Описание
Netty: DNS Cache Poisoning due to Predictable PRNG and Default Static Source Port
Summary
Netty's DNS resolver uses a predictable PRNG for generating DNS transaction IDs and defaults to a static UDP source port. This combination reduces the entropy of DNS queries, enabling DNS Cache Poisoning (Kaminsky attack).
Details
Two factors contribute to this vulnerability in io.netty.resolver.dns:
- Predictable Query IDs:
DnsQueryIdSpacemanages 16-bit transaction IDs in buckets of 16,384 IDs. It initializes only the first bucket. When an ID is returned, it is pushed back into the bucket at a random index generated by java.util.concurrent.ThreadLocalRandom:
Because ThreadLocalRandom is a predictable LCG and the resolver operates within a single bucket, the sequence of IDs is predictable once the PRNG state is mathematically recovered.
- Default Static Source Port:
DnsNameResolverBuilderdefaults to achannelStrategyofChannelPerResolver. This binds the DatagramChannel once, resulting in a static source port for all subsequent queries.
Combined, a static source port and predictable transaction IDs reduces the entropy required to secure DNS resolution against spoofing.
Impact
DNS Cache Poisoning. Downstream applications using the default Netty DNS resolver may connect to malicious IPs, leading to traffic interception or MitM attacks.
Пакеты
io.netty:netty-resolver-dns
>= 4.2.0.Final, <= 4.2.14.Final
4.2.15.Final
io.netty:netty-resolver-dns
<= 4.1.134.Final
4.1.135.Final
Связанные уязвимости
Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, Netty's DNS resolver uses a predictable PRNG for generating DNS transaction IDs and defaults to a static UDP source port. This combination reduces the entropy of DNS queries, enabling DNS Cache Poisoning (Kaminsky attack). Versions 4.1.135.Final and 4.2.15.Final patch the issue.
Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, Netty's DNS resolver uses a predictable PRNG for generating DNS transaction IDs and defaults to a static UDP source port. This combination reduces the entropy of DNS queries, enabling DNS Cache Poisoning (Kaminsky attack). Versions 4.1.135.Final and 4.2.15.Final patch the issue.
Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, Netty's DNS resolver uses a predictable PRNG for generating DNS transaction IDs and defaults to a static UDP source port. This combination reduces the entropy of DNS queries, enabling DNS Cache Poisoning (Kaminsky attack). Versions 4.1.135.Final and 4.2.15.Final patch the issue.
Netty is a network application framework for development of protocol s ...
