SSL Splicing uses IP address instead of SNI

[Dractyl]

Hi everyone,

I've got a curious problem regarding SSL Splicing on Squid (no SquidGuard) on 2.5.2.

When I try to access any SSL web page (for which I have an entry in my whitelist), I get an error page from Squid showing me that I am not allowed to access the resolved IP address of that server.

This matches what is in the "Real Time" tab:

04.08.2021 15:22:19 	[ADDRESS] 	NONE/403 	https://www.microsoft.com/ 	- 	-
04.08.2021 15:22:19 	[ADDRESS] 	TCP_DENIED/200 	23.44.161.156:443 	- 	-

I also turned on some more extensive logging (debug_options ALL,1 83,3 28,3 78,3 33,3 35,3) and noticed that there was header data in there, which I should not be able to get on a splice.

My config works fine if I manually set the client's proxy. Transparent HTTP works as well.

Here is the generated config:

Spoiler

http_port [ADDRESS]:3128 ssl-bump generate-host-certificates=on dynamic_cert_mem_cache_size=10MB cert=/usr/local/etc/squid/serverkey.pem cafile=/usr/local/share/certs/ca-root-nss.crt capath=/usr/local/share/certs/ cipher=EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EECDH+aRSA+RC4:EECDH:EDH+aRSA:!RC4:!aNULL:!eNULL:!LOW:!3DES:!SHA1:!MD5:!EXP:!PSK:!SRP:!DSS tls-dh=prime256v1:/etc/dh-parameters.4096 options=NO_SSLv3,NO_TLSv1,SINGLE_DH_USE,SINGLE_ECDH_USE

http_port 127.0.0.1:3128 intercept ssl-bump generate-host-certificates=on dynamic_cert_mem_cache_size=10MB cert=/usr/local/etc/squid/serverkey.pem cafile=/usr/local/share/certs/ca-root-nss.crt capath=/usr/local/share/certs/ cipher=EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EECDH+aRSA+RC4:EECDH:EDH+aRSA:!RC4:!aNULL:!eNULL:!LOW:!3DES:!SHA1:!MD5:!EXP:!PSK:!SRP:!DSS tls-dh=prime256v1:/etc/dh-parameters.4096 options=NO_SSLv3,NO_TLSv1,SINGLE_DH_USE,SINGLE_ECDH_USE

https_port 127.0.0.1:3129 intercept ssl-bump generate-host-certificates=on dynamic_cert_mem_cache_size=10MB cert=/usr/local/etc/squid/serverkey.pem cafile=/usr/local/share/certs/ca-root-nss.crt capath=/usr/local/share/certs/ cipher=EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EECDH+aRSA+RC4:EECDH:EDH+aRSA:!RC4:!aNULL:!eNULL:!LOW:!3DES:!SHA1:!MD5:!EXP:!PSK:!SRP:!DSS tls-dh=prime256v1:/etc/dh-parameters.4096 options=NO_SSLv3,NO_TLSv1,SINGLE_DH_USE,SINGLE_ECDH_USE

icp_port 0
digest_generation off
dns_v4_first on
pid_filename /var/run/squid/squid.pid
cache_effective_user squid
cache_effective_group proxy
error_default_language en
icon_directory /usr/local/etc/squid/icons
visible_hostname [HOSTNAME]
cache_mgr [EMAIL]
access_log /var/squid/logs/access.log
cache_log /var/squid/logs/cache.log
cache_store_log none
netdb_filename /var/squid/logs/netdb.state
pinger_enable on
pinger_program /usr/local/libexec/squid/pinger
sslcrtd_program /usr/local/libexec/squid/security_file_certgen -s /var/squid/lib/ssl_db -M 4MB -b 2048
tls_outgoing_options cafile=/usr/local/share/certs/ca-root-nss.crt
tls_outgoing_options capath=/usr/local/share/certs/
tls_outgoing_options options=NO_SSLv3,NO_TLSv1,SINGLE_DH_USE,SINGLE_ECDH_USE
tls_outgoing_options cipher=EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EECDH+aRSA+RC4:EECDH:EDH+aRSA:!RC4:!aNULL:!eNULL:!LOW:!3DES:!SHA1:!MD5:!EXP:!PSK:!SRP:!DSS
sslcrtd_children 5

