So ... more digging, with the result. It seems that although I ran one process normal and one "As Administrator", I had UAC off. Turning UAC to medium allowed me to see different results. Basically, it all boils down to integrity levels, which are 5.
Browsers, for example, run at Low Level (1), while services (System user) run at System Level (4). Everything is very well explained in Windows Integrity Mechanism Design . When UAC is enabled, processes are created with Medium level (SID S-1-16-8192 AKA 0x2000 is added) while when "Run as Administrator", the process is created with High Level (SID S-1-16-12288 aka 0x3000).
So the correct ACCESS_TOKEN for a normal user (Medium Integrity level) is:
0:000:x86> !token
Thread is not impersonating. Using process token...
TS Session ID: 0x1
User: S-1-5-21-1542574918-171588570-488469355-1000
Groups:
00 S-1-5-21-1542574918-171588570-488469355-513
Attributes - Mandatory Default Enabled
01 S-1-1-0
Attributes - Mandatory Default Enabled
02 S-1-5-32-544
Attributes - DenyOnly
03 S-1-5-32-545
Attributes - Mandatory Default Enabled
04 S-1-5-4
Attributes - Mandatory Default Enabled
05 S-1-2-1
Attributes - Mandatory Default Enabled
06 S-1-5-11
Attributes - Mandatory Default Enabled
07 S-1-5-15
Attributes - Mandatory Default Enabled
08 S-1-5-5-0-1908477
Attributes - Mandatory Default Enabled LogonId
09 S-1-2-0
Attributes - Mandatory Default Enabled
10 S-1-5-64-10
Attributes - Mandatory Default Enabled
11 S-1-16-8192
Attributes - GroupIntegrity GroupIntegrityEnabled
Primary Group: LocadDumpSid failed to dump Sid at addr 000000000266b458, 0xC0000078; try own SID dump.
s-1-0x515000000
Privs:
00 0x000000013 SeShutdownPrivilege Attributes -
01 0x000000017 SeChangeNotifyPrivilege Attributes - Enabled Default
02 0x000000019 SeUndockPrivilege Attributes -
03 0x000000021 SeIncreaseWorkingSetPrivilege Attributes -
04 0x000000022 SeTimeZonePrivilege Attributes -
Auth ID: 0:1d1f65
Impersonation Level: Anonymous
TokenType: Primary
Is restricted token: no.
Now, the differences are as follows:
S-1-5-32-544
Attributes - Mandatory Default Enabled Owner
for "As Admin", while
S-1-5-32-544
Attributes - DenyOnly
for non-admin.
Note that S-1-5-32-544 is BUILTIN\Administrators. Also, there are fewer privileges, and the most important thing to notice:
admin:
S-1-16-12288
Attributes - GroupIntegrity GroupIntegrityEnabled
while for non-admin:
S-1-16-8192
Attributes - GroupIntegrity GroupIntegrityEnabled
I hope this helps.
Further reading: http://www.blackfishsoftware.com/blog/don/creating_processes_sessions_integrity_levels