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Vulnerability Issues in Implementations of the DNS Protocol
------------------------------------------------------------------------
SUMMARY
The vulnerabilities described in this advisory affect implementations of
the Domain Name System (DNS) protocol. Many vendors include support for
this protocol in their products and may be impacted to varying degrees, if
at all.
DETAILS
Impact:
If exploited, these vulnerabilities could cause a variety of outcomes
including, for example, a Denial-of-Service (DoS) condition. In most
cases, they can expose memory corruption, stack corruption or other types
of fatal error conditions. Some of these conditions may expose the
protocol to typical buffer overflow exploits, allowing arbitrary code to
execute or the system to be modified.
Summary:
During 2002 the Oulu University Secure Programming Group (OUSPG)
discovered a number of implementation specific vulnerabilities in the
Simple Network Management Protocol (SNMP). Further work has been done to
identify implementation specific vulnerabilities in related protocols that
are used in critical infrastructure. The DNS protocol, which is the
primary naming system used on the Internet, was studied as part of this
program of work.
DNS is an Internet service that translates domain names into Internet
Protocol (IP) addresses and vice versa. Because domain names are
alphabetic, they're easier to remember, however the Internet is really
based on IP addresses; therefore every time a domain name is requested, a
DNS service must translate the name into the corresponding IP address.
OUSPG has developed a PROTOS DNS Test Suite for DNS implementations and
employed it to validate their findings against a number of products from
different vendors. NISCC has contacted multiple vendors whose products
support the DNS protocol and provided them with the test tool to allow
them to test their implementations. NISCC believes that most of the
relevant vendors who provide support for the DNS protocol have been
covered by this advisory.
Details:
DNS is a system that stores information associated with domain names in a
distributed database on networks such as the Internet. The domain name
system associates many types of information with domain names, but most
importantly, it provides the IP address associated with the domain name.
It also lists mail exchange servers accepting e-mail for each domain and a
wide variety of other records.
The OUSPG DNS Test Suite covers a limited set of information security and
robustness related implementation errors for the DNS protocol. The factors
behind choosing DNS included:
* DNS is a fundamental infrastructure of the Internet, most Internet
applications are dependent on it.
* DNS implementations are ubiquitous: present in servers, enduser
equipment such as personal computers or mobile phones and in routers and
firewalls. Therefore DNS may be a potential attack vector in a variety of
scenarios against a variety of systems and infrastructure components.
* There are no free, publicly available robustness test suites to
evaluate DNS implementations.
The material contained in the test suite covers basic queries, dynamic
updates, basic responses and zone transfers. However please be aware that
the test material does not cover cache poisoning or address spoofing
vulnerabilities. There are three sets of test materials available with the
tool; these are specifically designed for the following scenarios:
1. The Query Material -> [queries, dynamic DNS updates] -> DNS server
2. The Response Material -> [query replies] -> DNS server
3. The Response Material -> [query replies] -> DNS stub resolver (client)
4. The Zone Transfer Material -> [zone transfers] -> secondary DNS server
The test material simulates hostile input to the DNS implementation by
sending invalid and/or abnormal packets. Therefore by applying the OUSPG
DNS Test Suite to a variety of products, several vulnerabilities can be
revealed that can have varying effects.
Vendor Information:
The following vendors have provided information about how their products
are affected by this vulnerability. Please note that JPCERT/CC have
released a Japanese language advisory for this vulnerability which
contains additional information regarding Japanese vendors. This advisory
is available at <http://jvn.jp/niscc/NISCC-144154/index.html>
http://jvn.jp/niscc/NISCC-144154/index.html
* Cisco Systems, Inc MyDNS
* Delegate pdnsd
* Ethereal Sun
* Hitachi Wind River
* ISC
* Juniper Networks
* Microsoft
Cisco Systems, Inc
Cisco Systems is currently testing its DNS related products. We will
provide updates if warranted at <http://www.cisco.com/go/psirt>
http://www.cisco.com/go/psirt.
