Intel Rapid Storage Technology User Interface And Driver DLL Hijacking

Risk: Medium
Local: Yes
Remote: No

CVSS Base Score: 4.6/10
Impact Subscore: 6.4/10
Exploitability Subscore: 3.9/10
Exploit range: Local
Attack complexity: Low
Authentication: No required
Confidentiality impact: Partial
Integrity impact: Partial
Availability impact: Partial

Hi @ll, the executable installer of the Intel(r) Rapid Storage Technology (Intel(r) RST) User Interface and Driver, version (LATEST for Windows 7), released 11/14/2017, available from <> via <> is (SURPRISE!) vulnerable! CVSS score: 7.5/HIGH CVSS:3.0/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H See Intel's security advisory SA-00153 <> Vulnerability #1: ================= Although running with ELEVATED (administrative) privileges (the "application manifest" embedded in SetupRST.exe specifies "requireAdministrator"), on STANDARD installations of Windows, i.e. where the user account created during Windows setup is used, the executable installer creates an UNPROTECTED subdirectory IIF<abcd>.tmp in the user's %TEMP% directory. For this well-known and well-documented vulnerability see <> and <> plus <> The subdirectory IIF<abcd>.tmp inherits the NTFS ACLs from its parent %TEMP%, allowing "full access" for the unprivileged (owning) user, who can replace/overwrite the DLLs %TEMP%\IIF<abcd>.tmp\Resource.dll %TEMP%\IIF<abcd>.tmp\??-??\IntelCommon.dll later loaded and executed by the installer between their creation and use. Since these DLLs are executed with administrative privileges, this vulnerability results in arbitrary code execution WITH escalation of privilege. NOTE: the precondition "user account created during Windows setup" is met on typical installations of Windows: according to Microsoft's own security intelligence reports, about 1/2 to 3/4 of the about 600 million Windows installations which send telemetry data have only ONE active user account. <> Demonstration/proof of concept: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1. visit <>, then download <> and save it in an arbitrary directory; 2. save the following batch script in the same directory: --- IIF.CMD --- :WAIT @If Not Exist "%TEMP%\IIF????.tmp" Goto :WAIT For /D %%! In ("%TEMP%\IIF????.tmp") Do Set IIFTMP=%%! Copy /Y SENTINEL.DLL "%IIFTMP%\Resource.dll" For /R "%IIFTMP%" %%! In (IntelCommon.dll) Do Copy /Y SENTINEL.DLL "%%!" Set IIFTMP= --- EOF --- 3. start the batch script per double-click; 4. execute SetupRST.exe: notice the message boxes displayed from the replaced DLLs. Fixes: ~~~~~~ 1. ALWAYS specify a PROPER "security descriptor" when you create (temporary) files or directories in potentially unsafe (i.e. user-writable) paths like the %TEMP% directory! See <> and use the second parameter of CreateDirectory() to properly restrict the permissions when running elevated! 2. NEVER load resource(-only) DLLs for execution! See <> and use the third parameter of LoadLibraryEx() to specify LOAD_LIBRARY_AS_DATAFILE or LOAD_LIBRARY_AS_IMAGE_RESOURCE Mitigations: ~~~~~~~~~~~~ 1. DONT use executable installers; stay far away from such eternally vulnerable crap! 2. NEVER run executable installers in unsafe environments, especially NEVER from UNSAFE directories like "%TEMP%\" or "%USERPROFILE%\Downloads\" 3. DISABLE execution of files (via NTFS ACL, as shown below) in the systems and every users %TEMP% and every %USERPROFILE% (see <>)! 4. Practice STRICT privilege separation: use a your privileged "Administrator" account (especially the account created during Windows setup) ONLY for administrative tasks, and COMPLETELY separate unprivileged user accounts, with elevation requests DISABLED, for your everyday/regular work. Vulnerability #2: ================= A variant of #1, resulting in denial of service. Demonstration/proof of concept: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1. add the NTFS access control list entry (D;OIIO;WP;;;WD) meaning "deny execution of files in this directory for everyone, inheritable to all subdirectories" to the (user's) %TEMP% directory. NOTE: this does NOT need administrative privileges! 2. execute SetupRST.exe: notice the message box "error loading language resource" displayed. Fix: ~~~~ Create (temporary) files and directories with PROPER permissions! See above. stay tuned Stefan Kanthak Timeline: ~~~~~~~~~ 2018-06-06 vulnerability report sent to vendor 2018-06-10 Intel acknowledges receipt 2018-06-14 Intel confirms reported vulnerability 2018-10-26 CVE-2018-3635 assigned 2018-11-13 Intel publishes security advisory SA-00153 2018-11-16 vulnerability report published

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