amrapali builders@@@@hacking windows internals.pdf
- 1. Briefing for: Hacking Windows Internals Cesar CerrudoCesar Cerrudo ArgenissArgeniss
- 2. www.appsecinc.com Hacking Shared Sections Shared Section definition Using Shared Sections Tools Problems Searching for holes Exploitation Conclusions References
- 3. www.appsecinc.com Shared Section Basically a Shared Section is a portion of memory shared by a process, mostly used as an IPC (Inter Process Communication) mechanism. Shared Memory. File Mapping. Named or Unnamed.
- 4. www.appsecinc.com Using Shared Sections Loading binary images by OS. Process creation. Dll loading. Mapping kernel mode memory into user address space !?. Used to avoid kernel transitions. Sharing data between processes. GDI and GUI data, pointers !?, counters, any data.
- 5. www.appsecinc.com Using Shared Sections Creating a shared section HANDLE CreateFileMapping( HANDLE hFile, // handle to file (file mapping) //or 0xFFFFFFFF (shared memory) LPSECURITY_ATTRIBUTES lpAttributes, // security DWORD flProtect, // protection DWORD dwMaximumSizeHigh, // high-order DWORD of size DWORD dwMaximumSizeLow, // low-order DWORD of size LPCTSTR lpName // object name (named) //or NULL (unnamed) );//returns a shared section handle
- 6. www.appsecinc.com Using Shared Sections Opening an existing shared section HANDLE OpenFileMapping( DWORD dwDesiredAccess, // access mode (FILE_MAP_WRITE // FILE_MAP_READ, etc.) BOOL bInheritHandle, // inherit flag LPCTSTR lpName // shared section name );//returns a shared section handle
- 7. www.appsecinc.com Using Shared Sections Mapping a shared section LPVOID MapViewOfFile( HANDLE hFileMappingObject, // handle to created/opened // shared section DWORD dwDesiredAccess, // access mode(FILE_MAP_WRITE // FILE_MAP_READ, etc.) DWORD dwFileOffsetHigh, // high-order DWORD of offset DWORD dwFileOffsetLow, // low-order DWORD of offset SIZE_T dwNumberOfBytesToMap // number of bytes to map ); //returns a pointer to begining of shared section memory
- 8. www.appsecinc.com Using Shared Sections Ntdll.dll Native API NtCreateSection() Creates a new section NtOpenSection() Opens an existing section NtMapViewOfSection() Map a section on memory NtUnmapViewOfSection() Unmap a section from memory NtQuerySection() Returns section size NtExtendSection() Change section size
- 9. www.appsecinc.com Using Shared Sections Mapping unnamed Shared Sections. OpenProcess(PROCESS_DUP_HANDLE,...) DuplicateHandle(...) MapViewOfFile(...) Need permissions on target process
- 11. www.appsecinc.com Tools Process Explorer Shows information about processes (dlls, handles, etc.). WinObj Shows Object Manager Namespace information (objects info, permissions, etc.) ListSS Lists Shared Sections names (local and TS sessions). DumpSS Dumps Shared Section data. TestSS Overwrites Shared Section data (to detect bugs)
- 13. www.appsecinc.com Problems Input validation Applications don't perform data validation before using the data. Processes trust data on shared sections.
- 14. www.appsecinc.com Problems Weak permissions Low privileged users can access (read/write/change permissions) shared sections on high privileged processes (services). Terminal Services (maybe Citrix) users can access (read/write/change permissions) shared sections on local logged on user processes, services and other user sessions.
- 16. www.appsecinc.com Problems Synchronization Not built-in synchronization. Synchronization must be done by processes in order to not corrupt data. There isn't a mechanism to force processes to synchronize or to block shared section access. Any process (with proper rights) can alter a shared section data while another process is using it.
- 17. www.appsecinc.com Problems Synchronization Communication between Process A and B Proces s A Proces s B Proces s C Shared Section 2- Write data. 3- Data ready. 4- Replace data. 5- Read data. 1- Send me data.
- 18. www.appsecinc.com Searching for holes Look for shared sections using Process Explorer or ListSS. Attach a process using the shared section to a debugger. Run TestSS on shared section. Interact with process in order to make it use (read/write) the shared section. Look at debugger for crashes :).
- 20. www.appsecinc.com Exploitation Elevating privileges. Reading data. Altering data. Shared section exploits. Using shared sections on virus/rootkits/ etc.
- 21. www.appsecinc.com Exploitation Reading data. From high privileged processes (services). From local logged on user processes, services and other sessions on Terminal Services. This leads to unauthorized access to data.
- 22. www.appsecinc.com Exploitation Reading data. Reading Internet Explorer cookies and history information. (Demo)
- 23. www.appsecinc.com Exploitation Altering data. On high privileged processes (services). On local logged on user processes, services and other sessions on Terminal Services. This leads to arbitrary code execution, unauthorized access, processes or kernel crashing (DOS).
- 24. www.appsecinc.com Exploitation Altering data. IIS 5 DOS. (Demo)
- 25. www.appsecinc.com Exploitation Shared section exploits. When overwriting shared section data allow us to take control of code execution. Some shared sections start addresses are pretty static on same OS and Service Pack. Put shellcode on shared section. Build exploit to jump to shellcode on shared section at static location.
- 26. www.appsecinc.com Exploitation Shared section exploits. MS05-012 - COM Structured Storage Vulnerability Exploit (Demo)
- 27. www.appsecinc.com Exploitation Using shared sections on virus/rootkits/etc. Some shared sections are used by many processes (InternatSHData used for Language Settings) others are used by all processes :). Write code to shared section and the code will be instantly mapped on processes memory and also on new created processes. Use SetThreadContext() or CreateRemoteThread() to start executing code. Similar to WriteProcessMemory() - SetThreadContext() technique or DLL Injection.
- 28. www.appsecinc.com Exploitation Using shared sections on virus/rootkits/etc. Some shared sections have execute access. It would be possible to avoid WinXP sp2 NX .
- 29. www.appsecinc.com Conclusions Windows and 3rd. Party applications have a bunch of Shared Section related holes. These kind of holes will lead to new kind of attacks “SSAtacks” (Shared Section Attacks) ;) Microsoft forgot to include a Shared Sections audit on the trustworthy computing initiative :). Windows guts are rotten:).
- 30. www.appsecinc.com References MSDN Programming Applications for MS Windows - Fourth Edition Process Explorer (www.sysinternals.com) WinObj (www.sysinternals.com) Rattle - Using Process Infection to Bypass Windows Software Firewalls (PHRACK #62) Crazylord - Playing with Windows /dev/(k)mem (PHRACK #59)
- 31. Click to edit Master title style Click to edit Master subtitle style Briefing for: FIN • Questions? • Thanks. • Contact: sqlsec>at<yahoo>dot<com • Argeniss – http://www.argenis.com