Tcpdump Off-by-One Heap Overflow Lets Remote Users Deny Service
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SecurityTracker Alert ID: 1017717
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SecurityTracker URL: http://securitytracker.com/id?1017717
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CVE Reference: CVE-2007-1218
(Links to External Site)
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Updated: Mar 7 2007
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Original Entry Date: Mar 2 2007
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Impact: Denial of service via network
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Fix Available: Yes
Vendor Confirmed: Yes
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Version(s): 3.9.5
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Description: A vulnerability was reported in tcpdump. A remote user can cause denial of service conditions.
A remote user can send a specially crafted 802.11 frame to trigger an off-by-one heap overflow in the function parse_elements() function
in 'print-802_11.c' and cause the process to crash.
Moritz Jodeit reported this vulnerability.
[Editor's note: The report
did not indicate whether code execution is possible or not. Also, CVE indicates that the overflow may be stack-based.]
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Impact: A remote user can cause denial of service conditions.
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Solution: The vendor has issued a fix, available via CVS:
http://cvs.tcpdump.org/cgi-bin/cvsweb/tcpdump/print-802_11.c?r1=1.42&r2=1.43
The tcpdump_3_9 branch also contains the fix.
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Vendor URL: www.tcpdump.org/ (Links to External Site)
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Cause: Boundary error
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Underlying OS: Linux (Any), UNIX (Any)
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Reported By: Moritz Jodeit <moritz@jodeit.org>
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Message History:
This archive entry has one or more follow-up message(s) listed below.
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Source Message Contents
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Date: Thu, 1 Mar 2007 13:59:23 +0100
From: Moritz Jodeit <moritz@jodeit.org>
Subject: [Full-disclosure] tcpdump: off-by-one heap overflow in 802.11
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There's an off-by-one heap-overflow in the ieee802.11 printer,
which can be triggered by a maliciously crafted 802.11 frame.
The link type must have been explicitly specified for this to
work.
The function parse_elements() in print-802_11.c checks the
length pbody->tim.length from the frame for too small values in
line 265, but then uses the wrong variable in the following
range check in line 267. Since pbody->tim.length is defined as
a u_int8_t it can hold a maximum value of 255, which in turn
would copy 252 bytes into pbody->tim.bitmap, which is only
251 bytes of size.
253 case E_TIM:
254 /* Present, possibly truncated */
255 pbody->tim_status = TRUNCATED;
256 if (!TTEST2(*(p + offset), 2))
257 return;
258 memcpy(&pbody->tim, p + offset, 2);
259 offset += 2;
260 if (!TTEST2(*(p + offset), 3))
261 return;
262 memcpy(&pbody->tim.count, p + offset, 3);
263 offset += 3;
264
265 if (pbody->tim.length <= 3)
266 break;
267 if (pbody->rates.length > sizeof pbody->tim.bitmap)
268 return;
269 if (!TTEST2(*(p + offset), pbody->tim.length - 3))
270 return;
271 memcpy(pbody->tim.bitmap, p + (pbody->tim.length - 3),
272 (pbody->tim.length - 3))
The current tcpdump release 3.9.5 is still vulnerable.
This got fixed [1] in CVS Head and in the tcpdump_3_9 branch.
[1] http://cvs.tcpdump.org/cgi-bin/cvsweb/tcpdump/print-802_11.c?r1=1.42&r2=1.43
Best,
Moritz Jodeit
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