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

9/15/2015
04:30 PM
Connect Directly
Twitter
LinkedIn
RSS
E-Mail
50%
50%

Backdoored Business Routers An Emerging Threat

Discovery of malicious implants in 14 Cisco routers, "tip of iceberg" FireEye says

In a troubling new development, threat actors looking for different ways to break into and remain undetected on enterprise networks appear to have begun targeting routers connecting businesses to the Internet.

Once considered a largely theoretical risk, backdoored business routers could soon pose a big problem for enterprises, security vendor FireEye warned in a report released Tuesday.

FireEye said it has discovered at least 14 instances worldwide where attackers have managed to successfully replace the firmware on Cisco business routers with a malicious implant dubbed SYNful Knock by the security vendor.

The implant is basically a clandestine modification of the router’s lOS image and allows attackers to maintain persistence on a compromised system even through reboots, FireEye said. The vendor described the implant as fully modular and customizable in design and capable of being remotely updated after installation.

The implant gives attackers a way to load different modules and executable files on the compromised router and provides attackers with unrestricted access to the system via a backdoor password.

The backdoor is extremely hard to detect on the compromised Cisco routers. It gives attackers a way to not only maintain persistence but also a way to compromise other systems and data on the network to which the router is connected, FireEye said.

According to FireEye, there is no evidence that the attackers exploited any zero-day vulnerability or other flaw to install the malicious implant on the 14 Cisco routers. Instead, the routers likely had default credentials that gave the attackers easy access to the system. Or, the attackers somehow managed to gain access to the credentials in order to install the backdoor.

The routers on which the malicious implant was discovered include the now discontinued Cisco 1841, Cisco 2811 and Cisco 3825 integrated services routers. Other models are likely vulnerable to the poisoned implant as well based on the similarity in their code base and functionality, the FireEye report noted.

However, there is no reason to conclude that only Cisco routers are being targeted with malicious firmware implants. “We believe that the detection of SYNful Knock is just the tip of the iceberg when it comes to attacks utilizing modified router images (regardless of vendor),” FireEye said.

“As attackers focus their efforts on gaining persistent access, it is likely that other undetected variants of this implant are being deployed throughout the globe.”

The threat from modified router implants of the type discovered by FireEye has been considered largely theoretical especially in actual use, the report said. But there’s evidence suggesting that a growing number of such implants are available in the wild.

As one example, the report pointed to a recent alert from Cisco warning customers about an evolution in attacks against the Cisco IOS platform.

The alert noted that Cisco had observed some instances where attackers gained physical or administrative access to a Cisco router and replaced the IOS bootstrap image with a malicious implant.

“In all cases seen by Cisco, attackers accessed the devices using valid administrative credentials,” the network giant noted. They then used a legitimate field upgrade process to install the malicious implant on their systems, Cisco said. No vulnerability was exploited in any of the cases that Cisco has seen so far, the company added.

The FireEye report outlines some measures that enterprise can take if they believe their router is compromised. The most effective measure is to reimage the router with a clean IOS image from Cisco, the company said.

“After fixing the routers, focus on the rest of the network,” FireEye said. “If the router did not have default credentials, then the infection must have occurred some other way. A compromise assessment should follow.”

 

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
Ransomware Is Not the Problem
Adam Shostack, Consultant, Entrepreneur, Technologist, Game Designer,  6/9/2021
Edge-DRsplash-11-edge-ask-the-experts
How Can I Test the Security of My Home-Office Employees' Routers?
John Bock, Senior Research Scientist,  6/7/2021
News
New Ransomware Group Claiming Connection to REvil Gang Surfaces
Jai Vijayan, Contributing Writer,  6/10/2021
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Write a Caption, Win an Amazon Gift Card! Click Here
Latest Comment: This gives a new meaning to blind leading the blind.
Current Issue
The State of Cybersecurity Incident Response
In this report learn how enterprises are building their incident response teams and processes, how they research potential compromises, how they respond to new breaches, and what tools and processes they use to remediate problems and improve their cyber defenses for the future.
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
CVE-2021-28815
PUBLISHED: 2021-06-16
Insecure storage of sensitive information has been reported to affect QNAP NAS running myQNAPcloud Link. If exploited, this vulnerability allows remote attackers to read sensitive information by accessing the unrestricted storage mechanism. This issue affects: QNAP Systems Inc. myQNAPcloud Link vers...
CVE-2021-3535
PUBLISHED: 2021-06-16
Rapid7 Nexpose is vulnerable to a non-persistent cross-site scripting vulnerability affecting the Security Console's Filtered Asset Search feature. A specific search criterion and operator combination in Filtered Asset Search could have allowed a user to pass code through the provided search field. ...
CVE-2021-32685
PUBLISHED: 2021-06-16
tEnvoy contains the PGP, NaCl, and PBKDF2 in node.js and the browser (hashing, random, encryption, decryption, signatures, conversions), used by TogaTech.org. In versions prior to 7.0.3, the `verifyWithMessage` method of `tEnvoyNaClSigningKey` always returns `true` for any signature that has a SHA-5...
CVE-2021-32623
PUBLISHED: 2021-06-16
Opencast is a free and open source solution for automated video capture and distribution. Versions of Opencast prior to 9.6 are vulnerable to the billion laughs attack, which allows an attacker to easily execute a (seemingly permanent) denial of service attack, essentially taking down Opencast using...
CVE-2021-32676
PUBLISHED: 2021-06-16
Nextcloud Talk is a fully on-premises audio/video and chat communication service. Password protected shared chats in Talk before version 9.0.10, 10.0.8 and 11.2.2 did not rotate the session cookie after a successful authentication event. It is recommended that the Nextcloud Talk App is upgraded to 9...