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Re: MiniUPnPd Information Disclosure (CVE-2013-2600)
From: Jeffrey Walton <noloader () gmail com>
Date: Fri, 12 Jul 2013 16:32:56 -0400

On Fri, Jul 12, 2013 at 2:16 PM,  <cyoung () tripwire com> wrote:
...

This issue was addressed on April 26, 2013 as noted in the changelog: 
http://miniupnp.free.fr/files/changelog.php?file=miniupnpd-1.8.20130607.tar.gz

2013/04/26:
  Correctly handle truncated snprintf() in SSDP code

The problem is illustrated in the following code snippet:
Minissdp.c:
203 static void SendSSDPAnnounce2(int s, struct sockaddr_in sockname,
204                               const char * st, int st_len,
205                               const char * host, unsigned short port)
206 {
207     int l, n;
208     char buf[512];
209     /* TODO :
210      * follow guideline from document "UPnP Device Architecture 1.0"
211      * put in uppercase.
212      * DATE: is recommended
213      * SERVER: OS/ver UPnP/1.0 miniupnpd/1.0
214      * */
215     l = snprintf(buf, sizeof(buf), "HTTP/1.1 200 OK\r\n"
216         "Cache-Control: max-age=120\r\n"
217         "ST: %.*s\r\n"
218         "USN: %s::%.*s\r\n"
219         "EXT:\r\n"
220         "Server: " MINIUPNPD_SERVER_STRING "\r\n"
221         "Location: http://%s:%u"; ROOTDESC_PATH "\r\n"
222         "\r\n",
223         st_len, st,
224         uuidvalue, st_len, st,
225         host, (unsigned int)port);
226     n = sendto(s, buf, l, 0,
227                (struct sockaddr *)&sockname, sizeof(struct sockaddr_in) );
228 #if 0 //JM: Don't fill up syslog, even in error condition
229     if(n<0)
230     {
231         syslog(LOG_ERR, "sendto: %m");
232     }
233 #endif
234 }


Notice that the sendto on line 226 is using the snprintf return value, l, from line 215 without considering whether l 
sizeof(buf) as is the case when the buffer is truncated.
Truncation occurs at l >= sizeof(buf) since because of the terminating NULL.

Jeff


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