From a14884ebf4657498aedceaac4b13890438849c94 Mon Sep 17 00:00:00 2001 From: Jonas Bushart Date: Sat, 3 Jun 2023 21:40:41 +0200 Subject: [PATCH] Vulnerability in trust-dns and trust-dns-server (#1703) An attacker can form packet loops between vulnerable instances leading to a denial-of-service for both network and CPU resources. --- crates/trust-dns-server/RUSTSEC-0000-0000.md | 31 ++++++++++++++++++++ 1 file changed, 31 insertions(+) create mode 100644 crates/trust-dns-server/RUSTSEC-0000-0000.md diff --git a/crates/trust-dns-server/RUSTSEC-0000-0000.md b/crates/trust-dns-server/RUSTSEC-0000-0000.md new file mode 100644 index 0000000..4a9455c --- /dev/null +++ b/crates/trust-dns-server/RUSTSEC-0000-0000.md @@ -0,0 +1,31 @@ +```toml +[advisory] +id = "RUSTSEC-0000-0000" +package = "trust-dns-server" +date = "2023-06-01" +url = "https://github.com/bluejekyll/trust-dns/pull/1952" +categories = ["denial-of-service"] +keywords = ["packet loop"] + +[versions] +patched = ["^0.22.1", ">=0.23.0-alpha.3"] +``` + +# Remote Attackers can cause Denial-of-Service (packet loops) with crafted DNS packets + +trust-dns and trust-dns-server are vulnerable to remotely triggered denial-of-service attacks, consuming both network and CPU resources. +DNS messages with the QR=1 bit set are responded to with a `FormErr` response. +This allows creating a traffic loop, in which these `FormErr` responses are sent nonstop between vulnerable servers. + +There are two scenarios how this can be exploited: 1) Create a loop between two instances of trust-dns, consuming network resources, or 2) consuming the CPU of a single instance. + +With two instances *A* and *B* an attacker sends a DNS query with a spoofed source IP address to *A*. +*A* replies with a `FormErr` to *B*. +Now both servers with ping-pong the message back and forth until by chance the packet is dropped in the network. +Multiple spoofed packets can be sent by the attacker, increasing resource consumption. + +A single server can get locked up replying to itself. +Same setup as above, but now *A* sends the reply to itself. +The packet is sent out as fast as the CPU and network stack manage. +This locks up a CPU core. +Multiple packets from the attacker consume multiple CPU cores.