c# code 128 reader

code 128 barcode reader c#

code 128 barcode reader c#

c# barcode scanner example, c# free barcode reader library, c# code 128 reader, c# code 128 reader, c# code 39 reader, c# code 39 reader, data matrix barcode reader c#, c# data matrix reader, c# gs1 128, c# ean 128 reader, c# ean 13 reader, c# pdf 417 reader, zxing qr code reader example c#, c# upc-a reader

download pdf file from folder in asp.net c#, itextsharp mvc pdf, download pdf in mvc 4, mvc open pdf file in new window, open pdf in new tab c# mvc, asp.net mvc generate pdf from view

c# code 128 reader,
c# code 128 reader,
c# code 128 reader,
c# code 128 reader,
c# code 128 reader,
code 128 barcode reader c#,
code 128 barcode reader c#,
c# code 128 reader,
code 128 barcode reader c#,
c# code 128 reader,
c# code 128 reader,
c# code 128 reader,
c# code 128 reader,
c# code 128 reader,
c# code 128 reader,
code 128 barcode reader c#,
c# code 128 reader,
c# code 128 reader,
c# code 128 reader,
code 128 barcode reader c#,
code 128 barcode reader c#,
c# code 128 reader,
c# code 128 reader,
code 128 barcode reader c#,
c# code 128 reader,
code 128 barcode reader c#,
code 128 barcode reader c#,
code 128 barcode reader c#,
c# code 128 reader,
code 128 barcode reader c#,
code 128 barcode reader c#,
code 128 barcode reader c#,
c# code 128 reader,
code 128 barcode reader c#,
code 128 barcode reader c#,
c# code 128 reader,
code 128 barcode reader c#,
c# code 128 reader,
c# code 128 reader,
code 128 barcode reader c#,
c# code 128 reader,
code 128 barcode reader c#,
code 128 barcode reader c#,
c# code 128 reader,
c# code 128 reader,
code 128 barcode reader c#,
code 128 barcode reader c#,
code 128 barcode reader c#,
code 128 barcode reader c#,

Before you start inspecting DecodeURLEscapes, you must remember that the first parameter it receives is a pointer to the source string, and the third is a pointer to the local variable area in the stack. That local variable is where one expects the function will be writing a decoded copy of the source string. The first parameter is loaded into ESI and the third into EDI. The second parameter is a pointer to the string length and is copied into [ebp-0x10]. So much for setups. The function then gets into a copying loop that copies ASCII characters from ESI into BX (this is that MOVZX instruction at 68cc69b4). It then writes them into the address from EDI as zero-extended 16-bit values (this happens at 68cc6a06). This is simply a conversion into Unicode, where the Unicode string is being written into a local variable whose pointer was passed from CVariableSet::AddExtensionControlBlock. In the process, the function is looking for special characters in the string which indicate special values within the string that need to be decoded (most of the decoding sequences are not included in this listing). The important thing to notice is how the function is decrementing the value at [ebp-0x10] and checking that it s nonzero. You now have a full picture of what causes this bug. CVariableSet::AddExtensionControlBlock is allocating what seems to be a 400-bytes-long buffer that receives the decoded string from Decode URLEscapes. The function is checking that the source string (which is in ASCII) is 400 characters long, but DecodeURLEscapes is writing the string in Unicode! Most likely the buffer in CVariableSet::AddExtensionControlBlock was defined as a 200-character Unicode string (usually defined using the WCHAR type). The bug is that the length comparison is confusing bytes with Unicode

0.1 0.08 0.06 0.04 0.02 0

7

19

asp.net upc-a, winforms ean 13 reader, crystal reports code 39, .net upc-a reader, word pdf 417, asp.net qr code reader

characters The buffer can only hold 200 Unicode characters, but the check is going to allow 400 characters As with many buffer overflow conditions, exploiting this bug isn t as easy as it seems First of all, whatever you do you wouldn t be able to affect Decode URLEscapes, only CVariableSet::AddExtensionControlBlock That s because the vulnerable local variable is part of CVariableSet::Add ExtensionControlBlock s stack area, and DecodeURLEscapes stores its local variables in a lower address in the stack You can overwrite as many as 400 bytes of stack space beyond the end of the WCHAR local variable (that s the difference between the real buffer size and the maximum bytes the boundary check would let us write) This means that you can definitely get to CVariableSet::AddExtensionControlBlock s return value, and probably to the return values of several calls back It turns out that it s not so simple.

n = 10

First of all, take a look at what CVariableSet::AddExtensionControl Block does after DecodeURLEscapes returns Assuming that the function succeeds, it goes on to perform some additional processing on the converted string (it calls DecodeHtmlNumeric and wcsupr to convert the string to uppercase) In most cases, these operations will be unaffected by the fact that the stack has been overwritten, so the function will simply keep on running The trouble starts afterward, at 6e90088f when the function is reading the pointer to EXTENSION_CONTROL_BLOCK from [ebp+0x8] there is no way to modify the function s return value without affecting this parameter That s because even if the last bit of data transmitted is a carefully selected return address for CVariableSet::AddExtensionControlBlock, DecodeURLEscapes would still overwrite 2 bytes at [ebp+0x8] when it adds a Unicode NULL terminator This creates a problem because the function tries to access the EXTENSION _CONTROL_BLOCK before it returns.

n = 100

Corrupting the pointer at [ebp+0x8] means that the function will crash before it jumps to the new return value (this will probably happen at 6e900896, when the function tries to access offset +8 in that structure) The solution here is to use the exception handler pointer instead of the function s return value If you go back to the beginning of CVariable Set::AddExtensionControlBlock, you ll see that it starts by setting EAX to 0x6e906af8 and then calls idq!_EH_prolog This sequence sets up exception handling for the function 0x6e906af8 is a pointer to code that the system will execute in case of an exception The call to idq!_EH_prolog is essentially pushing exception-handling information into the stack The system is keeping a pointer to this stack address in a special memory location that is accessed through fs:[0].

When the buffer overflow occurs, it s also overwriting this exception-handling data structure, and you can replace the exception handler s address with whatever you wish This way, you don t have to worry about corrupting the.

Advice from Joe Glanfield:

n = 1000

c# .net core barcode generator, c# .net core barcode generator, birt code 128, birt data matrix