#596 Dialback key generation in 0.9 allows servers to impersonate to suffices
Reporter
Thijs Alkemade
Owner
MattJ
Created
Updated
Stars
★ (1)
Tags
Type-Defect
Status-Fixed
Priority-High
Security
Thijs Alkemade
on
1. example.lit connects to foo.example.lit claiming to be prosody.lit on the initial stream header
2. foo.example.lit offers dialback and stream ID "abc"
3. example.lit triggers a connection from prosody.lit to example.lit
4. example.lit offers dialback and stream ID "abcfoo."
5. prosody.lit generates SHA256("abcfoo.example.litprosody.litb97b59cd-f9f8-4d5e-b43f-96107303c30e") as dialback key: https://hg.prosody.im/0.9/file/0386ccf20ac7/plugins/mod_dialback.lua#l22
6. example.lit forwards this dialback key to foo.example.lit
7. foo.example.lit connects back to prosody.lit
8. prosody.lit says the key is valid
9. example.lit is now authorized to send messages to foo.example.lit pretending to be from prosody.lit
The target domain doesn't strictly need to subdomain, just a suffix: alice.example.lit could be impersonated by lice.example.lit. This is pretty common for things like no-ip.org.
The problem is the lack of separation of the different fields in generate_dialback(). XEP-0185 fixes this by requiring spaces between the different parts. https://hg.prosody.im/0.10/rev/dd8265ca9327 implemented that, but only for 0.10+.
1. example.lit connects to foo.example.lit claiming to be prosody.lit on the initial stream header 2. foo.example.lit offers dialback and stream ID "abc" 3. example.lit triggers a connection from prosody.lit to example.lit 4. example.lit offers dialback and stream ID "abcfoo." 5. prosody.lit generates SHA256("abcfoo.example.litprosody.litb97b59cd-f9f8-4d5e-b43f-96107303c30e") as dialback key: https://hg.prosody.im/0.9/file/0386ccf20ac7/plugins/mod_dialback.lua#l22 6. example.lit forwards this dialback key to foo.example.lit 7. foo.example.lit connects back to prosody.lit 8. prosody.lit says the key is valid 9. example.lit is now authorized to send messages to foo.example.lit pretending to be from prosody.lit The target domain doesn't strictly need to subdomain, just a suffix: alice.example.lit could be impersonated by lice.example.lit. This is pretty common for things like no-ip.org. The problem is the lack of separation of the different fields in generate_dialback(). XEP-0185 fixes this by requiring spaces between the different parts. https://hg.prosody.im/0.10/rev/dd8265ca9327 implemented that, but only for 0.10+.
Fixed in 5c6e78dc1864.
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