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

06:05 PM

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
Newest First  |  Oldest First  |  Threaded View
7 Old IT Things Every New InfoSec Pro Should Know
Joan Goodchild, Staff Editor,  4/20/2021
Cloud-Native Businesses Struggle With Security
Robert Lemos, Contributing Writer,  5/6/2021
Defending Against Web Scraping Attacks
Rob Simon, Principal Security Consultant at TrustedSec,  5/7/2021
Register for Dark Reading Newsletters
White Papers
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
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
PUBLISHED: 2021-05-13
Exiv2 is a C++ library and a command-line utility to read, write, delete and modify Exif, IPTC, XMP and ICC image metadata. A read of uninitialized memory was found in Exiv2 versions v0.27.3 and earlier. Exiv2 is a command-line utility and C++ library for reading, writing, deleting, and modifying th...
PUBLISHED: 2021-05-13
An issue was discovered in Prosody before 0.11.9. The proxy65 component allows open access by default, even if neither of the users has an XMPP account on the local server, allowing unrestricted use of the server's bandwidth.
PUBLISHED: 2021-05-13
An issue was discovered in Prosody before 0.11.9. Default settings are susceptible to remote unauthenticated denial-of-service (DoS) attacks via memory exhaustion when running under Lua 5.2 or Lua 5.3.
PUBLISHED: 2021-05-13
An issue was discovered in Prosody before 0.11.9. The undocumented dialback_without_dialback option in mod_dialback enables an experimental feature for server-to-server authentication. It does not correctly authenticate remote server certificates, allowing a remote server to impersonate another serv...
PUBLISHED: 2021-05-13
Prosody before 0.11.9 allows Uncontrolled CPU Consumption via a flood of SSL/TLS renegotiation requests.