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

12/23/2019
04:30 PM
50%
50%

Citrix Urges Firms to Harden Configurations After Flaw Report

A vulnerability in two of the company's appliances opens 80,000 networks up for exploitation.

A vulnerability in two network appliances made by Citrix and used by an estimated 80,000 companies worldwide could be exploited to allow an attacker to gain access to a firm's local network from the internet, according to advisories published today. 

The vulnerability (CVE-2019-19781), which affects the Citrix Application Delivery Controller and Citrix Gateway, allows an unauthenticated attacker to run arbitrary code on the appliances, according to Citrix's advisory on the issue. While few details of the vulnerability have been released, Citrix did document several mitigation steps that will protect users but has not yet released a patch.

Because it is so easy to exploit and does not require authentication, the vulnerability is the highest criticality, says Mikhail Klyuchnikov, one of the three vulnerability researchers credited with finding the issue and a Web-application security specialist with vulnerability assessment firm Positive Technologies.

"It's really easy to exploit, [and] it's very reliable," Klyuchnikov says. "[We don't] know if it is being used in the wild."

Citrix appliances are often used as gateways for application load balancing and remote access. Judging from the mitigation steps, the Citrix issue appears to affect the virtual private networking component of the appliances' software. 

Of the 80,000 companies in 158 countries potentially at risk, the plurality — 38% — are based in the United States. An addition 9% are in Germany, 6% in the United Kingdom, 5% in the Netherlands, and 4% in Australia.

"Citrix applications are widely used in corporate networks," said Dmitry Serebryannikov, director of the security audit department with Positive Technologies, in a statement. "This includes their use for providing terminal access of employees to internal company applications from any device via the Internet. Considering the high risk brought by the discovered vulnerability, and how widespread Citrix software is in the business community, we recommend information security professionals take immediate steps to mitigate the threat."

Positive Technologies reported the vulnerability to Citrix in early December, according to the firm. Citrix responded quickly with risk mitigation measures, the company said. An attack can be completed in less than a minute, and some Citrix products have been vulnerable for more than five years, Positive Technologies stated.

The appliance, many sold under the NetScaler brand, is a common way to gain remote access to networks or applications, Klyuchnikov says.

"Using Citrix NetScaler to access the internal network is common practice because this software has the ability to implement SSL VPN features," he says. "This feature, for example, can be used to access the corporate network by employees who work remotely."

In its advisory on the vulnerability, security firm Symantec recommends companies block external access at the edge of the network and use intrusion detection systems to monitor links that need to be accessible. 

"If global access isn't needed, filter access to the affected computer at the network boundary," Symantec stated. "Restricting access to only trusted computers and networks might greatly reduce the likelihood of successful exploits."

This is not the first time Citrix has had to deal with a serious security weakness. In March, the FBI notified the company that attackers had breached its network and downloaded business documents.

With the latest security vulnerability, two other security experts — Gianlorenzo Cipparrone and Miguel Gonzalez of online betting service Paddy Power Betfair plc — are credited with the discovery of the issue. 

Citrix did not respond to an e-mail requesting comment.

Related Content:

Check out The Edge, Dark Reading's new section for features, threat data, and in-depth perspectives. Today's top story: "SIM Swapping Attacks: What They Are & How to Stop Them."

Veteran technology journalist of more than 20 years. Former research engineer. Written for more than two dozen publications, including CNET News.com, Dark Reading, MIT's Technology Review, Popular Science, and Wired News. Five awards for journalism, including Best Deadline ... View Full Bio
 

Recommended Reading:

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
COVID-19: Latest Security News & Commentary
Dark Reading Staff 9/17/2020
Cybersecurity Bounces Back, but Talent Still Absent
Simone Petrella, Chief Executive Officer, CyberVista,  9/16/2020
Meet the Computer Scientist Who Helped Push for Paper Ballots
Kelly Jackson Higgins, Executive Editor at Dark Reading,  9/16/2020
Register for Dark Reading Newsletters
White Papers
Video
Cartoon
Current Issue
Special Report: Computing's New Normal
This special report examines how IT security organizations have adapted to the "new normal" of computing and what the long-term effects will be. Read it and get a unique set of perspectives on issues ranging from new threats & vulnerabilities as a result of remote working to how enterprise security strategy will be affected long term.
Flash Poll
How IT Security Organizations are Attacking the Cybersecurity Problem
How IT Security Organizations are Attacking the Cybersecurity Problem
The COVID-19 pandemic turned the world -- and enterprise computing -- on end. Here's a look at how cybersecurity teams are retrenching their defense strategies, rebuilding their teams, and selecting new technologies to stop the oncoming rise of online attacks.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2020-8225
PUBLISHED: 2020-09-18
A cleartext storage of sensitive information in Nextcloud Desktop Client 2.6.4 gave away information about used proxies and their authentication credentials.
CVE-2020-8237
PUBLISHED: 2020-09-18
Prototype pollution in json-bigint npm package < 1.0.0 may lead to a denial-of-service (DoS) attack.
CVE-2020-8245
PUBLISHED: 2020-09-18
Improper Input Validation on Citrix ADC and Citrix Gateway 13.0 before 13.0-64.35, Citrix ADC and NetScaler Gateway 12.1 before 12.1-58.15, Citrix ADC 12.1-FIPS before 12.1-55.187, Citrix ADC and NetScaler Gateway 12.0, Citrix ADC and NetScaler Gateway 11.1 before 11.1-65.12, Citrix SD-WAN WANOP 11....
CVE-2020-8246
PUBLISHED: 2020-09-18
Citrix ADC and Citrix Gateway 13.0 before 13.0-64.35, Citrix ADC and NetScaler Gateway 12.1 before 12.1-58.15, Citrix ADC 12.1-FIPS before 12.1-55.187, Citrix ADC and NetScaler Gateway 12.0, Citrix ADC and NetScaler Gateway 11.1 before 11.1-65.12, Citrix SD-WAN WANOP 11.2 before 11.2.1a, Citrix SD-W...
CVE-2020-8247
PUBLISHED: 2020-09-18
Citrix ADC and Citrix Gateway 13.0 before 13.0-64.35, Citrix ADC and NetScaler Gateway 12.1 before 12.1-58.15, Citrix ADC 12.1-FIPS before 12.1-55.187, Citrix ADC and NetScaler Gateway 12.0, Citrix ADC and NetScaler Gateway 11.1 before 11.1-65.12, Citrix SD-WAN WANOP 11.2 before 11.2.1a, Citrix SD-W...