mirror of https://github.com/calzoneman/sync.git
Replace XSS filter with sanitize-html
This commit is contained in:
Calvin Montgomery
calzoneman
parent
8630c5972c
commit
1c3a669279
|
|
@ -36,9 +36,11 @@ CustomizationModule.prototype.load = function (data) {
|
|||
|
||||
if ("motd" in data) {
|
||||
this.motd = {
|
||||
motd: data.motd.motd || "",
|
||||
html: data.motd.html || ""
|
||||
motd: data.motd.motd || ""
|
||||
};
|
||||
|
||||
this.motd.motd = XSS.sanitizeHTML(this.motd.motd);
|
||||
this.motd.html = this.motd.motd.replace(/\n/g, "<br>");
|
||||
}
|
||||
};
|
||||
|
||||
|
|
|
|||
307
lib/xss.js
307
lib/xss.js
|
|
@ -1,260 +1,62 @@
|
|||
/*
|
||||
WARNING
|
||||
var sanitizeHTML = require("sanitize-html");
|
||||
|
||||
This file contains an XSS prevention module I wrote myself. It has not
|
||||
been verified by any external agency, and due to the nature of XSS I cannot
|
||||
guarantee that it will filter correctly. Feel free to send me bug reports
|
||||
and I will do my best to fix them, but use at your own risk.
|
||||
const ALLOWED_TAGS = [
|
||||
"button",
|
||||
"center",
|
||||
"details",
|
||||
"font",
|
||||
"h1",
|
||||
"h2",
|
||||
"img",
|
||||
"marquee", // It pains me to do this, but a lot of people use it...
|
||||
"section",
|
||||
"span",
|
||||
"summary"
|
||||
];
|
||||
|
||||
*/
|
||||
|
||||
/* Prototype for a basic XML tag parser */
|
||||
function TagParser(text) {
|
||||
this.text = text;
|
||||
this.i = 0;
|
||||
this.tag = this.parse();
|
||||
}
|
||||
|
||||
/* Moves the position marker past any whitespace characters */
|
||||
TagParser.prototype.skipWhitespace = function () {
|
||||
while (this.i < this.text.length && this.text[this.i].match(/\s/)) {
|
||||
this.i++;
|
||||
}
|
||||
};
|
||||
|
||||
/* Reads a literal value matching the given regexp. Defaults
|
||||
to /[^\s>]/; i.e. any string not containing whitespace or
|
||||
the end of tag character '>'
|
||||
*/
|
||||
TagParser.prototype.readLiteral = function (regexp) {
|
||||
if (regexp === void 0) {
|
||||
regexp = /[^\s>]/;
|
||||
}
|
||||
var str = "";
|
||||
while (this.i < this.text.length && this.text[this.i].match(regexp)) {
|
||||
str += this.text[this.i];
|
||||
this.i++;
|
||||
}
|
||||
|
||||
str = str.replace(/&#([0-9]{2,7});?/g, function (m, p1) {
|
||||
return String.fromCharCode(parseInt(p1));
|
||||
});
|
||||
|
||||
str = str.replace(/&#x([0-9a-fA-F]{2,7});?/g, function (m, p1) {
|
||||
return String.fromCharCode(parseInt(p1, 16));
|
||||
});
|
||||
|
||||
str = str.replace(/[\x00-\x1f]/g, "");
|
||||
return str;
|
||||
};
|
||||
|
||||
/* If the character at the current position is a quote, read
|
||||
a string. Otherwise, read a literal
|
||||
*/
|
||||
TagParser.prototype.readLiteralOrString = function (regexp) {
|
||||
if (this.text[this.i].match(/["'`]/)) {
|
||||
return this.readString();
|
||||
}
|
||||
return this.readLiteral(regexp);
|
||||
};
|
||||
|
||||
/* Read a string delimited by the character at the current
|
||||
position. For XML tags this means strings enclosed in
|
||||
" or '. Treats \" as a literal '"' symbol and not a
|
||||
delimiter.
|
||||
*/
|
||||
TagParser.prototype.readString = function () {
|
||||
var delim = this.text[this.i++];
|
||||
|
||||
var str = "";
|
||||
while (this.i < this.text.length && this.text[this.i] !== delim) {
|
||||
if (this.text[this.i] === "\\" && this.text[this.i+1] === delim) {
|
||||
str += this.text[this.i+1];
|
||||
this.i++;
|
||||
} else {
|
||||
str += this.text[this.i];
|
||||
}
|
||||
this.i++;
|
||||
}
|
||||
this.i++;
|
||||
|
||||
str = str.replace(/&#([0-9]{2,7});?/g, function (m, p1) {
|
||||
return String.fromCharCode(parseInt(p1));
|
||||
});
|
||||
|
||||
str = str.replace(/&#x([0-9a-fA-F]{2,7});?/g, function (m, p1) {
|
||||
return String.fromCharCode(parseInt(p1, 16));
|
||||
});
|
||||
|
||||
str = str.replace(/[\x00-\x1f]/g, "");
|
||||
return str;
|
||||
};
|
||||
|
||||
/* Attempts to parse a tagname and attributes from an
|
||||
XML tag.
