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.

Vulnerabilities / Threats //

Advanced Threats

9/24/2015
02:00 PM
Connect Directly
Twitter
LinkedIn
RSS
E-Mail
50%
50%

Cisco Offers Free Tool To Detect SYNful Knock Router Malware

Tool helps businesses detect routers running known version of newly discovered malicious implant.

Cisco Systems enterprise users now have a way to check if their network routers might have been infected by the recently disclosed SYNful Knock malware.

The company yesterday released a new Python script that organizations can use to scan their networks for potentially infected routers. The free tool works by looking for routers on the network that answer to the malware’s specific “knock,” William McVey, technical lead at Cisco’s Talos Threat Intelligence group said in a blog post.

The tool can be used to detect hosts compromised with currently known versions of SYNful Knock, McVey said. “But it cannot establish that a network does not have malware that might have evolved to use a different set of signatures,” he added in a somewhat confusingly worded caveat.

"The tool injects custom crafted packets at the Ethernet layer (layer 2) and monitors and parses the responses,” McVey said. “This functionality requires that the tool be run with root privileges.”

SYNful Knock is basically malware code that allows attackers to gain nearly undetectable and persistent remote control over certain Cisco business routers.

Security vendor FireEye, which issued an alert on the issue last week, described it as a malicious implant designed to replace and masquerade as the legitimate firmware on a handful of now discontinued Cisco router models (Cisco 1841, Cisco 2811 and Cisco 3825). Other models are likely impacted as well, FireEye said, based on its observation of the malware and the impacted systems.

SYNful Knock gives attackers complete administrative control over a compromised router via a backdoor password and provides them with a platform from which to launch attacks against other systems and routers on the same network. FireEye said it has discovered at least 14 Cisco network routers, used by businesses to connect to the Internet, infected with the poisoned implant.

Contrary to what some might expect, the attack is not the result of a security flaw in any of the affected Cisco products. Instead, in each case the attackers appear to have managed to either gain actual physical access to the devices, or used administrative credentials to break into the systems and plant the malware.

Attacks involving the swapping out and replacing of firmware in a commercial-grade router with a rogue version have up to now been considered largely theoretical. The appearance of SYNful Knock suggests otherwise and shows that threat actors have begun exploring ways to backdoor the critical network routers that organizations use to connect to the Internet.

As FireEye noted in its report last week, SYNful Knock could well be the first of a new kind of attack tactic involving the use of modified router images to gain remote control of the devices. The same kind of malicious firmware that was implanted on the Cisco routers can be loaded on routers from other vendors as well.

“Routers are one of the Holy Grail targets for attackers because they lie outside of many normal security protections,” says Lamar Bailey, leader of Tripwire's Vulnerability and Exposures Research Team. “Modifying firmware for your own needs or to add new features is a common practice and has been used to great success on home routers and access points,” Bailey says. “This is just the same practice used on a grander scale.”

 

Jai Vijayan is a seasoned technology reporter with over 20 years of experience in IT trade journalism. He was most recently a Senior Editor at Computerworld, where he covered information security and data privacy issues for the publication. Over the course of his 20-year ... View Full Bio
 

Recommended Reading:

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
Commentary
How SolarWinds Busted Up Our Assumptions About Code Signing
Dr. Jethro Beekman, Technical Director,  3/3/2021
News
'ObliqueRAT' Now Hides Behind Images on Compromised Websites
Jai Vijayan, Contributing Writer,  3/2/2021
News
Attackers Turn Struggling Software Projects Into Trojan Horses
Robert Lemos, Contributing Writer,  2/26/2021
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Write a Caption, Win an Amazon Gift Card! Click Here
Latest Comment: George has not accepted that the technology age has come to an end.
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
The State of Ransomware
The State of Ransomware
Ransomware has become one of the most prevalent new cybersecurity threats faced by today's enterprises. This new report from Dark Reading includes feedback from IT and IT security professionals about their organization's ransomware experiences, defense plans, and malware challenges. Find out what they had to say!
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2020-28466
PUBLISHED: 2021-03-07
This affects all versions of package github.com/nats-io/nats-server/server. Untrusted accounts are able to crash the server using configs that represent a service export/import cycles. Disclaimer from the maintainers: Running a NATS service which is exposed to untrusted users presents a heightened r...
CVE-2021-27364
PUBLISHED: 2021-03-07
An issue was discovered in the Linux kernel through 5.11.3. drivers/scsi/scsi_transport_iscsi.c is adversely affected by the ability of an unprivileged user to craft Netlink messages.
CVE-2021-27365
PUBLISHED: 2021-03-07
An issue was discovered in the Linux kernel through 5.11.3. Certain iSCSI data structures do not have appropriate length constraints or checks, and can exceed the PAGE_SIZE value. An unprivileged user can send a Netlink message that is associated with iSCSI, and has a length up to the maximum length...
CVE-2021-27363
PUBLISHED: 2021-03-07
An issue was discovered in the Linux kernel through 5.11.3. A kernel pointer leak can be used to determine the address of the iscsi_transport structure. When an iSCSI transport is registered with the iSCSI subsystem, the transport's handle is available to unprivileged users via the sysfs file system...
CVE-2021-26294
PUBLISHED: 2021-03-07
An issue was discovered in AfterLogic Aurora through 7.7.9 and WebMail Pro through 7.7.9. They allow directory traversal to read files (such as a data/settings/settings.xml file containing admin panel credentials), as demonstrated by dav/server.php/files/personal/%2e%2e when using the caldav_public_...