64 lines
2.5 KiB
Plaintext
64 lines
2.5 KiB
Plaintext
CLP-01-001 DOMXSS in Clipperz Bookmarklet via benign HTML Injection (Medium)
|
|
|
|
Insecure concatenation of HTML strings in the Clipperz bookmarklet core
|
|
lead to possibilities for an attacker, to turn a harmless injection on a
|
|
victim website into an XSS as soon as a user activates the bookmarklet.
|
|
The bookmarklet contains injectable code that allows arbitrary
|
|
JavaScript execution from a harmless injection as shown below:
|
|
|
|
PoC:
|
|
(run Clipperz Bookmarklet on this website)
|
|
<body>
|
|
<form action=''>
|
|
<input name='username' type='text'>
|
|
<input name='</textarea><img src=x onerror=alert(domain)>' type='password'>
|
|
</form>
|
|
|
|
Affected HTML:
|
|
<textarea style="border:2px solid #333366; font-family:sans-serif;
|
|
font-size:8pt; color:#336; width:240px; height:135px; padding:4px;
|
|
background-color:white; margin:0px 10px;"
|
|
id="bookmarklet_textarea">{"page": {"title": ""},
|
|
"form": {"attributes": {"action": "http://0x0/Test/",
|
|
"method": null},
|
|
"inputs": [{"type": "text",
|
|
"name": "username",
|
|
"value": "root"},
|
|
{"type": "password",
|
|
"name": "</textarea><img onerror="alert(domain)" src="x">",
|
|
"value": "k4n0n3!?"}]},
|
|
"version": "0.2.3"}</div>
|
|
|
|
Affected Code:
|
|
innerHTML+="<textarea id=\"bookmarklet_textarea\" style=\"border:2px
|
|
solid #333366; font-family:sans-serif; font-size:8pt; color:#336;
|
|
width:240px; height:135px; padding:4px; background-color:white;
|
|
margin:0px 10px;\">"+sj(someParameters)+"</textarea>";}
|
|
|
|
...
|
|
|
|
sj=function(o){var
|
|
objtype=typeof(o);if(objtype=="number"||objtype=="boolean"){return
|
|
o+"";}else if(o===null){return"null";} if(objtype=="string"){return
|
|
rs(o);} var
|
|
me=arguments.callee;if(objtype!="function"&&typeof(o.length)=="number"){var
|
|
res=[];for(var i=0;i<o.length;i++){var
|
|
val=me(o[i]);if(typeof(val)!="string"){val="undefined";} res.push(val);}
|
|
return"["+res.join(",\n")+"]";}
|
|
|
|
...
|
|
|
|
rs=function(o){return("\""+o.replace(/([\"\\])/g,"\\$1")+"\"").replace(/[\f]/g,"\\f").replace(/[\b]/g,"\\b").replace(/[\n]/g,"\\n").replace(/[\t]/g,"\\t").replace(/[\r]/g,"\\r");}
|
|
|
|
Any form of HTML, even content of HTML element attributes must be
|
|
considered an attack vector. Currently, Clipperz does a good job in
|
|
terms of encoding HTML element value attributes, yet other attribute
|
|
types are not escaped, encoded or filtered at all. This lead to the
|
|
identification of this and other bugs, specifically CLP-01-014 and
|
|
CLP-01-015.
|
|
|
|
It needs to be made sure, that any form of user controlled data is being
|
|
processed safely before displaying the resulting data. HTML special
|
|
characters need to be encoded to their respected entity representation
|
|
before displaying them.
|