SumatraPDF 3.1.2 DLL Hijacking

`Hi @ll,  
  
the executable installer [deg] and the "portable" version  
of SumatraPDF 3.1.2 (available from  
<https://www.sumatrapdfreader.org/download-free-pdf-viewer.html>)  
are vulnerable to DLL hijacking [']:  
  
The executable installers SumatraPDF-3.1.2-install.exe and  
SumatraPDF-3.1.2-64-install.exe load and execute (tested on  
a fully patched Windows 7 SP1) at least Version.dll, OLEACC.dll,  
CryptBase.dll, NTMARTA.dll, LinkInfo.dll, NTSHRUI.dll,  
NetUtils.dll, SrvCli.dll, CSCAPI.dll, SLC.dll, PropSys.dll from  
the directory they are started from (the "application directory")  
instead Windows "system directory", resulting in arbitrary code  
execution.  
  
For software downloaded with a web browser the "application  
directory" is typically the user's "Downloads" directory: see  
<http://seclists.org/fulldisclosure/2015/Nov/101> and  
<http://seclists.org/fulldisclosure/2015/Dec/86> plus  
<https://insights.sei.cmu.edu/cert/2008/09/carpet-bombing-and-directory-poisoning.html>,  
<http://blog.acrossecurity.com/2012/02/downloads-folder-binary-planting.html>,  
<http://seclists.org/fulldisclosure/2012/Aug/134> and  
<http://blogs.technet.com/b/srd/archive/2014/05/13/load-library-safely.aspx>  
  
Due to an application manifest embedded in the executable  
installer which specifies "requireAdministrator" it will be  
started with administrative privileges ("protected" administrators  
are prompted for consent, unprivileged standard users are prompted  
for an administrator password), resulting in an escalation of  
privilege!  
  
If (one of) the DLLs named above get(s) planted in the users  
"Downloads" directory, for example per "drive-by download",  
this vulnerability becomes a remote code execution WITH  
escalation of privilege.  
  
  
Proof of concept/demonstration:  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
1. visit <https://skanthak.homepage.t-online.de/sentinel.html>,  
download  
<https://skanthak.homepage.t-online.de/skanthak/download/SENTINEL.DLL>  
and save it as Version.dll in your "Downloads" directory, then  
copy it as OLEACC.dll, CryptBase.dll, NTMARTA.dll, LinkInfo.dll,  
NTSHRUI.dll, NetUtils.dll, SrvCli.dll, CSCAPI.dll, SLC.dll and  
PropSys.dll;  
  
2. visit <https://www.sumatrapdfreader.org/free-pdf-reader.html>,  
download  
<https://kjkpub.s3.amazonaws.com/sumatrapdf/rel/SumatraPDF-3.1.2-install.exe>  
and save it in your "Downloads" directory;  
  
3. execute SumatraPDF-3.1.2-install.exe from your "Downloads"  
directory;  
  
4. notice the message boxes displayed from the DLLs placed in  
step 1: PWNED!  
  
  
The "portable" SumatraPDF.exe version 3.1.2 loads and executes  
at least (tested on a fully patched Windows 7 SP1) WinSpool.drv,  
MSImg32.dll, Version.dll, OLEAcc.dll, WindowsCodecs.dll,  
AppHelp.dll, SrvCli.dll, CSCAPI.dll, SLC.dll, MSFTEdit.dll,  
MSLS31.dll, NTMARTA.dll, XMLLite.dll, LinkInfo.dll, CryptSp.dll,  
RPCRTRemote.dll, ShDocVw.dll, IEFrame.dll, MPR.dll, SAMCli.dll,  
SAMLib.dll, WksCli.dll, NetUtils.dll and WinMM.dll from its  
"application directory" (which is typically writable by the user)  
instead Windows' "system directory", resulting in arbitrary code  
execution.  
  
  
Mitigation(s):  
~~~~~~~~~~~~~~  
  
0. DON'T USE EXECUTABLE INSTALLERS [deg]!  
  
DON'T USE PORTABLE APPLICATIONS!  
  
If your favourite applications are not distributed in the native  
installer package format of the resp. target platform: ask^WURGE  
their vendors/developers to provide native installation packages.  
If they don't: dump these applications, stay away from such cruft!  
  
1. Turn off UAC's privilege elevation for standard users and installer  
detection for all users:  
  
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System]  
"ConsentPromptBehaviorUser"=dword:00000000 ; Automatically deny elevation requests  
"EnableInstallerDetection"=dword:00000000  
  
See <https://technet.microsoft.com/en-us/library/dd835564.aspx#BKMK_RegistryKeys>  
  
2. NEVER execute files in UNSAFE directories (like "Downloads" and  
and "%TEMP%")!  
  
3. Deny execution (at least) in the "Downloads" directories and all  
"%TEMP%" directories and their subdirectories:  
  
* Add the NTFS ACE "(D;OIIO;WP;;;WD)" meaning "deny execution of  
files in this directory for everyone, inheritable to all files  
in all subdirectories" (use CACLS.EXE /S:<SDDL> for example);  
  
* Use "software restriction policies" resp. AppLocker.  
  
Consider to apply either/both to every "%USERPROFILE%" as well as  
"%ALLUSERSPROFILE%" alias %ProgramData%" and "%PUBLIC%": Windows  
doesn't place executables in these directories and beyond.  
  
See <https://skanthak.homepage.t-online.de/SAFER.html> as well as  
<http://www.mechbgon.com/srp/index.html>.  
  
  
stay tuned  
Stefan Kanthak  
  
  
[deg] Self-extracting archives and executable installers are flawed^W  
b(rainde)ad in concept and dangerous in practice: see  
<https://skanthak.homepage.t-online.de/!execute.html>  
  
  
['] A well-known (trivial, easy to exploit and easy to avoid) and  
well-documented vulnerability: see  
<https://cwe.mitre.org/data/definitions/426.html>,  
<https://cwe.mitre.org/data/definitions/427.html>,  
<https://capec.mitre.org/data/definitions/471.html>,  
<https://technet.microsoft.com/en-us/library/2269637.aspx>,  
<https://msdn.microsoft.com/en-us/library/ff919712.aspx> and  
<https://msdn.microsoft.com/en-us/library/ms682586.aspx>  
  
  
Timeline:  
~~~~~~~~~  
  
2017-01-21 sent vulnerability report regarding the installer  
to author  
  
NO ANSWER, not even an acknowledgement of receipt  
  
2017-01-24 sent vulnerability report regarding the "portable"  
version to author  
  
NO ANSWER, not even an acknowledgement of receipt  
  
2017-01-28 resent first vulnerability report to author  
  
NO ANSWER, not even an acknowledgement of receipt  
  
2017-01-31 resent second vulnerability report to author  
  
NO ANSWER, not even an acknowledgement of receipt  
  
2017-02-07 report published  
  
  
  
`