Node Js Php Serialize
Thank you for research to discover and publish this, but I must say, that your title is a bit misleading, or frankly said just sensationalistic and technically wrong. What you describe in the article is simply a bad usage of the infamous `eval` function which is, as to its nature, the easiest way to allow remote code execution.
Untrusted data passed into unserialize function in node-serialize module can be exploited to achieve arbitrary code execution by passing a serialized JavaScript Object with an Immediately invoked function expression (IIFE).
This is covered in dozens of articles and is among the first things every Javascript developer should learn. But most of all the usage is NOT in Node.js itself but in a rather unpopular npm package that was not updated in 4 years and has a mere 11 dependents, according to npmjs.org This is a simple problem with all open source packages: everyone who thinks about using an open source third party dependency should review the source code before trusting it, if used in security context. This is why the `node-serialize` package has no serious dependants as everybody in their right mind would scan a serialization library for the unprotected usage of `eval`. So again, thanks for your work in discovering this, but please adapt the title to the facts! Hi Lukas, This blog post intent to cover deserialization bugs in a fairly new JavaScript environment, Node.js.
As Node.js does not provide serialization/deserialization APIs, there is third party modules providing this functionality to Node.js. The issues discussed in the blog post is present in not just one library, but in other libraries like serialize-to-js as well.
Node Js Vs Php
What you describe in the article is simply a bad usage of the infamous `eval` function which is, as to its nature, the easiest way to allow remote code execution. This is covered in dozens of articles and is among the first things every Javascript developer should learn. This is not so simple and straightforward as that. The unserilalize/deserialize function provided by these modules are designed to convert strings to objects, which may contain functions inside them, but not to execute them.
We are actually abusing the IIFE property to make this into a working exploit. So it is not as simple as old school eval where JavaScript code is passed into eval resulting in code execution. The exploitation technique and payload is different here and is not covered anywhere as far as I know, please correct me if I am wrong. I am a security engineer myself. I don’t know how many developers did a code review on Apache Commons, the Java library known for deserialization issues before using it.
It is not practical in real world for a developer to do code review and then use a library/module. It has to be the job of a security engineer/ consultant to do code review once the code is written and thats how I found this. And finally I agree, the title might be confusing for people who judge early. So I have updated the tl;dr section with enough information to avoid confusion.
Parameters value The value to be serialized. Serialize handles all types, except the -type. You can even serialize arrays that contain references to itself.
Circular references inside the array/object you are serializing will also be stored. Any other reference will be lost. When serializing objects, PHP will attempt to call the member function prior to serialization. This is to allow the object to do any last minute clean-up, etc. Prior to being serialized. Likewise, when the object is restored using the member function is called. Note: Object's private members have the class name prepended to the member name; protected members have a '.'
prepended to the member name. These prepended values have null bytes on either side. DO NOT serialize data and place it into your database. Serialize can be used that way, but that's missing the point of a relational database and the datatypes inherent in your database engine. Neutraface slab rapidshare movies. Doing this makes data in your database non-portable, difficult to read, and can complicate queries. If you want your application to be portable to other languages, like let's say you find that you want to use Java for some portion of your app that it makes sense to use Java in, serialization will become a pain in the buttocks. You should always be able to query and modify data in the database without using a third party intermediary tool to manipulate data to be inserted.
I've encountered this too many times in my career, it makes for difficult to maintain code, code with portability issues, and data that is it more difficult to migrate to other RDMS systems, new schema, etc. It also has the added disadvantage of making it messy to search your database based on one of the fields that you've serialized. That's not to say serialize is useless. A good place to use it may be a cache file that contains the result of a data intensive operation, for instance. There are tons of others.
Node Js Php Serialize Server
Just don't abuse serialize because the next guy who comes along will have a maintenance or migration nightmare. If you are going to serialie an object which contains references to other objects you want to serialize some time later, these references will be lost when the object is unserialized. The references can only be kept if all of your objects are serialized at once. That means: $a = new ClassA; $b = new ClassB($a); //$b containes a reference to $a; $s1=serialize($a); $s2=serialize($b); $a=unserialize($s1); $b=unserialize($s2); now b references to an object of ClassA which is not $a. $a is another object of Class A. Use this: $buf0=$a; $buf1=$b; $s=serialize($buf); $buf=unserialize($s); $a=$buf0; $b=$buf1; all references are intact. When you serialize an array the internal pointer will not be preserved.
Apparently this is the expected behavior but was a bit of a gotcha moment for me. Copy and paste example below. ', printr ( $array, 1 ), ';?. If serializing objects to be stored into a postgresql database, the 'null byte' injected for private and protected members throws a wrench into the system. Even pgescapebytea on the value, and storing the value as a binary type fails under certain circumstances. For a dirty work around: this allows you to store the object in a readable text format as well. When reading the data back: The only gotcha's with this method is if your object member names or values may somehow contain the odd 'NULLBYTE' string.
If that is the case, then strreplace to a string that you are guaranteed not to have any where else in the string that serialize returns. Also remember to define the class before calling unserialize. If you are storing session data into a postgresql database, then this workaround is an absolute must, because the $data passed to the session's write function is already serialized. Thanks, Travis Hegner. I was trying to submit a serialized array through a hidden form field using POST and was having a lot of trouble with the quotes.
I couldn't figure out a way to escape the quotes in the string so that they'd show up right inside the form, so only the characters up to the first set of quotes were being sent. My solution was to base64encode the string, put that in the hidden form field, and send that through the POST method. Then I decoded it (using base64decode) on the other end. This seemed to solve the problem. When using serialize to convert, say, an array to a string to pass via HTML forms, you will likely run into issues with quoting.
This is because serialize puts values in double quotes. The simplest solution is to quote your HTML form value with single quotes rather than double quotes.
(This.is. allowed, according to W3C specs.) So, instead of: you would want to use.