=======================================================
The latest version of this advisory is available at:
https://sintonen.fi/advisories/nicehash-miner-excavator-api-csrf.txt
Overview
--------
NiceHash Miner Excavator plugin contains a vulnerability that
enables any external
web site to send commands to the local miner instance, and to
redirect the mined
coins to arbitrary mining address.
Description
-----------
NiceHash Miner Excavator plugin uses a local JSON API at
localhost:4000. External
javascript (any website browsed by the victim) can craft and send
JSON requests to
the API endpoint by employing XMLHTTPRequest objects.
Impact
------
Malicious website can command the NiceHash Excavator miner to
send the coins to
an arbitrary mining address, effectively stealing the mined
coins.
Details
-------
The discovered vulnerability, described in more detail below,
enables the attack
described here in brief.
1. The attacker creates a JavaScript payload that uses
XMLHTTPRequest object to
send JSON API commands to localhost:4000 API endpoint. Note that
the API
expects a raw TCP connection but since the parser is relaxed, it
will skip any
non-JSON input such as the GET line and the HTTP header lines until
the actual
HTTP POST data is met. Additionally since there is no need to
specify a
Content-Type for the request, no Cross-Origin Resource Sharing
preflight check
is needed or performed. The payload uses the 'subscribe' API method
to connect
the miner to the attacker's mining address. The payload then
uses
'cmdfile.commit' method to make the address change persistent.
2. The victim running the NiceHash Miner Excavator plugin
browses to the site
hosting the malicious JavaScript payload. The payload activates and
redirects
NiceHash Miner to send the mined coins to the attacker's mining
address.
3. By targetting a wide audience of users running NiceHash
Excavator Miner, the
attacker could acquire thousands of miners, resulting in huge
profits.
Vulnerabilities
---------------
1. CWE-20: Improper Input Validation
The root cause for the vulnerability is the lax input validation
of the Excavator
TCP API endpoint. The API will consume newline terminated lines
arriving to the
API endpoint and merely skip invalid lines. This enables the attack
to work via
regular HTTP requests, effectively enabling the Cross-Site Request
Forgery attack.
Vulnerable versions
-------------------
The following product versions are vulnerable:
- NiceHash Excavator plugin up to and including version 1.6.7c.
End user recommendations
------------------------
1. Upgrade to the NiceHash Miner 3.0.6.5 or later.
Credits
-------
The vulnerability was discovered by Harry Sintonen / F-Secure Consulting.
Timeline
--------
2021.03.28 discovered the vulnerability
2021.03.28 wrote a proof of concept exploit
2021.03.28 contacted NiceHash over
2021.03.28 wrote the first draft of this advisory
2021.03.28 sent the advisory to
2021.03.29 Excavator plugin 1.6.11a released. this version switched
to
HTTP JSON API (-wp 4000)
2021.04.02 reminded
the issue
2021.04.15 NiceHash Miner 3.0.6.5 released, fixing the
vulnerability
2021.05.14 public disclosure
