Bug 125093 - Windows: Honor Mark-of-the-Web (MotW) ("Zone.Identifier" stream), and open files from restricted zones in read-only mode
Summary: Windows: Honor Mark-of-the-Web (MotW) ("Zone.Identifier" stream), and open fi...
Status: NEW
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: LibreOffice (show other bugs)
(earliest affected)
Hardware: All All
: medium enhancement
Assignee: Not Assigned
URL: https://textslashplain.com/2020/01/30...
Whiteboard: target:7.6.0
Depends on:
Blocks: Privacy
  Show dependency treegraph
Reported: 2019-05-03 05:59 UTC by Mike Kaganski
Modified: 2023-12-06 05:28 UTC (History)
6 users (show)

See Also:
Crash report or crash signature:


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Description Mike Kaganski 2019-05-03 05:59:14 UTC
There's a "Zone.Identifier" alternate file stream [1], written to downloaded files by all browsers to indicate that the files come from untrusted location, and their treatment should be restricted until they are unlocked [2].

The proposal is to honor this data, and offer to open such files in read-only mode, with macros disabled.

[1] https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-fscc/6e3f7352-d11c-4d76-8c39-2516a9df36e8
[2] http://woshub.com/how-windows-determines-that-the-file-has-been-downloaded-from-the-internet/
Comment 1 Buovjaga 2019-08-17 15:57:22 UTC
I believe you, so I set to NEW
Comment 2 Mike Kaganski 2022-01-08 09:47:18 UTC
IMO, the proper place to put this check would be SfxMedium::IsReadOnly (sfx2/source/doc/docfile.cxx), which is called from SfxObjectShell::IsReadOnlyMedium, which in turn is called from SfxObjectShell::DoLoad. I am unsure wrt implementation; maybe we could use ucbhelper::Content::getPropertyValue, passing some new property name like "SecurityZone" or similar, which would on Windows check the stream documented in references listed in comment 0. Stephan: what do you think?
Comment 3 Stephan Bergmann 2022-01-10 07:27:08 UTC
(In reply to Mike Kaganski from comment #2)
> Stephan: what do you think?

Sounds like a plan, but I don't think I have any useful input.  (Whenever I tried to modify the relevant sfx2 code, it looked like a complete mess to me.  And instead of doing the alternate file stream access via UCB, it might also be plausible to do it directly via whatever Windows-only API in sfx2.)
Comment 4 Mike Kaganski 2022-07-14 08:20:56 UTC
FTR: IInternetSecurityManager handles everything required itself: mapping both the location, the Zone.Identifier stream, and even something called "Mark of the Web", itself. So this function would suffice:

static bool IsRestrictedZone(const OUString& sURL)
#ifdef _WIN32
    if (sURL.isEmpty())
        return false;

        DWORD dwZone;
        sal::systools::COMReference<IInternetSecurityManager> ism(CLSID_InternetSecurityManager);
            ism->MapUrlToZone(o3tl::toW(sURL.getStr()), &dwZone, MUTZ_DONT_UNESCAPE),
            "IInternetSecurityManager::MapUrlToZone failed");
        if (dwZone >= URLZONE_INTERNET)
            return true;
    catch (const sal::systools::ComError&)
        // No problem; assume no zone information == no restriction
    return false;

Using it as another condition to SetReadOnlyUI() in SfxObjectShell::DoLoad would do - except the infobar would not hint why the read-only happened.

So I put it all here, because I don't have energy to do deeper modifications in UI myself. Also there seem to be no similar requests - so maybe it's just me, and not needed to users actually. So - WF; but if someone decides to implement, please reopen and do it.
Comment 6 Commit Notification 2022-12-30 04:25:11 UTC
Vasily Melenchuk committed a patch related to this issue.
It has been pushed to "master":


Related: tdf#125093 Check Windows Security Zones for macros

It will be available in 7.6.0.

The patch should be included in the daily builds available at
https://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More
information about daily builds can be found at:

Affected users are encouraged to test the fix and report feedback.
Comment 8 Samuel Mehrbrodt (allotropia) 2023-01-26 08:37:42 UTC
How should this work in combination with the existing macro security levels?
Currently when Macro Security is "Low", the Windows Security zone is ignored and macros are always enabled.
When Macro Security is "High" or "Very high", the Windows Security zone is also ignored.
It is only evaluated when Macro security is set to "Medium".

Somehow the security zones need to be integrated with the existing Macro security levels.
Comment 9 Mike Kaganski 2023-01-26 08:43:04 UTC
Note that the macro security is somewhat orthogonal to (or maybe just part of) the original proposal here: the read-only mode of the file open is not the same as blocking macros. I suppose that the read-only state needs not to be bound to the macro security.