|
||||
NOTE: Does not actually parse a DOM node, only parses
|
||||
the tag between '<' and '>' because that's all I need
|
||||
to do XSS filtering, I don't care what's between a tag
|
||||
and its end tag (if it's another tag I handle that
|
||||
separately)
|
||||
*/
|
||||
TagParser.prototype.parse = function () {
|
||||
this.i = this.text.indexOf("<");
|
||||
// Not a tag
|
||||
if (this.i === -1) {
|
||||
return null;
|
||||
}
|
||||
|
||||
this.i++;
|
||||
this.skipWhitespace();
|
||||
|
||||
// First non-whitespace string after the opening '<' is the tag name
|
||||
var tname = this.readLiteral();
|
||||
|
||||
var attrs = {};
|
||||
// Continue parsing attributes until the end of string is reached or
|
||||
// the end of tag is reached
|
||||
while (this.i < this.text.length && this.text[this.i] !== ">") {
|
||||
// Read any string not containing equals, possibly delimited by
|
||||
// " or '
|
||||
var key = this.readLiteralOrString(/[^\s=>]/);
|
||||
this.skipWhitespace();
|
||||
// It's possible for tags to have attributes with no value, where
|
||||
// the equals sign is not necessary
|
||||
if (this.text[this.i] !== "=") {
|
||||
if (key.trim().length > 0) {
|
||||
attrs[key] = "";
|
||||
}
|
||||
continue;
|
||||
}
|
||||
|
||||
this.i++;
|
||||
//this.skipWhitespace();
|
||||
var value = this.readLiteralOrString();
|
||||
if (key.trim().length > 0) {
|
||||
attrs[key] = value;
|
||||
}
|
||||
this.skipWhitespace();
|
||||
}
|
||||
|
||||
// If end-of-string was not reached, consume the ending '>'
|
||||
if (this.i < this.text.length) {
|
||||
this.i++;
|
||||
}
|
||||
|
||||
return {
|
||||
tagName: tname,
|
||||
attributes: attrs,
|
||||
text: this.text.substring(0, this.i) // Original text (for replacement)
|
||||
};
|
||||
};
|
||||
|
||||
/* Some of these may not even be HTML tags, I borrowed them from the
|
||||
[now deprecated] XSS module of node-validator
|
||||
*/
|
||||
const badTags = new RegExp([
|
||||
"alert",
|
||||
"applet",
|
||||
"audio",
|
||||
"basefont",
|
||||
"base",
|
||||
"behavior",
|
||||
"bgsound",
|
||||
"blink",
|
||||
"body",
|
||||
"embed",
|
||||
"expression",
|
||||
"form",
|
||||
"frameset",
|
||||
"frame",
|
||||
"head",
|
||||
"html",
|
||||
"ilayer",
|
||||
"iframe",
|
||||
"input",
|
||||
"layer",
|
||||
"link",
|
||||
"meta",
|
||||
"object",
|
||||
const ALLOWED_ATTRIBUTES = [
|
||||
"id",
|
||||
"aria-hidden",
|
||||
"border",
|
||||
"class",
|
||||
"color",
|
||||
"data-dismiss",
|
||||
"data-target",
|
||||
"height",
|
||||
"role",
|
||||
"style",
|
||||
"script",
|
||||
"textarea",
|
||||
"title",
|
||||
"video",
|
||||
"xml",
|
||||
"xss"
|
||||
].join("|"), "i");
|
||||
"valign",
|
||||
"width"
|
||||
];
|
||||
|
||||
/* Nasty attributes. Anything starting with "on" is probably a javascript
|
||||
callback, and I hope you see why formaction is a bad idea.
|
||||
*/
|
||||
const badAttrs = new RegExp([
|
||||
"\\bon\\S*",
|
||||
"\\bformaction",
|
||||
"\\baction"
|
||||
].join("|"), "i");
|
||||
|
||||
function sanitizeHTML(str) {
|
||||
var i = str.indexOf("<");
|
||||
if (i === -1) {
|
||||
// No HTML tags in the string
|
||||
return str;
|
||||
}
|
||||
|
||||
// Loop across all tag delimiters '<' in string, parse each one,
|
||||
// and replace the results with sanitized tags
|
||||
while (i !== -1) {
|
||||
var t = new TagParser(str.substring(i)).tag;
|
||||
if (t.tagName.replace("/", "").match(badTags)) {
|
||||
// Note: Important that I replace the tag with a nonempty value,
|
||||
// otherwise <scr<script>ipt> would possibly defeat the filter.
