Google Chrome DLL Hijack

Type packetstorm
Reporter Stefan Kanthak
Modified 2015-12-11T00:00:00


                                            `Hi @ll,  
the executable installers [°] of Google Chrome are vulnerable:  
1. ChromeStandaloneSetup.exe and ChromeSetup.exe load and execute  
a rogue/bogus/malicious CryptBase.dll (under Windows NT6.x)  
from their "application directory" ['].  
For software downloaded with a web browser this is typically the  
"Downloads" directory: see  
and <>  
If CryptBase.dll gets planted in the "Downloads" directory per  
"drive-by download" this vulnerability becomes a remote code  
2. Their "final" executable installer setup.exe loads and executes  
the rogue/bogus/malicious RichEd20.dll, ClbCatQ.dll and XPSP2Res.dll  
(both only under NT5.x, not under NT6.x) and SetupAPI.dll (the  
latter only under NT6.x, not under NT5.x) from its "application  
directory" ['] %TEMP%\CR_<random>.tmp\  
XPSP2Res.dll is not present in Windows Vista and newer versions  
where it is loaded from the DLL search path.  
Since setup.exe is typically run with administrative (or SYSTEM)  
privileges this results in an escalation of privilege.  
%TEMP%\CR_<random>.tmp\setup.exe as well as  
%TEMP%\CR_<random>.tmp\CHROME.PACKED.7Z are extracted to this  
unsafe temporary directory [²] by Chrome's installer^Wself-  
extractor 46.0.2490.86_chrome_installer.exe (at the time of  
The current self-extractor is downloaded and run from Google's  
The Google Updater is installed during the first run of  
ChromeSetup.exe, Chrome's online installer stub, available via  
3. Bonus point: on Windows XP with Internet Explorer 6 installed  
setup.exe loads and executes IEFrame.dll (which is not present  
before Internet Explorer 7) from the DLL search path.  
Proof of concept/demonstration:  
1. visit <>, download  
<> and save  
it as CryptBase.dll in your "Downloads" directory;  
2. download ChromeSetup.exe and/or ChromeStandaloneSetup.exe  
(via <>)  
and save it in your "Downloads" directory;  
3. execute ChromeSetup.exe and/or ChromeStandaloneSetup.exe  
from your "Downloads" directory;  
4. notice the message boxes displayed from CryptBase.dll placed in  
step 1.  
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:  
"ConsentPromptBehaviorUser"=dword:00000000 ; Automatically deny elevation requests  
See <>  
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 <> as well as  
<> plus  
or <> and finally  
stay tuned  
Stefan Kanthak  
PS: see <> (resp. the  
not yet finished <!execute.html>)  
for more details!  
PPS: the case numbers are not in chronological order.  
[°] Self-extracting archives and executable installers are flawed^W  
b(rainde)ad in concept and dangerous in practice.  
ALWAYS use the resp. target platforms native package and archive  
For Windows these are .INF (plus .CAB) and .MSI (plus .CAB),  
introduced 20 years ago (with Windows 95 and Windows NT4) resp.  
16 years ago (with Office 2000).  
Both .INF and .MSI are "opened" by programs residing in  
%SystemRoot%\System32\ which are therefore immune to this kind  
of "DLL and EXE Search Order Hijacking" attack.  
Since both .INF and .MSI access the contents of .CAB directly  
they eliminate the attack vector "unsafe temporary directory"  
['] A well-known (trivial, easy to exploit and easy to avoid) and  
well-documented vulnerability: see  
<> and  
[²] Another well-known (trivial, easy to exploit and easy to avoid)  
and well-documented vulnerability: see  
<> ...  
2015-11-20 vulnerability report sent to Google Security  
2015-11-20 receipt of report acknowledged  
2015-11-27 vulnerability report resent to Chromium  
2015-12-01 response:  
"we don't care for physically-local attacks"  
2015-12-01 reality check, PLEASE!  
NO ANSWER, not even an acknowledgement of receipt  
2015-12-09 report published