staging an exploit on an organization. “Although these techniques have been around and known for a long time, we’ve never heard of anyone applying them to botnet research,” Davis says.

These methods are useful for bot malware that provides only limited visibility into the botnet’s inner workings, such as HTTP-based botnets. An IRC-based botnet -- or even Storm, which uses peer-to-peer communications -- wouldn’t require these techniques because they are more transparent and simpler to track, Davis says.

Learning about the size of the botnet behind a piece of malware can provide some clues as to whether it’s a targeted attack or a bot-recruiting run. “You’re never able to say 100 percent that this wasn’t a targeted attack. But generally, the bad guy isn’t likely to have a [targeted] enterprise join a 20,000-member botnet. It’s going to be a small one,” Davis says.

With DNS cache inspection, the researchers query regional servers for the “bad” domain. “We can then see if this bad domain has been requested there…it wouldn’t be in the cache if no one else had asked for it,” Davis says.

So if an Atlanta-based ISP’s DNS server retains the bad guy’s domain in its cache, it’s likely that users in that area are getting infected, he says. This gets them closer to learning about the range of the bot population.

Then comes the so-called IPID technique. Davis says the researchers can determine how many packets it takes for the malware’s update or download, so they can use that count to calculate roughly how many bots there are. IPID basically provides a packet counter they can refer to in each query to the C&C server. “Watching IPID, we can tell when [the C&C server] sends a command or someone downloads the malware from it,” Davis says.

The downside of these methods, however, is that they’re relatively “noisy,” Davis says, which could potentially blow the researchers’ cover and prompt the bad guys to relocate their servers. So the researchers try to keep a low profile when scanning DNS servers and when sending packets to the botnet C&C servers so their presence isn’t detected, he says. The goal is to be able to better determine growth, spread, and shifts in a botnet.

Have a comment on this story? Please click "Discuss" below. If you'd like to contact Dark Reading's editors directly, send us a message.

Damballa Inc.

Kelly Jackson Higgins is the Executive Editor of Dark Reading. She is an award-winning veteran technology and business journalist with more than two decades of experience in reporting and editing for various publications, including Network Computing, Secure Enterprise ... View Full Bio

Comment  | 
Print  | 
More Insights
Newest First  |  Oldest First  |  Threaded View
How SolarWinds Busted Up Our Assumptions About Code Signing
Dr. Jethro Beekman, Technical Director,  3/3/2021
'ObliqueRAT' Now Hides Behind Images on Compromised Websites
Jai Vijayan, Contributing Writer,  3/2/2021
Attackers Turn Struggling Software Projects Into Trojan Horses
Robert Lemos, Contributing Writer,  2/26/2021
Register for Dark Reading Newsletters
White Papers
Cartoon Contest
Write a Caption, Win an Amazon Gift Card! Click Here
Latest Comment: This comment is waiting for review by our moderators.
Current Issue
2021 Top Enterprise IT Trends
We've identified the key trends that are poised to impact the IT landscape in 2021. Find out why they're important and how they will affect you today!
Flash Poll
How Enterprises are Developing Secure Applications
How Enterprises are Developing Secure Applications
Recent breaches of third-party apps are driving many organizations to think harder about the security of their off-the-shelf software as they continue to move left in secure software development practices.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
PUBLISHED: 2021-03-04
Xerox AltaLink B8045/B8055/B8065/B8075/B8090 and C8030/C8035/C8045/C8055/C8070 multifunction printers with software releases before 101.00x.099.28200 allow an attacker to execute an unwanted binary during a exploited clone install. This requires creating a clone file and signing that file with a com...
PUBLISHED: 2021-03-04
Xerox AltaLink B8045/B8055/B8065/B8075/B8090 and C8030/C8035/C8045/C8055/C8070 multifunction printers with software releases before 101.00x.099.28200 allow a user with administrative privileges to turn off data encryption on the device, thus leaving it open to potential cryptographic information dis...
PUBLISHED: 2021-03-03
The Java client for the Datadog API before version 1.0.0-beta.9 has a local information disclosure of sensitive information downloaded via the API using the API Client. The Datadog API is executed on a unix-like system with multiple users. The API is used to download a file containing sensitive info...
PUBLISHED: 2021-03-03
resources/public/js/orchestrator.js in openark orchestrator before 3.2.4 allows XSS via the orchestrator-msg parameter.
PUBLISHED: 2021-03-03
GLPI is open source software which stands for Gestionnaire Libre de Parc Informatique and it is a Free Asset and IT Management Software package. In GLPI before verison 9.5.4, there is a vulnerability within the document upload function (Home > Management > Documents > Add, or /front/documen...