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.

Attacks/Breaches

5/16/2013
05:30 PM
Connect Directly
Google+
Twitter
RSS
E-Mail
50%
50%

Pushdo Botnet Morphs To Elude Hunters

U.S., other national government agencies, contractors, and military networks found housing new Pushdo bots as botnet adds stealthier features to evade detection, takedown

A botnet of botnets that has been disrupted by researchers multiple times during the past few years has been retooled with features that make its detection more difficult and its takedown nearly impossible without legal action.

The Pushdo botnet -- which provides the infrastructure for other malware and botnets and spreads a malware downloader program that, in turn, drops Cutwail, Gameover Zeus, and BlackHole Trojans -- is now employing Domain Generation Algorithm (DGA) as a resilient backup command-and-control (C&C) infrastructure, RSA encryption to prevent researchers from taking over the botnet, and phony JPEG image files to hide C&C traffic.

Researchers with Damballa, Dell Secureworks, and Georgia Institute of Technology recently teamed to study this new variant of Pushdo, which was first spotted by Damballa and its homegrown DGA detection tool. Among the victims infected by Pushdo are several U.S. and other national government agencies, government contractors, and military networks, the researchers found.

"This is the most elaborate [move by a] botnet trying to hide its own command and communications," says Brett Stone-Gross, senior security researcher at Dell Secureworks, who helped Damballa confirm the C&C traffic it had spotted using DGA was Pushdo. "They added resiliency with the DGA, and along with that they implemented RSA encryption so researchers, law enforcement, or their rivals can't control the botnet and use it against itself. They are the only ones who can control their botnet," Stone-Gross says. All researchers can do is record IP addresses and metadata, he says.

And in the latest twist today -- possibly in response to the discovery of their new techniques features -- the Pushdo gang was spotted pushing yet another variant of the malware, one that generates .kz domains instead of .com domains, according to Seculert, which also is studying Pushdo. "It seems like they noticed that they are being probed, as the variants were uploaded to the hijacked webserver few hours before the report went public," says Aviv Raff, CTO at Seculert.

Pushdo, which is run by a well-funded Eastern European cybercrime gang, boasts anywhere from 175,000 to a half-million bots each day, and is spread mainly via the massive and prolific Cutwail spam botnet. Pushdo basically acts as the infrastructure for botnet activity -- everything from traditional spam to spreading malicious Trojan like Zeus and SpyEye that steal financial credentials. It's mostly spread via the massive Cutwail botnet and has survived four takedowns in five years.

"It shows that they probably make a good amount of money through spam email. It's like any business: It's important to maintain a resilient infrastructure, and if the infrastructure goes down, you lose money," Stone-Gross says.

The addition of DGA for its backup C&C basically allows Pushdo to prevent interference with its C&C -- think blacklisting or extracting C&C domain names -- by making the C&C domain names a moving target, dynamically generating domain names, and using just one at a time, which later gets discarded.

"They are trying to build a system that's immune to takedown," says Jeremy Demar, senior researcher at Damballa. Demar says Pushdo downloads encrypted malware payloads so researchers can't analyze them or detect them.

[Pushdo botnet's spam traffic cut by 80 percent in takedown. See Major Disruption of Pushdo Botnet Wasn't The Original Goal .]

Researchers saw some 1.1 million unique IP addresses making Pushdo C&C requests in a two-month period, and around 35,000 unique IPs connect each day. Pushdo's DGA generates around 1,380 unique domain names daily.

India and Iran are home to the most Pushdo-infected machines, but Mexico, Thailand, Indonesia, and the U.S. also have Pushdo bots. An average of 23,000 unique hosts in the U.S. have tried connecting to Pushdo's DGA domain names. The government and military victims -- which are a small percentage of the overall bot population -- likely were inadvertent infections, Damballa's Demar says. "Someone downloaded an email," he says.

The malware also generates fake traffic to legitimate websites in an attempt to mask its C&C communications. "The C&C servers will also respond with a jpeg image with encrypted, embedded malware payloads to hide any additional files it wants to download," Demar wrote in a blog post.

Takedown of Pushdo would require legal intervention, the researchers say: VeriSign requires a court order before it takes action on its .com domain customers.

Damballa's full report on Pushdo is available here (PDF) for download, and Dell Secureworks' is here (PDF) for download.

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

Kelly Jackson Higgins is Executive Editor at DarkReading.com. 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
Comments
Newest First  |  Oldest First  |  Threaded View
RDP Bug Takes New Approach to Host Compromise
Kelly Sheridan, Staff Editor, Dark Reading,  7/18/2019
The Problem with Proprietary Testing: NSS Labs vs. CrowdStrike
Brian Monkman, Executive Director at NetSecOPEN,  7/19/2019
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Current Issue
Building and Managing an IT Security Operations Program
As cyber threats grow, many organizations are building security operations centers (SOCs) to improve their defenses. In this Tech Digest you will learn tips on how to get the most out of a SOC in your organization - and what to do if you can't afford to build one.
Flash Poll
The State of IT Operations and Cybersecurity Operations
The State of IT Operations and Cybersecurity Operations
Your enterprise's cyber risk may depend upon the relationship between the IT team and the security team. Heres some insight on what's working and what isn't in the data center.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2019-10101
PUBLISHED: 2019-07-23
ServiceStack ServiceStack Framework 4.5.14 is affected by: Cross Site Scripting (XSS). The impact is: JavaScrpit is reflected in the server response, hence executed by the browser. The component is: the query used in the GET request is prone. The attack vector is: Since there is no server-side valid...
CVE-2019-10102
PUBLISHED: 2019-07-23
Voice Builder Prior to commit c145d4604df67e6fc625992412eef0bf9a85e26b and f6660e6d8f0d1d931359d591dbdec580fef36d36 is affected by: CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection'). The impact is: Remote code execution with the same privileges as the...
CVE-2019-10102
PUBLISHED: 2019-07-23
Jeesite 1.2.7 is affected by: SQL Injection. The impact is: sensitive information disclosure. The component is: updateProcInsIdByBusinessId() function in src/main/java/com.thinkgem.jeesite/modules/act/ActDao.java has SQL Injection vulnerability. The attack vector is: network connectivity,authenticat...
CVE-2018-18670
PUBLISHED: 2019-07-23
GNUBOARD5 5.3.1.9 has XSS that allows remote attackers to inject arbitrary web script or HTML via the "Extra Contents" parameter, aka the adm/config_form_update.php cf_1~10 parameter.
CVE-2018-18672
PUBLISHED: 2019-07-23
GNUBOARD5 5.3.1.9 has XSS that allows remote attackers to inject arbitrary web script or HTML via the "board head contents" parameter, aka the adm/board_form_update.php bo_content_head parameter.