On 11/13/23 19:10, Shawn L via NANOG wrote:

Is anyone else seeing a lot of 'strange' IPSEC traffic? We started seeing logs of IPSEC with invalid spi on Friday. We're seeing it on pretty much all of our PE routers, none of which are setup to do anything VPN related. Most are just routing local customer traffic.

decaps: rec'd IPSEC packet has invalid spi for destaddr=X.X.X.X, prot=50, spi=0x9D2D0000(2636972032), srcaddr=211.112.195.167, input interface=TenGigabitEthernet0/0/11

decaps: rec'd IPSEC packet has invalid spi for destaddr=Y.Y.Y.Y, prot=50, spi=0x14690000(342425600), srcaddr=74.116.56.244, input interface=TenGigabitEthernet0/0/5

The destination address is always one of our customer's ip addresses. The source seems to be all over the place, mostly Russia, Korea, China or south east asia. It's not really impacting anything at the moment, just rather annoying.

Thanks

Shawn

Hi Shawn,

we saw a lot of syslog messages like these and the targets are cisco devices, some of witch, according to the data sheets, are not even capable of ipsec.

Cisco is punting some ESP traffic to control plane on ios and ios-xe devices, regardless of the configuration.

Last week somebody on the internet started a campaign to scan and perhaps to exploit some zero day ipsec vulnerabilities.

This is the list of ip addresses we saw: https://pastebin.com/vrLRai9Q

-- 
Best regards,
Adrian Minta