While this isn’t about VoIP, per se, there’s a new version of an Internet-Draft out, draft-ietf-tcpm-icmp-attacks, about how ICMP can be used to attack TCP. The abstract is:
This document discusses the use of the Internet Control Message
Protocol (ICMP) to perform a variety of attacks against the
Transmission Control Protocol (TCP). Additionally, describes a
number of widely implemented modifications to TCP’s handling of ICMP
error messages that help to mitigate these issues.
The document has been around in the IETF space since 2005, but is now moving further down the path toward being issued as an RFC. Seems to be a solid doc for people wanting to understand ICMP attacks.