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

1/19/2021
06:05 PM
50%
50%

Vulnerabilities in Popular DNS Software Allow Poisoning

Seven flaws in DNSMasq have limited impact, but in combination they could be chained to create a multistaged attack.

A group of vulnerabilities in the popular DNSMasq software used for domain name system (DNS) caching and IP address assignment could allow an attacker to reroute network traffic or use nearly 1 million open forwarders on the Internet for denial-of-service (DoS) attacks.

The vulnerabilities — found by Israeli security services firm JSOF and confirmed by large technology firms including Google and Red Hat — include three vulnerabilities that allow DNS cache poisoning and four buffer-overflow vulnerabilities. Dubbed DNSpooq, the vulnerabilities could redirect people using the vulnerable DNS forwarding service, referred to as DNS cache poisoning, or be used to take over the device, JSOF stated in an advisory.

Related Content:

Many DNS Servers Still Vulnerable To Attack

Special Report: Understanding Your Cyber Attackers

New From The Edge: 4 Intriguing Email Attacks Detected by AI in 2020

While a DoS attack or device takeover could happen, DNS cache poisoning could also be used for fraud, says Shlomi Oberman, CEO at JSOF.

"If you browse to one website, but you are actually directed to another website — there could be all kinds of fraud," he says. "The worse-case scenario is cache poisoning and a remote execution attack."

A collection of software and device makers have tackled the issues in a working group for months. The vulnerabilities affect software and network appliances from at least 16 vendors, including Cisco, Digi International, Netgear, Red Hat, and Siemens. DNSMasq, which was authored by network expert Simon Kelley, patched the issues about four weeks ago but released the update — version 2.83 — on Sunday, according to the project's log files

The cache poisoning flaws make a redirection attack more probable but not certain, according to statements by Red Hat in its advisory.

"These flaws substantially reduce the number of attempts an attacker has to make to guess the 16-bit identifier and the specific UDP port used for a particular DNS query," the company states. "Considering the attack is not deterministic and requires some time to guess the right combination of values, an attacker needs a dnsmasq client to start performing many DNS queries to an attacker-chosen domain."

The attack has some relation to widespread vulnerabilities found in DNS software more than 13 years ago. Unlike the more recent issues, those vulnerabilities — found by security research Dan Kaminsky — were caused by design issues that could be exploited in concert. While there have not been attacks in the wild using the latest set of vulnerabilities, attackers started using the Kaminsky vulnerabilities in attacks within the month, suggesting the utility of cache poisoning flaws may make them a high-priority issue.

The threat posed by the vulnerabilities is uncertain. In the past, home users rarely, if ever, patched their routers. Some Internet service providers and device vendors have improved their patching process, but patching is still very spotty, Shlomi says. 

"This is relatively easy to pull off, and home routers are not updated that frequently," he says. "So home networks will likely be attacked."

Android devices also use DNSMasq for routing network traffic when in hotspot mode, Shlomi says. Attacking those devices would require proximity, limiting the impact of the vulnerabilities.

Companies, however, have to worry about workers connecting from home to the business network and cloud services but who may have a vulnerable home router. The lack of visibility most companies have into the current distributed workforce's security posture will likely make the vulnerabilities harder to eradicate. And workers who connect to the corporate network through a virtual private network could give an attacker a bridge into the network, Shlomi says. 

"Remote work makes it a lot more difficult," he says. "Oftentimes, browsing to just your corporate website may not be as secure as browsing to sites on the Internet because their certificate might be self-signed or not valid."

Companies also have to worry about attackers gaining the ability to use the Internet's open DNS forwarding servers to route traffic into a distributed denial-of-service (DDoS) attack against a specific target. 

"Calculations show that the size of the attack could be on the same order of magnitude as the biggest DDoS attacks performed to date," JSOF stated in its analysis.

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
News
Former CISA Director Chris Krebs Discusses Risk Management & Threat Intel
Kelly Sheridan, Staff Editor, Dark Reading,  2/23/2021
Edge-DRsplash-10-edge-articles
Security + Fraud Protection: Your One-Two Punch Against Cyberattacks
Joshua Goldfarb, Director of Product Management at F5,  2/23/2021
News
Cybercrime Groups More Prolific, Focus on Healthcare in 2020
Robert Lemos, Contributing Writer,  2/22/2021
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Write a Caption, Win an Amazon Gift Card! Click Here
Latest Comment: This comment is waiting for review by our moderators.
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
Building the SOC of the Future
Building the SOC of the Future
Digital transformation, cloud-focused attacks, and a worldwide pandemic. The past year has changed the way business works and the way security teams operate. There is no going back.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2020-8032
PUBLISHED: 2021-02-25
A Insecure Temporary File vulnerability in the packaging of cyrus-sasl of openSUSE Factory allows local attackers to escalate to root. This issue affects: openSUSE Factory cyrus-sasl version 2.1.27-4.2 and prior versions.
CVE-2020-36254
PUBLISHED: 2021-02-25
scp.c in Dropbear before 2020.79 mishandles the filename of . or an empty filename, a related issue to CVE-2018-20685.
CVE-2021-27670
PUBLISHED: 2021-02-25
Appspace 6.2.4 allows SSRF via the api/v1/core/proxy/jsonprequest url parameter.
CVE-2021-27671
PUBLISHED: 2021-02-25
An issue was discovered in the comrak crate before 0.9.1 for Rust. XSS can occur because the protection mechanism for data: and javascript: URIs is case-sensitive, allowing (for example) Data: to be used in an attack.
CVE-2020-9051
PUBLISHED: 2021-02-24
** REJECT ** DO NOT USE THIS CANDIDATE NUMBER. ConsultIDs: none. Reason: The CNA or individual who requested this candidate did not associate it with any vulnerability during 2020. Notes: none.