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

Researchers Raise Alarm Over New Iteration of Coreflood Botnet

Password-stealing Trojan is spreading like a worm - and targeted directly at the enterprise

The seven-year-old Coreflood botnet is quietly stealing thousands of passwords from corporate users and other large organizations, thanks to recent enhancements that allow it to spread like a worm, researchers say.

The enhancements were revealed June 30 by botnet expert Joe Stewart, director of malware research at SecureWorks. Stewart traced the botnet to a single command and control server that held more than 400,000 user IDs, passwords, and other information. (See SecureWorks Finds Massive Cache of Stolen Data.)

Since then, other researchers have had an opportunity to evaluate Stewart's findings, and they don't like what they see. In a nutshell, Coreflood has combined its old ability to deliver a password-stealing Trojan with a new ability to infect whole Windows domains in a matter of hours.

"This is potentially way more malicious than Storm, because it is collecting passwords -- rather than just sending out spam or denying service -- and because the user doesn't have to click on a link or do anything at all in order to be infected," says David Jevans, CEO of security vendor IronKey and chairman of the Anti-Phishing Working Group.

Coreflood, which started out as a simple Trojan in late 2001, has been reiterated more than 100 times during its long lifespan. But with the enhancements, the Trojan now has the ability to infect Windows administrators' machines and then use their privileges to infect all of the other machines in the administrator's domain.

"We've literally seen situations where there was only one machine infected, and within a few hours, 30,000 other machines on the same network were also infected," Jevans says. "And these aren't random infections -- if it gets through to one administrator's machine, then all of the devices in his domain will be infected."

Coreflood can be shut off with an antivirus signature that prevents it from spreading. "The problem is that it's a password stealer," Jevans observes. "Most of the damage is done as soon as you're infected. It doesn't do much good to use a signature-based defense to shut it down hours or days later, after it's already got all your passwords."

Jevans is concerned that Coreflood will quickly become an attractive attack vector for cybercriminals, who want identity data from a highly qualified base of victims. "This is targeting corporate environments, which means there aren't any kids logging on to play Webkinz," he notes. "But a lot of adults access their bank accounts from the office."

The Coreflood vulnerability takes advantage of lax security practices in the Windows environment, where systems administrators often have broad rights to distribute software and other code, but whose authentication methods are simple, and even shared, Jevans observes. "And often, the domain administrator uses the same computer for surfing the Web that he does for sending out software," he notes. "It's relatively easy to find that one administrator who can infect a whole domain."

To defend themselves against Coreflood, enterprises should take a closer look at the way their Windows administrators operate, and which machines they use. Companies should also consider using anti-malware tools that are behavior-based, rather than signature-based, Jevans says.

Enterprises should also consider using anti-malware strategies that employ virtual machines, protecting the original operating system from attack, Jevans suggests. Azure, the hardware-based tool scheduled to be released next month by researchers at Damballa, is a good example of the way next-generation malware defenses might work, he says. (See Researcher Offers Malware Analysis Tool.)

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.
  • IronKey Inc.
  • SecureWorks Inc.

    Tim Wilson is Editor in Chief and co-founder of Dark Reading.com, UBM Tech's online community for information security professionals. He is responsible for managing the site, assigning and editing content, and writing breaking news stories. Wilson has been recognized as one ... View Full Bio

    Comment  | 
    Print  | 
    More Insights
  • Comments
    Newest First  |  Oldest First  |  Threaded View
    Look Beyond the 'Big 5' in Cyberattacks
    Robert Lemos, Contributing Writer,  11/25/2020
    Why Vulnerable Code Is Shipped Knowingly
    Chris Eng, Chief Research Officer, Veracode,  11/30/2020
    Register for Dark Reading Newsletters
    White Papers
    Video
    Cartoon Contest
    Write a Caption, Win an Amazon Gift Card! Click Here
    Latest Comment: I think the boss is bing watching '70s TV shows again!
    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
    Twitter Feed
    Dark Reading - Bug Report
    Bug Report
    Enterprise Vulnerabilities
    From DHS/US-CERT's National Vulnerability Database
    CVE-2020-29458
    PUBLISHED: 2020-12-02
    Textpattern CMS 4.6.2 allows CSRF via the prefs subsystem.
    CVE-2020-29456
    PUBLISHED: 2020-12-02
    Multiple cross-site scripting (XSS) vulnerabilities in Papermerge before 1.5.2 allow remote attackers to inject arbitrary web script or HTML via the rename, tag, upload, or create folder function. The payload can be in a folder, a tag, or a document's filename. If email consumption is configured in ...
    CVE-2020-5423
    PUBLISHED: 2020-12-02
    CAPI (Cloud Controller) versions prior to 1.101.0 are vulnerable to a denial-of-service attack in which an unauthenticated malicious attacker can send specially-crafted YAML files to certain endpoints, causing the YAML parser to consume excessive CPU and RAM.
    CVE-2020-29454
    PUBLISHED: 2020-12-02
    Editors/LogViewerController.cs in Umbraco through 8.9.1 allows a user to visit a logviewer endpoint even if they lack Applications.Settings access.
    CVE-2020-7199
    PUBLISHED: 2020-12-02
    A security vulnerability has been identified in the HPE Edgeline Infrastructure Manager, also known as HPE Edgeline Infrastructure Management Software. The vulnerability could be remotely exploited to bypass remote authentication leading to execution of arbitrary commands, gaining privileged access,...