264394 - heap overwrite in NNTP protocol handler

Status: RESOLVED DUPLICATE of bug 264388

(MailNews Core :: Networking: NNTP, defect)

Description

[Daniel Veditz [:dveditz] (OOO: back Aug 26)]

sent to [e-mail]

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Issue:
======

A critical security vulnerability has been found in Mozilla Project code 
handling NNTP protocol.


Details:
========

Mozilla browser supports NNTP urls. Remote side is able to trigger  news:// 
connection to any server. We found a flaw in NNTP handling code which may 
cause heap overflow and allow remote attacker to execute arbitrary code on 
client machine.

Bugus function from nsNNTPProtocol.cpp:

char *MSG_UnEscapeSearchUrl (const char *commandSpecificData)
329 {
330     char *result = (char*) PR_Malloc (PL_strlen(commandSpecificData) + 1);
331     if (result)
332     {
333         char *resultPtr = result;
334         while (1)
335         {
336             char ch = *commandSpecificData++;
337             if (!ch)
338                 break;
339             if (ch == '\\')
340             {
341                 char scratchBuf[3];
342                 scratchBuf[0] = (char) *commandSpecificData++;
343                 scratchBuf[1] = (char) *commandSpecificData++;
344                 scratchBuf[2] = '\0';
345                 int accum = 0;
346                 PR_sscanf(scratchBuf, "%X", &accum);
347                 *resultPtr++ = (char) accum;
348             }
349             else
350                 *resultPtr++ = ch;
351         }
352         *resultPtr = '\0';
353     }
354     return result;
355 }

When commandSpecificData points to last (next is NULL) character which 
is '\\' copying loop may omit termination of source char array and overflow 
result buffer.


Exploitation
============

I have attached proof of concept HTML file which causes heap corruption 
and crashes Mozilla 1.7.3 browser (with mozilla-mail). News server must be 
existing and available.



- -- 
Maurycy Prodeus
iSEC Security Research
http://isec.pl/

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Comment 1

[Daniel Veditz [:dveditz] (OOO: back Aug 26)]

Attachment: crashing example (uses a popup)

Comment 2

[Ben Bucksch (:BenB)]

*** This bug has been marked as a duplicate of 264388 ***