logfile_rotate 0
debug_options rotate=0
shutdown_lifetime 3 seconds
forwarded_for off
via off
httpd_suppress_version_string on
uri_whitespace strip


cache_mem 64 MB
maximum_object_size_in_memory 256 KB
memory_replacement_policy heap GDSF
cache_replacement_policy heap LFUDA
minimum_object_size 0 KB
maximum_object_size 4 MB
cache_dir ufs /var/squid/cache 100 16 256
offline_mode off
cache_swap_low 90
cache_swap_high 95
cache allow all
# Add any of your own refresh_pattern entries above these.
refresh_pattern ^ftp:    1440  20%  10080
refresh_pattern ^gopher:  1440  0%  1440
refresh_pattern -i (/cgi-bin/|\?) 0  0%  0
refresh_pattern .    0  20%  4320


#Remote proxies


# Setup some default acls
# ACLs all, manager, localhost, and to_localhost are predefined.
acl allsrc src all
acl safeports port 21 70 80 210 280 443 488 563 591 631 777 901  3128 3129 1025-65535 
acl sslports port 443 563  

acl purge method PURGE
acl connect method CONNECT

# Define protocols used for redirects
acl HTTP proto HTTP
acl HTTPS proto HTTPS

# SslBump Peek and Splice
# http://wiki.squid-cache.org/Features/SslPeekAndSplice
# http://wiki.squid-cache.org/ConfigExamples/Intercept/SslBumpExplicit
# Match against the current step during ssl_bump evaluation [fast]
# Never matches and should not be used outside the ssl_bump context.
#
# At each SslBump step, Squid evaluates ssl_bump directives to find
# the next bumping action (e.g., peek or splice). Valid SslBump step
# values and the corresponding ssl_bump evaluation moments are:
#   SslBump1: After getting TCP-level and HTTP CONNECT info.
#   SslBump2: After getting TLS Client Hello info.
#   SslBump3: After getting TLS Server Hello info.
# These ACLs exist even when 'SSL/MITM Mode' is set to 'Custom' so that
# they can be used there for custom configuration.
acl step1 at_step SslBump1
acl step2 at_step SslBump2
acl step3 at_step SslBump3
acl whitelist dstdom_regex -i "/var/squid/acl/whitelist.acl"
http_access allow manager localhost

http_access deny manager
http_access allow purge localhost
http_access deny purge
http_access deny !safeports
http_access deny CONNECT !sslports

# Always allow localhost connections
http_access allow localhost

request_body_max_size 0 KB
delay_pools 1
delay_class 1 2
delay_parameters 1 -1/-1 -1/-1
delay_initial_bucket_level 100
delay_access 1 allow allsrc

# Reverse Proxy settings


# Custom options before auth

# Always allow access to whitelist domains
http_access allow whitelist
# Set YouTube safesearch restriction
acl youtubedst dstdomain -n www.youtube.com m.youtube.com youtubei.googleapis.com youtube.googleapis.com www.youtube-nocookie.com
request_header_access YouTube-Restrict deny all
request_header_add YouTube-Restrict none youtubedst
ssl_bump peek step1
ssl_bump splice all
# Setup allowed ACLs
# Default block all to be sure
http_access deny allsrc

So my basic concerns are:

• Shouldn't this be using the SNI to check the white list?
• Why is there an asterisk at the end of that URL?
• Why am I seeing headers in the logs given that I am using "Splice All"? During a splice the system should neither be reading nor creating headers; it's a straight TCP pass thru.

Does this look familiar to anyone?

Thanks!