Denial of Service (DoS) Affecting websocket-driver package, versions <0.3.1

websocket-driver is WebSocket protocol handler with pluggable I/O.

Affected versions of this package are vulnerable to Denial of Service (DoS) attacks. The Buffer length is immediately allocated after reading the frame, up to a length that is no more that MAX_LENGTH, which is 2^53 - 1 (the largest precisely representable JS integer), and rejects larger frames with a 1009 error before creating the new Buffer. But Node buffers have a max length of 1GB (0x3fffffff). Parsing an incoming frame with length between 1GB and MAX_LENGTH, the parser will throw (and perhaps crash your whole server). Attackers can use this to their advantage and cause a Denial of Service on the servers.

The Buffer class on Node.js is a mutable array of binary data, and can be initialized with a string, array or number.

const buf1 = new Buffer([1,2,3]);
// creates a buffer containing [01, 02, 03]
const buf2 = new Buffer('test');
// creates a buffer containing ASCII bytes [74, 65, 73, 74]
const buf3 = new Buffer(10);
// creates a buffer of length 10

The first two variants simply create a binary representation of the value it received. The last one, however, pre-allocates a buffer of the specified size, making it a useful buffer, especially when reading data from a stream. When using the number constructor of Buffer, it will allocate the memory, but will not fill it with zeros. Instead, the allocated buffer will hold whatever was in memory at the time. If the buffer is not zeroed by using buf.fill(0), it may leak sensitive information like keys, source code, and system info.

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