libytnef buffer overflow

2013.04.11

Credit: Igor Vlasenko

Risk: High

Local: Yes

Remote: No

CVE: CVE-2010-5109

CWE: CWE-119

CVSS Base Score: 4.3/10

Impact Subscore: 2.9/10

Exploitability Subscore: 8.6/10

Exploit range: Remote

Attack complexity: Medium

Authentication: No required

Confidentiality impact: None

Integrity impact: None

Availability impact: Partial

Description of problem:
compiler warning: call ... will always overflow destination buffer.
indeed, there is a trivial bug in the code, no space is reserved for trailing \0.
patch to fix:
--- libytnef-1.5/ytnef.c 2004-08-26 17:09:05.000000000 +0000
+++ libytnef-1.5/ytnef.c 2012-06-08 19:34:07.826123387 +0000
@@ -1327,7 +1327,7 @@
ULONG compressedSize, uncompressedSize, magic, crc32;
comp_Prebuf.size = strlen(RTF_PREBUF);
- comp_Prebuf.data = calloc(comp_Prebuf.size, 1);
+ comp_Prebuf.data = calloc(comp_Prebuf.size+1, 1);
strcpy(comp_Prebuf.data, RTF_PREBUF);
src = p->data;
Version-Release number of selected component (if applicable):
libytnef-1.5-7.fc17

References:

https://bugzilla.redhat.com/show_bug.cgi?id=831322

http://lists.fedoraproject.org/pipermail/package-announce/2012-July/083853.html

http://lists.fedoraproject.org/pipermail/package-announce/2012-July/083804.html

https://bugzilla.redhat.com/show_bug.cgi?id=831322

http://sourceforge.net/p/ytnef/bugs/13/

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