Strange IPSEC traffic

Mailman List Mirror (Read Only)
1

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

2

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

3

A new attack was published against SSH and the paper authors are theorizing that the attack is possible against IPSEC due to flaws in the CPU that are exploitable via brute force.

4

Hi,

A new attack was published against SSH and the paper authors are theorizing that
the attack is possible against IPSEC due to flaws in the CPU that are
exploitable via brute force.

For those interested, here is the paper: https://eprint.iacr.org/2023/1711.pdf

It's written for SSH, but the authors theorize it will work for IPSec as well.

Thanks,

Sabri

5

Attackers will sometimes use synthetic ESP, AH, GRE, or other protocols in DDoS attacks, because organizations often only think about TCP/UDP/ICMP in terms of ACLs, DDoS defense mechanisms, etc.

6

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

I’ve seen traffic like this for the better part of at least the last 7 years, fairly consistently.

It’s definitely not something new.

7

* Shawn L [Mon 13 Nov 2023, 18:12 CET]:

Is anyone else seeing a lot of 'strange' IPSEC traffic?

This mail server running FreeBSD did: (timestamps in CET, UTC+1)

Nov 10 00:58:55 mailserver kernel: ipsec_common_input: no key association found for SA 77.174.253.13/77b40000/50
Nov 10 01:26:09 mailserver kernel: ipsec_common_input: no key association found for SA 77.174.253.13/03e80000/50
Nov 11 10:15:22 mailserver kernel: ipsec_common_input: no key association found for SA 77.174.253.13/62861b0e/50
Nov 11 14:35:34 mailserver kernel: ipsec_common_input: no key association found for SA 77.174.253.13/048b828c/50
Nov 13 20:00:53 mailserver kernel: ipsec_common_input: no key association found for SA 77.174.253.13/a5ff0000/50

I don't remember ever seeing these log messages before.

  -- Niels.