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authorMounir IDRASSI <mounir.idrassi@idrix.fr>2022-01-27 23:59:55 +0100
committerMounir IDRASSI <mounir.idrassi@idrix.fr>2022-01-30 16:48:49 +0100
commit87efa35c38cf07d174de23c177ee776ee1e10cec (patch)
treefa637da5c6e513731314c3aefcf80649d3ae54b9
parent0d92195c91ec07f2a72d4e4c952bfff672983fa3 (diff)
downloadVeraCrypt-87efa35c38cf07d174de23c177ee776ee1e10cec.tar.gz
VeraCrypt-87efa35c38cf07d174de23c177ee776ee1e10cec.zip
Windows: Enhancement to CVE-2019-19501 fix to using IShellDispatch2::ShellExecuteW if RunAsDesktopUser fails. Also we don't use the fix if UAC is disabled since in this case the Shell Explorer.exe will be elevated anyway so we can't use to reduce elevation.
Diffstat
-rw-r--r--src/Common/Dlgcode.c123
1 files changed, 119 insertions, 4 deletions
diff --git a/src/Common/Dlgcode.c b/src/Common/Dlgcode.c
index 341fcb85..74722af9 100644
--- a/src/Common/Dlgcode.c
+++ b/src/Common/Dlgcode.c
@@ -374,6 +374,12 @@ typedef BOOL (WINAPI *CreateProcessWithTokenWFn)(
__out LPPROCESS_INFORMATION lpProcessInformation
);
+typedef HRESULT (WINAPI *IUnknown_QueryServiceFn)(
+ __in IUnknown* punk,
+ __in REFGUID guidService,
+ __in REFIID riid,
+ __deref_out void ** ppvOut);
+
SetDllDirectoryPtr SetDllDirectoryFn = NULL;
SetSearchPathModePtr SetSearchPathModeFn = NULL;
SetDefaultDllDirectoriesPtr SetDefaultDllDirectoriesFn = NULL;
@@ -390,6 +396,7 @@ SHStrDupWPtr SHStrDupWFn = NULL;
UrlUnescapeWPtr UrlUnescapeWFn = NULL;
ChangeWindowMessageFilterPtr ChangeWindowMessageFilterFn = NULL;
CreateProcessWithTokenWFn CreateProcessWithTokenWPtr = NULL;
+IUnknown_QueryServiceFn IUnknown_QueryServicePtr = NULL;
typedef LONG (WINAPI *WINVERIFYTRUST)(HWND hwnd, GUID *pgActionID, LPVOID pWVTData);
typedef CRYPT_PROVIDER_DATA* (WINAPI *WTHELPERPROVDATAFROMSTATEDATA)(HANDLE hStateData);
@@ -3164,7 +3171,10 @@ void InitApp (HINSTANCE hInstance, wchar_t *lpszCommandLine)
SHDeleteKeyWFn = (SHDeleteKeyWPtr) GetProcAddress (hShlwapiDll, "SHDeleteKeyW");
SHStrDupWFn = (SHStrDupWPtr) GetProcAddress (hShlwapiDll, "SHStrDupW");
UrlUnescapeWFn = (UrlUnescapeWPtr) GetProcAddress(hShlwapiDll, "UrlUnescapeW");
- if (!SHDeleteKeyWFn || !SHStrDupWFn || !UrlUnescapeWFn)
+ IUnknown_QueryServicePtr = (IUnknown_QueryServiceFn) GetProcAddress(hShlwapiDll, "IUnknown_QueryService");
+ if (!IUnknown_QueryServicePtr)
+ IUnknown_QueryServicePtr = (IUnknown_QueryServiceFn) GetProcAddress(hShlwapiDll, MAKEINTRESOURCEA(176));
+ if (!SHDeleteKeyWFn || !SHStrDupWFn || !UrlUnescapeWFn || IUnknown_QueryServicePtr)
AbortProcess ("INIT_DLL");
if (IsOSAtLeast (WIN_VISTA))
@@ -14612,6 +14622,98 @@ BOOL IsElevated()
return bReturn;
}
+// Based on code from:
+// https://github.com/microsoft/Windows-classic-samples/blob/main/Samples/Win7Samples/winui/shell/appplatform/ExecInExplorer/ExecInExplorer.cpp
+HRESULT GetShellViewForDesktop(REFIID riid, void **ppv)
+{
+ *ppv = NULL;
+
+ IShellWindows *psw;
+ HRESULT hr = CoCreateInstance(CLSID_ShellWindows, NULL, CLSCTX_LOCAL_SERVER, IID_PPV_ARGS(&psw));
+ if (SUCCEEDED(hr))
+ {
+ HWND hwnd;
+ IDispatch* pdisp;
