Уязвимости nsd

Stack overwrite from specially formatted TXT-DATA RDATA field

Tokens of text in RDATA (of for example TXT records) under 32 bytes are not checked to stay within the space reserved for the RDATA allowing for arbitrary sized out of bound stack writes, including an overwrite of a callback function pointer which is called directly after parse. Zone files which are written out by NSD itself, such for zones for which the NSD instance is secondary, will not be formatted like this. The zone file must be fed to NSD directly, (but it could come, for example, from an operator controlled provisioning system).

Stack overwrite from a specially crafted and formatted HIP RR

A HIP resource record that fills the RDATA near or at is limit, and has another dname RDATA field (a HIP Rendezvous server) can overwrite the stack with up to 191 bytes of attacker controlled data. Zone files which are written out by NSD itself, such as for zones for which the NSD instance is secondary, will not be formatted like this. The zone file must be fed to NSD directly, (but it could come, for example, from an operator controlled provisioning system).

Stack overwrite from a specially crafted and formatted SVCB or HTTPS RR

When a SVCB or HTTPS RR has filled the wire format RDATA up to the brim, another ECH parameter may overwrite the stack, and once beyond the limit, the base64 decoder can write attacker controlled data of unlimited size. Zone files which are written out by NSD itself, such as for zones for which the NSD instance is secondary, will not be formatted like this. The zone file must be fed to NSD directly, (but it could come, for example, from an operator controlled provisioning system).

Stack overwrite from specially formatted base64 RDATA field

When base64 data is split up in pieces, of 3 character or less, tokens were incorrectly calculated to produce 0 bytes. This enables attackers to overwrite the stack with up to 64K of attacker controlled data. Zone files which are written out by NSD itself, such as for zones for which the NSD instance is secondary, will not be formatted like this. The zone file must be fed to NSD directly, (but it could come, for example, from an operator controlled provisioning system).

Bypass of BLOCKED ACL items on proxy protocol port over TCP or TLS

The BLOCKED access control list items that are evaluated to deny access on the the proxy protocol port can be bypassed completely when connecting over TCP or TLS and sending the query twice on connection that is kept open.

Remote UDP DoS by sending multiple DNS Cookie options

Any remote client can crash a (debugging/non-release build type) NSD serve child by sending it a special crafted message with a specially tuned number of DNS Cookie options (17 when UDP payload size is 512). By continuously crashing the serve childs, the remote client can severely hamper or, when positioned sufficiently close, deny all DNS service.

Remote TCP DoS by throttling the TCP receive window

Any remote client can crash a NSD serve child, by throttling the TCP receive window after a TCP query. By continuously crashing the serve childs, the remote client can denial all TCP service to this NSD instance.

Wrong interpretation of ACL ranges

When ranges are used for access control (i.e. of the form 1.2.3.4-1.2.3.25), because NSD wrongly compares the IP address with the range on little endian systems, IPs that were meant to be allowed may be denied, and, IPs that were meant to be denied access could be allowed. An IPv4 address is compared with IPv4 ranges as unsigned 32 bit numbers directly with the endianness of the host, but the values to compare are in network byte order (big-endian). With IPv6 addresses the comparison is done in 4 times a unsigned 32 bit number comparison, again with the endianness of the host where all values are actually in network bye order.

Bypass of client certificate verification with transfer over TLS

When a provide-xfr is given with a tls-auth-name, a secondary requesting a transfer should provide a client certificate with that name. However, no client certificate is needed when the request comes in over TLS over the regular tls-port (and not the tls-auth-port) or over over TCP over the regular port, when the other conditions of the provide-xfr rule match.

Local symlink attack in Unbound and NSD

NLnet Labs Unbound, up to and including version 1.12.0, and NLnet Labs NSD, up to and including version 4.3.3, contain a local vulnerability that would allow for a local symlink attack. When writing the PID file, Unbound and NSD create the file if it is not there, or open an existing file for writing. In case the file was already present, they would follow symlinks if the file happened to be a symlink instead of a regular file. An additional chown of the file would then take place after it was written, making the user Unbound/NSD is supposed to run as the new owner of the file. If an attacker has local access to the user Unbound/NSD runs as,

• Обновитесь до 4.3.4-1

CVE-2019-13207

nsd-checkzone in NLnet Labs NSD 4.2.0 has a Stack-based Buffer Overflow in the dname_concatenate() function in dname.c.

• Обновитесь до 4.2.4-1

CVE-2016-6173

NSD before 4.1.11 allows remote DNS master servers to cause a denial of service (/tmp disk consumption and slave server crash) via a zone transfer with unlimited data.

• Обновитесь до 4.1.11-1

CVE-2009-1755

Off-by-one error in the packet_read_query_section function in packet.c in nsd 3.2.1, and process_query_section in query.c in nsd 2.3.7, allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via unspecified vectors that trigger a buffer overflow.

• Обновитесь до 2.3.7-3