Headline
CVE-2021-32642: Injection Attacks Reloaded: Tunnelling Malicious Payloads over DNS
radsecproxy is a generic RADIUS proxy that supports both UDP and TLS (RadSec) RADIUS transports. Missing input validation in radsecproxy’s naptr-eduroam.sh and radsec-dynsrv.sh scripts can lead to configuration injection via crafted radsec peer discovery DNS records. Users are subject to Information disclosure, Denial of Service, Redirection of Radius connection to a non-authenticated server leading to non-authenticated network access. Updated example scripts are available in the master branch and 1.9 release. Note that the scripts are not part of the installation package and are not updated automatically. If you are using the examples, you have to update them manually. The dyndisc scripts work independently of the radsecproxy code. The updated scripts can be used with any version of radsecproxy.
Authors:
Philipp Jeitner, TU Darmstadt; Haya Shulman, Fraunhofer SIT
Abstract:
The traditional design principle for Internet protocols indicates: “Be strict when sending and tolerant when receiving” [RFC1958], and DNS is no exception to this. The transparency of DNS in handling the DNS records, also standardised specifically for DNS [RFC3597], is one of the key features that made it such a popular platform facilitating a constantly increasing number of new applications. An application simply creates a new DNS record and can instantly start distributing it over DNS without requiring any changes to the DNS servers and platforms. Our Internet wide study confirms that more than 1.3M (96% of tested) open DNS resolvers are standard compliant and treat DNS records transparently.
In this work we show that this `transparency’ introduces a severe vulnerability in the Internet: we demonstrate a new method to launch string injection attacks by encoding malicious payloads into DNS records. We show how to weaponise such DNS records to attack popular applications. For instance, we apply string injection to launch a new type of DNS cache poisoning attack, which we evaluated against a population of open resolvers and found 105K to be vulnerable. Such cache poisoning cannot be prevented with common setups of DNSSEC. Our attacks apply to internal as well as to public services, for instance, we reveal that all eduroam services are vulnerable to our injection attacks, allowing us to launch exploits ranging from unauthorised access to eduroam networks to resource starvation. Depending on the application, our attacks cause system crashes, data corruption and leakage, degradation of security, and can introduce remote code execution and arbitrary errors.
In our evaluation of the attacks in the Internet we find that all the standard compliant open DNS resolvers we tested allow our injection attacks against applications and users on their networks.
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**Presentation Video **