Delegate
Vulnerable:
* DeleGate/9.0.5 (DEVELOPMENT) and prior versions
* DeleGate/8.11.5 (STABLE) and prior versions
Not Vulnerable:
* DeleGate/9.0.6 and subsequent versions
* DeleGate/8.11.6 and subsequent versions
DeleGate is an application level gateway (proxy server) which relays
multiple application protocols including HTTP, FTP, SMTP, SOCKS, DNS;
running on Unix and Windows. There have been bugs in its DNS protocol
handling unit where a DNS response message is analyzed.
Due to this problem, DeleGate can suffer a denial-of-service attack. For
some crafted or broken response messages, it reads the message data area
beyond the real size of it, or read it in infinitely recursive function
call. Then the DeleGate process will abort causing segmentation fault or
so accessing non-existent address or non-available memory. DeleGate as DNS
proxy, ICP server and UDP-relay might stop their service receiving such
broken DNS response, since the abortion occurs in the main process which
is not to be restarted automatically by itself. Other DeleGate proxies for
other protocols do not stop servicing but a child process for a session
might abort without returning response message of each application
protocol.
These bugs have been fixed in version 9.0.6 (development version) and
8.11.6 (stable version). The impact for resent versions is not more than
DoS, but upgrading to these versions (or subsequent ones) is recommended.
The impact can be more serious in ancient versions of DeleGate prior to
8.10.3 which also include many other kind of dangers (
<http://www.delegate.org/maillists/delegate-en/2793>
http://www.delegate.org/maillists/delegate-en/2793), so they must be
upgraded anyway.
Ethereal
The Ethereal development team is investigating the reported
vulnerabilities to determine if any versions of Ethereal are affected. We
will provide updated status information in the near future.
Hitachi
Hitachi believe that the AlaxalA Networks AX series, Hitachi
GR2000/GR4000/GS4000/GS3000 and Hitachi HI-UX are NOT vulnerable to this
issue.
ISC
ISC has reviewed a bug that can cause named to terminate abnormally if a
broken TSIG is present in the second or later message of a zone transfer.
However, this is not considered high-risk as the first message must have a
correct TSIG present for the transaction to continue. A fix will be
included in a future BIND release.
Juniper Networks
The OUSPG PROTOS c09-dns-response test tool was run against all Juniper
Networks platforms. JUNOS and ScreenOS were unaffected. Tests against
JUNOSe, found on the E-series routers, did result in an issue with the DNS
client code (ref: KA 23381). The issue was resolved in the following
JUNOSe updates: 5-3-5p0-2, 6-0-3p0-6, 6-0-4, 6-1-3p0-1, 7-0-1p0-7, 7-0-2,
7-1-0p0-1, 7-1-1. Later JUNOSe releases are unaffected.
Microsoft
Microsoft are still testing their products and will provide an update when
more information is available.
MyDNS
MyDNS 1.1.0 has been released which contains a fix for a query-of-death
DoS bug uncovered by the test suite. New versions can be obtained from:
<http://mydns.bboy.net/> http://mydns.bboy.net/
pdnsd
The current maintainer of the pdnsd project, Paul A. Rombouts, has run
tests on pdnsd with the DNS Test Suite mentioned here and discovered one
significant flaw in the pdnsd code, which affects several versions of
pdnsd. A DNS query with an unsupported QTYPE or QCLASS can cause pdnsd to
leak memory. The amount of memory used by pdnsd may thus grow continually
and unbounded and may eventually cause pdnsd to crash or cause the system
to become sluggish and unresponsive. All users of pdnsd are advised to
upgrade to version 1.2.4 or later of pdnsd, which has a fix for this leak
and is available at:
<http://www.phys.uu.nl/~rombouts/pdnsd.html>
http://www.phys.uu.nl/~rombouts/pdnsd.html
Sun
Sun Microsystems is currently investigating the impact of the OUSPG DNS
test suite to Sun's products. If any issues are identified, Sun will
publish Sun Alerts which will include details of the impact and suggested
resolution for those issues.
Wind River
Wind River does not believe that any of the products we provide are
currently vulnerable to the issues described in this Vulnerability Notice.
ADDITIONAL INFORMATION
The information has been provided by <mailto:vulteam@niscc.gov.uk>
Vulnerability Management Team.
The original article can be found at:
<http://www.niscc.gov.uk/niscc/docs/re-20060425-00312.pdf?lang=en>
http://www.niscc.gov.uk/niscc/docs/re-20060425-00312.pdf
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