WINDOWS 10 POOL CORRUPTION IN FILE AREA DRIVER
WINDOWS 10 POOL CORRUPTION IN FILE AREA CODE
WINDOWS 10 POOL CORRUPTION IN FILE AREA WINDOWS 7
WINDOWS 10 POOL CORRUPTION IN FILE AREA DOWNLOAD

Typically the address is just plain bad or it is pointing at freed memory.ДЄrg2: 00000001, value 0 = read operation, 1 = write operation.ДЄrg3: 94c52169, If non-zero, the instruction address which referenced the bad memory It is advised to enable the Special Pools mechanism for win32k.sys to reliably reproduce the crashes. The first one is caused by an invalid memory write with a partially controlled index (the 'cccc' part in 0x00cccc84), while the second one is due to an attempt to write to a memory region before the allocated output buffer (note the negative 0xfffffeea offset).

WINDOWS 10 POOL CORRUPTION IN FILE AREA WINDOWS 7

Two examples of system bugchecks generated on Windows 7 32-bit are shown below. The last mentioned primitive can be achieved by overwriting an offset stored within the generated PFM structures, that in theory should not be overwritten during the subsequent loops that use it, but it becomes possible with the negative offsets in play. This could in turn lead to various types of pool corruption, such as continuous buffer overflow, buffer underflow, or even a non-continuous overflow with a controlled offset relative to the output buffer. When dfFirstChar is greater than dfLastChar, the result of 'dfLastChar - dfFirstChar' is negative, causing MakePFM() to miscalculate the required size of the output buffer and offsets within it. The result is then used for calculating buffer sizes and offsets in memory. The routine wrongly assumes that dfFirstChar may never be greater than dfLastChar, and so it uses the 'dfLastChar - dfFirstChar' expression in a number of places to determine the number of characters in the font.

WINDOWS 10 POOL CORRUPTION IN FILE AREA CODE

One function that makes use of the saved first/last char indexes is MakePFM(), called by BDMakePFM(), which is the handler function for escape code 0x250D.

MMM files, including scenarios where dfFirstChar > dfLastChar. However, there is no adequate ValidateMMMPointers() function, and so an attacker can set these fields (at offsets 170 and 172) to arbitrary values in. If dfLastChar is not greater or equal to dfFirstChar, the font loading is aborted. PFM files (Type-1 font metrics) have the 8-bit dfFirstChar and dfLastChar fields at offsets 95 and 96, and the internal ValidatePFMPointers() function verifies that dfLastChar >= dfFirstChar: MMM files (Multiple Master Metrics) and specifically the 'first char' and 'last char' fields. The problem discussed in this report is caused by the fact that ATMFD lacks any sort of sanitization of the font metrics found in. All symbols referenced in this report were originally found in fontdrvhost.pdb, but can also be applied to the corresponding code in ATMFD. These two sources of information are invaluable in reverse-engineering the NamedEscape code area.

WINDOWS 10 POOL CORRUPTION IN FILE AREA DRIVER

However, such symbols are available for the ATMLIB.DLL user-mode client library which uses the interface, and more importantly for fontdrvhost.exe, the sandboxed user-mode font driver on Windows 10, which shares most of its code with ATMFD. It is difficult to understand the functionality and design of the various escape codes based on the ATMFD.DLL image alone, as no debug symbols are provided for it on the Microsoft Symbol Server. It is accessible to user-mode applications through an exported (but not documented) gdi32!NamedEscape function, which internally invokes the NtGdiExtEscape syscall. The interface is very similar to Buffered IOCTL in nature, and handles 13 different operation codes in the numerical range of 0x2502 to 0x2514. The OpenType ATMFD.DLL kernel-mode font driver on Windows has an undocumented 'escape' interface, handled by the standard DrvEscape and DrvFontManagement functions implemented by the module.

WINDOWS 10 POOL CORRUPTION IN FILE AREA DOWNLOAD

Change Mirror Download Windows Kernel ATMFD.DLL NamedEscape 0x250D pool corruption due to malformed.

Windows 10 pool corruption in file area