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Credit:
The information has been provided by iDefense.
The original article(s) can be found at:
http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=433
http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=434
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Vulnerable Systems:
* WV library version 1.2.2.
* Earlier versions are suspected to be vulnerable as well.
LFO Count Integer Overflow Vulnerability:
When parsing documents, two user supplied integer values are multiplied without checking for an overflow condition.
89 int
90 wvGetLFO_PLF (LFO ** lfo, U32 * nolfo, U32 offset, U32 len, wvStream * fd)
...
101 *nolfo = read_32ubit (fd);
...
104 *lfo = (LFO *) wvMalloc (*nolfo * sizeof (LFO));
...
112 for (i = 0; i < *nolfo; i++)
113 wvGetLFO (&((*lfo)[i]), fd);
As can be seen from the source code above, an attacker supplied integer value is read from the file on line 101. On line 104, memory for that number of structures is allocated based on the supplied number multiplied by the size of the structures. Any value larger than 2^^32 / sizeof(LFO) will cause an integer overflow. Lines 112 and 113 show the loop used for reading data into the newly allocated heap buffer. When integer overflow occurs, the loop will store data beyond the end of the allocated heap buffer.
LVL Count Integer Overflow Vulnerability:
When parsing documents, an attacker supplied integer value is multiplied with a constant without checking for an overflow condition.
35 int
36 wvGetLFO_records (LFO ** lfo, LFOLVL ** lfolvl, LVL ** lvl, U32 *nolfo,
37 U32 * nooflvl, U32 offset, U32 len, wvStream *fd)
38 {
..
47 for (i = 0; i < *nolfo; i++)
48 *nooflvl += (*lfo)[i].clfolvl;
..
59 *lfolvl = (LFOLVL *) wvMalloc (sizeof (LFOLVL) * *nooflvl);
60 *lvl = (LVL *) wvMalloc (sizeof (LVL) * *nooflvl);
On lines 47 and 48, a loop of '*nolfo' iterations increments '*nooflvl' by an attacker supplied 8-bit value read from the file. Lines 59 and 60 will use the calculated value to allocate memory for two different dynamic structure arrays. Since no input validation is done, integer overflow can occur. If an integer overflow, or wrap-around, does occur it will lead to a heap overflow situation.
A remote attacker could execute arbitrary code as a user that uses a WV library dependent product to handle a malicious Microsoft Word document.
CVE Information:
CVE-2006-4513
Vendor Status:
The wvWare maintainers have addressed this vulnerability by releasing version 1.2.3.
Disclosure Timeline:
* - 08/17/2006 Initial vendor notification
* - 10/18/2006 Initial vendor response
* - 10/18/2006 Second vendor notification
* - 10/26/2006 Coordinated public disclosure
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