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.

The RFC 5011 implementation in rdata.c in ISC BIND 9.7.x and 9.8.x before 9.8.5-P2, 9.8.6b1, 9.9.x before 9.9.3-P2, and 9.9.4b1, and DNSco BIND 9.9.3-S1 before 9.9.3-S1-P1 and 9.9.4-S1b1, allows remote attackers to cause a denial of service (assertion failure and named daemon exit) via a query with a malformed RDATA section that is not properly handled during construction of a log message, as exploited in the wild in July 2013.

Last updated 24 July 2024

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.

Under some conditions when using both DNS64 and RPZ to rewrite query responses, query processing can resume in an inconsistent state leading to either an INSIST assertion failure or an attempt to read through a NULL pointer. Affects BIND 9.8.8, 9.9.3-S1 -> 9.9.9-S7, 9.9.3 -> 9.9.9-P5, 9.9.10b1, 9.10.0 -> 9.10.4-P5, 9.10.5b1, 9.11.0 -> 9.11.0-P2, 9.11.1b1.

In BIND 9.0.0 -> 9.11.21, 9.12.0 -> 9.16.5, 9.17.0 -> 9.17.3, also affects 9.9.3-S1 -> 9.11.21-S1 of the BIND 9 Supported Preview Edition, An attacker on the network path for a TSIG-signed request, or operating the server receiving the TSIG-signed request, could send a truncated response to that request, triggering an assertion failure, causing the server to exit. Alternately, an off-path attacker would have to correctly guess when a TSIG-signed request was sent, along with other characteristics of the packet and message, and spoof a truncated response to trigger an assertion failure, causing the server to exit.

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.

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

"managed-keys" is a feature which allows a BIND resolver to automatically maintain the keys used by trust anchors which operators configure for use in DNSSEC validation. Due to an error in the managed-keys feature it is possible for a BIND server which uses managed-keys to exit due to an assertion failure if, during key rollover, a trust anchor's keys are replaced with keys which use an unsupported algorithm. Versions affected: BIND 9.9.0 -> 9.10.8-P1, 9.11.0 -> 9.11.5-P1, 9.12.0 -> 9.12.3-P1, and versions 9.9.3-S1 -> 9.11.5-S3 of BIND 9 Supported Preview Edition. Versions 9.13.0 -> 9.13.6 of the 9.13 development branch are also affected. Versions prior to BIND 9.9.0 have not been evaluated for vulnerability to CVE-2018-5745.