|
||||
str = str.replace(t.text, "[tag removed]");
|
||||
i = str.indexOf("<", i+1);
|
||||
continue;
|
||||
}
|
||||
for (var k in t.attributes) {
|
||||
// Keys should not contain non-word characters.
|
||||
var k2 = k.replace(/[^\w]/g, "");
|
||||
if (k2 !== k) {
|
||||
t.attributes[k2] = t.attributes[k];
|
||||
delete t.attributes[k];
|
||||
k = k2;
|
||||
}
|
||||
// If it's an evil attribute, just nuke it entirely
|
||||
if (k.match(badAttrs)) {
|
||||
delete t.attributes[k];
|
||||
} else {
|
||||
if (t.attributes[k].replace(/\s/g, "").indexOf("javascript:") !== -1) {
|
||||
t.attributes[k] = "[removed]";
|
||||
}
|
||||
|
||||
}
|
||||
}
|
||||
// Build the sanitized tag
|
||||
var fmt = "<" + t.tagName;
|
||||
for (var k in t.attributes) {
|
||||
if (k.trim().length > 0) {
|
||||
fmt += " " + k;
|
||||
if (t.attributes[k].trim().length > 0) {
|
||||
var delim = '"';
|
||||
if (t.attributes[k].match(/[^\\]"/)) {
|
||||
delim = "'";
|
||||
if (t.attributes[k].match(/[^\\]'/)) {
|
||||
delim = "`";
|
||||
}
|
||||
}
|
||||
fmt += "=" + delim + t.attributes[k] + delim;
|
||||
}
|
||||
}
|
||||
}
|
||||
str = str.replace(t.text, fmt + ">");
|
||||
i = str.indexOf("<", i + fmt.length + 1);
|
||||
}
|
||||
|
||||
return str;
|
||||
var ATTRIBUTE_MAP = {
|
||||
a: ["href", "name", "target"],
|
||||
font: ["size"],
|
||||
img: ["src"],
|
||||
marquee: ["behavior", "behaviour", "direction", "scrollamount"],
|
||||
table: ["cellpadding", "cellspacing"],
|
||||
th: ["colspan", "rowspan"],
|
||||
td: ["colspan", "rowspan"]
|
||||
}
|
||||
|
||||
/* WIP: Sanitize a string where HTML is prohibited */
|
||||
for (var key in ATTRIBUTE_MAP) {
|
||||
ALLOWED_ATTRIBUTES.forEach(function (attr) {
|
||||
ATTRIBUTE_MAP[key].push(attr);
|
||||
});
|
||||
}
|
||||
|
||||
sanitizeHTML.defaults.allowedTags.concat(ALLOWED_TAGS).forEach(function (tag) {
|
||||
if (!(tag in ATTRIBUTE_MAP)) {
|
||||
ATTRIBUTE_MAP[tag] = ALLOWED_ATTRIBUTES;
|
||||
}
|
||||
});
|
||||
|
||||
const SETTINGS = {
|
||||
allowedTags: sanitizeHTML.defaults.allowedTags.concat(ALLOWED_TAGS),
|
||||
allowedAttributes: ATTRIBUTE_MAP
|
||||
};
|
||||
|
||||
function sanitizeText(str) {
|
||||
str = str.replace(/&/g, "&")
|
||||
.replace(/</g, "<")
|
||||
|
|
@ -280,6 +82,9 @@ function decodeText(str) {
|
|||
return str;
|
||||
}
|
||||
|
||||
module.exports.sanitizeHTML = sanitizeHTML;
|
||||
module.exports.sanitizeHTML = function (html) {
|
||||
return sanitizeHTML(html, SETTINGS);
|
||||
};
|
||||
|
||||
module.exports.sanitizeText = sanitizeText;
|
||||
module.exports.decodeText = decodeText;
|
||||
|
|
|
|||
|
|
@ -22,6 +22,7 @@
|
|||
"nodemailer": "^1.2.0",
|
||||
"oauth": "^0.9.12",
|
||||
"q": "^1.0.1",
|
||||
"sanitize-html": "^1.4.3",
|
||||
"serve-static": "^1.5.3",
|
||||
"socket.io": "^1.2.1",
|
||||
"yamljs": "^0.1.5"
|
||||
|
|
|
|||
Loading…
Reference in New Issue