Fix potential security issue

[oberrich]

See Chromium's implementation as well as crbug/441834.

[DoumanAsh]

Sorry, I understand there is bug in chromium, but is there reference to MS documentation indicating that CloseClipboard() has such security problem?

[oberrich]

Sorry, I understand there is bug in chromium, but is there reference to MS documentation indicating that CloseClipboard() has such security problem?

https://www.exploit-db.com/exploits/38199 (This also contains a PoC)
https://learn.microsoft.com/en-us/security-updates/securitybulletins/2015/ms15-097
https://www.cve.org/CVERecord?id=CVE-2015-2511 (I guess)

[DoumanAsh]

Thank you, I will read it later this evening to confirm impact

[oberrich]

Thank you, I will read it later this evening to confirm impact

This should only affect users who use clipboard-win from a system process. Rough tl;dr as I understand it: The windows kernel potentially leaks a token when you close clipboard from system process without first impersonating the system's anonymous logon token (ImpersonateAnonymousToken). Leaked token can be obtained via NtUserGetClipboardAccessToken syscall.

[DoumanAsh]

From my understanding this is problem only for any elevated processes actually.
I wonder if this should be checked only for these?

I could implement one time check using CheckTokenMembership whether process is running with admin privileges
Although I wonder if it is worth to do

[DoumanAsh]

@oberrich I made small correction to PR fd26c59

Note that _ drops object immediately so if you want to RevertSelf correctly you should have actual binding

[oberrich]

I could implement one time check using CheckTokenMembership whether process is running with admin privileges Although I wonder if it is worth to do

Highly doubtful, performance difference is probably negligible and this would be premature optimization. This operation is safe to be called unconditionally as Chromium implements this identically in C++.

Good catch with the drop! I’m new to rust and forgot about that 😅

[DoumanAsh]

Anyway thanks for PR

I released 5.3.1 which includes this PR