NetworkManager IPv6 DAD lifetime behavior introduce security risk
Description: When performing IPv6 certification test, two DAD test cases (3.2.5c and d) check the remaining lifetime feature of the IPv6 packets. The Network trace shows that the remaining lifetime becomes infinite when running these test cases. Hence when running in IPv6 environment with Network Manager enabled, there is a risk of packets travelling in network which has valid lifetime always. If these packets are snooped by a hacker he can reply to these packets and they can send legitimate packets which are actually not.
Here is the information for those 2 cases:
v6LC_3_2_4_C - Prefix Lifetime less than the Remaining Lifetime and the Remaining Lifetime is less than 2 hours http://fnet.sourceforge.net/ip6_tests/Self_Test_5-0-0/addr.p2/v6LC_3_2_4_C.html
RA_gt2lt2 - Prefix Lifetime less than 2 hours and the Remaining Lifetime is greater than 2 hours http://fnet.sourceforge.net/ip6_tests/Self_Test_5-0-0/addr.p2/RA_gt2lt2.html
According to https://tools.ietf.org/search/rfc4862, page 19: "The above rules address a specific denial-of-service attack in which a bogus advertisement could contain prefixes with very small Valid Lifetimes. Without the above rules, a single unauthenticated advertisement containing bogus Prefix Information options with short Valid Lifetimes could cause all of a node's addresses to expire prematurely. The above rules ensure that legitimate advertisements (which are sent periodically) will "cancel" the short Valid Lifetimes before they actually take effect."
- 2 test cases pass without NetworkManager.
- Tested with different Linux Desktop Distributions, as long as NetworkManager is running, those DAD test cases fail.