+ VARIANT vEmpty = {}; // VT_EMPTY
+ if (S_OK == psw->FindWindowSW(&vEmpty, &vEmpty, SWC_DESKTOP, (long*)&hwnd, SWFO_NEEDDISPATCH, &pdisp))
+ {
+ IShellBrowser *psb;
+ hr = IUnknown_QueryServicePtr(pdisp, SID_STopLevelBrowser, IID_PPV_ARGS(&psb));
+ if (SUCCEEDED(hr))
+ {
+ IShellView *psv;
+ hr = psb->QueryActiveShellView(&psv);
+ if (SUCCEEDED(hr))
+ {
+ hr = psv->QueryInterface(riid, ppv);
+ psv->Release();
+ }
+ psb->Release();
+ }
+ pdisp->Release();
+ }
+ else
+ {
+ hr = E_FAIL;
+ }
+ psw->Release();
+ }
+ return hr;
+}
+
+HRESULT GetShellDispatchFromView(IShellView *psv, REFIID riid, void **ppv)
+{
+ *ppv = NULL;
+
+ IDispatch *pdispBackground;
+ HRESULT hr = psv->GetItemObject(SVGIO_BACKGROUND, IID_PPV_ARGS(&pdispBackground));
+ if (SUCCEEDED(hr))
+ {
+ IShellFolderViewDual *psfvd;
+ hr = pdispBackground->QueryInterface(IID_PPV_ARGS(&psfvd));
+ if (SUCCEEDED(hr))
+ {
+ IDispatch *pdisp;
+ hr = psfvd->get_Application(&pdisp);
+ if (SUCCEEDED(hr))
+ {
+ hr = pdisp->QueryInterface(riid, ppv);
+ pdisp->Release();
+ }
+ psfvd->Release();
+ }
+ pdispBackground->Release();
+ }
+ return hr;
+}
+
+HRESULT ShellExecInExplorerProcess(PCWSTR pszFile)
+{
+ IShellView *psv;
+ CoInitialize(NULL);
+ HRESULT hr = GetShellViewForDesktop(IID_PPV_ARGS(&psv));
+ if (SUCCEEDED(hr))
+ {
+ IShellDispatch2 *psd;
+ hr = GetShellDispatchFromView(psv, IID_PPV_ARGS(&psd));
+ if (SUCCEEDED(hr))
+ {
+ BSTR bstrFile = SysAllocString(pszFile);
+ hr = bstrFile ? S_OK : E_OUTOFMEMORY;
+ if (SUCCEEDED(hr))
+ {
+ VARIANT vtEmpty = {}; // VT_EMPTY
+ hr = psd->ShellExecuteW(bstrFile, vtEmpty, vtEmpty, vtEmpty, vtEmpty);
+ SysFreeString(bstrFile);
+ }
+ psd->Release();
+ }
+ psv->Release();
+ }
+ CoUninitialize();
+ return hr;
+}
+
// This function always loads a URL in a non-privileged mode
// If current process has admin privileges, we execute the command "rundll32 url.dll,FileProtocolHandler URL" as non-elevated
// Use this security mechanism only starting from Windows Vista and only if we can get the window of the Shell's desktop since
@@ -14619,7 +14721,8 @@ BOOL IsElevated()
// then we can't protect the user in such non standard environment
void SafeOpenURL (LPCWSTR szUrl)
{
- if (IsOSAtLeast (WIN_VISTA) && IsAdmin () && IsElevated() && GetShellWindow())
+ BOOL bFallback = TRUE;
+ if (IsOSAtLeast (WIN_VISTA) && IsUacSupported() && IsAdmin () && IsElevated() && GetShellWindow())
{
WCHAR szRunDllPath[TC_MAX_PATH];
WCHAR szUrlDllPath[TC_MAX_PATH];
@@ -14633,11 +14736,23 @@ void SafeOpenURL (LPCWSTR szUrl)
StringCbPrintfW(szUrlDllPath, sizeof(szUrlDllPath), L"%s\\%s", szSystemPath, L"url.dll");
StringCchPrintfW(szCommandLine, 1024, L"%s %s,FileProtocolHandler %s", szRunDllPath, szUrlDllPath, szUrl);
- RunAsDesktopUser (NULL, szCommandLine);
+ if (RunAsDesktopUser (NULL, szCommandLine))
+ {
+ bFallback = FALSE;
+ }
+ else
+ {
+ // fallback to IShellDispatch2::ShellExecuteW
+ if (SUCCEEDED(ShellExecInExplorerProcess(szUrl)))
+ {
+ bFallback = FALSE;
+ }
+ }
delete [] szCommandLine;
}
- else
+
+ if (bFallback)
{
ShellExecuteW (NULL, L"open", szUrl, NULL, NULL, SW_SHOWNORMAL);
}