|author||Jason A. Donenfeld <Jason@zx2c4.com>||2020-11-13 03:10:00 +0100|
|committer||Jason A. Donenfeld <Jason@zx2c4.com>||2020-11-22 22:00:32 +0100|
|parent||tunnel: only enable DNS blocking for 0/0 configs (diff)|
manager: allow S-1-5-32-556 users to launch a limited UI
I still have serious security reservations about this, both conceptually -- should users be allowed to do this stuff? -- and pratically -- there are issues with this implementation that need some examination. TODO: - Is that registry key a secure path? Should we double check it? - Are we leaking handles to the unpriv'd process from the manager? Audit this too. - IPC notifications are blocking. Should we move this to a go routine to mitigate DoS potential? - Is GOB deserialization secure? Can an NCO user crash or RCE the manager? Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Diffstat (limited to 'attacksurface.md')
1 files changed, 1 insertions, 0 deletions
diff --git a/attacksurface.md b/attacksurface.md
index 7a4ff7d1..553806cf 100644
@@ -31,6 +31,7 @@ The manager service is a userspace service running as Local System, responsible
- It listens for service changes in tunnel services according to the string prefix "WireGuardTunnel$".
- It manages DPAPI-encrypted configuration files in `C:\Program Files\WireGuard\Data`, which is created with `O:SYG:SYD:PAI(A;OICI;FA;;;SY)(A;OICI;FR;;;BA)`, and makes some effort to enforce good configuration filenames.
- It uses `WTSEnumerateSessions` and `WTSSESSION_NOTIFICATION` to walk through each available session. It then uses `WTSQueryUserToken`, and then calls `GetTokenInformation(TokenGroups)` on it. If one of the returned group's SIDs matches `IsWellKnownSid(WinBuiltinAdministratorsSid)`, and has attributes of either `SE_GROUP_ENABLED` or `SE_GROUP_USE_FOR_DENY_ONLY` and calling `GetTokenInformation(TokenElevation)` on it or its `TokenLinkedToken` indicates that either is elevated, then it spawns the UI process as that the elevated user token, passing it three unnamed pipe handles for IPC and the log mapping handle, as described above.
+ - In the event that the administrator has set `HKLM\Software\WireGuard\LimitedOperatorUI` to 1, sessions are started for users that are a member of group S-1-5-32-556, with a more limited IPC interface, in which these non-admin users are denied private keys and tunnel editing rights. (This means users can potentially DoS the IPC server by draining notifications too slowly, or exhausting memory of the manager by spawning too many watcher go routines, or by sending garbage data that Go's `gob` decoder isn't expecting.)