A malicious actor who intentionally exploits this lack of effective limitation on the number of fetches performed when processing referrals can, through the use of specially crafted referrals, cause a recursing server to issue a very large number of fetches in an attempt to process the referral. This has at least two potential effects: The performance of the recursing server can potentially be degraded by the additional work required to perform these fetches, and The attacker can exploit this behavior to use the recursing server as a reflector in a reflection attack with a high amplification factor.
A flaw was found in the Bind package. By spoofing the target resolver with responses that have a malformed ECDSA signature, an attacker can trigger a small memory leak, resulting in crashing the program.
A stack exhaustion flaw in control channel code may cause named to terminate unexpectedly
ISC BIND is vulnerable to a denial of service, caused by a logic error in code which checks TSIG validity. A remote attacker could exploit this vulnerability to trigger an assertion failure in tsig.c.
In BIND 9.10.0 -> 9.11.21, 9.12.0 -> 9.16.5, 9.17.0 -> 9.17.3, also affects 9.10.5-S1 -> 9.11.21-S1 of the BIND 9 Supported Preview Edition, An attacker that can reach a vulnerable system with a specially crafted query packet can trigger a crash. To be vulnerable, the system must: be running BIND that was built with "--enable-native-pkcs11" be signing one or more zones with an RSA key be able to receive queries from a possible attacker
An attacker who is able to send and receive messages to an authoritative DNS server and who has knowledge of a valid TSIG key name for the zone and service being targeted may be able to manipulate BIND into accepting an unauthorized dynamic update. A server that relies solely on TSIG or SIG(0) keys with no other address-based ACL protection could be vulnerable to malicious zone content manipulation using this technique.
Workarounds:
The effects of this vulnerability can be mitigated by using Access Control Lists (ACLs) that require both address range validation and use of TSIG authentication in parallel. For information on how to configure this type of compound authentication control, please see:
https://kb.isc.org/article/AA-00723/0/Using-Access-Control-Lists-ACLs-with-both-addresses-and-keys.html.
Administrators who have made use of named.conf option "update-policy local;" should refer to the Administrator Reference Manual (ARM) for details of the automatic update policy that will be established and to assess whether or not this conveys any additional risk to their server. (Note that this option is not enabled by default).
Upstream patch:
https://source.isc.org/cgi-bin/gitweb.cgi?p=bind9.git;a=commitdiff;h=581c1526ab
In BIND 9.8.5 -> 9.8.8, 9.9.3 -> 9.11.29, 9.12.0 -> 9.16.13, and versions BIND 9.9.3-S1 -> 9.11.29-S1 and 9.16.8-S1 -> 9.16.13-S1 of BIND 9 Supported Preview Edition, as well as release versions 9.17.0 -> 9.17.11 of the BIND 9.17 development branch, when a vulnerable version of named receives a malformed IXFR triggering the flaw described above, the named process will terminate due to a failed assertion the next time the transferred secondary zone is refreshed.
A flaw was found in bind. When flooding the target resolver with special queries, an attacker can significantly impair the resolver's performance, effectively denying legitimate clients access to the DNS resolution service.
In BIND 9.3.0 -> 9.11.35, 9.12.0 -> 9.16.21, and versions 9.9.3-S1 -> 9.11.35-S1 and 9.16.8-S1 -> 9.16.21-S1 of BIND Supported Preview Edition, as well as release versions 9.17.0 -> 9.17.18 of the BIND 9.17 development branch, exploitation of broken authoritative servers using a flaw in response processing can cause degradation in BIND resolver performance. The way the lame cache is currently designed makes it possible for its internal data structures to grow almost infinitely, which may cause significant delays in client query processing.
An attacker able to send and receive messages to an authoritative DNS server may be able to circumvent TSIG authentication of AXFR requests via a carefully constructed request packet. A server that relies solely on TSIG keys for protection with no other ACL protection could be manipulated into:
providing an AXFR of a zone to an unauthorized recipient accepting bogus Notify packets
An unauthorized AXFR (full zone transfer) permits an attacker to view the entire contents of a zone. Protection of zone contents is often a commercial or business requirement.
If accepted, a Notify sets the zone refresh interval to 'now'. If there is not already a refresh cycle in progress then named will initiate one by asking for the SOA RR from its list of masters. If there is already a refresh cycle in progress, then named will queue the new refresh request. If there is already a queued refresh request, the new Notify will be discarded. Bogus notifications can't be used to force a zone transfer from a malicious server, but could trigger a high rate of zone refresh cycles.
Workarounds:
The effects of this vulnerability can be mitigated by using Access Control Lists (ACLs) that require both address range validation and use of TSIG authentication in parallel. For information on how to configure this type of compound authentication control, please see:
https://kb.isc.org/article/AA-00723/0/Using-Access-Control-Lists-ACLs-with-both-addresses-and-keys.html.
(Note that this technique will not be effective against bogus Notify packets if an attacker is able to reach the target DNS server whilst using a spoofed sending address).
Upstream patch:
https://source.isc.org/cgi-bin/gitweb.cgi?p=bind9.git;a=commitdiff;h=581c1526ab