this post was submitted on 24 Apr 2024
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Security Operations

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submitted 6 months ago* (last edited 6 months ago) by lettruthout to c/secops
 

The NGINX access.log of my VPS is showing a curiosity.

Instead of a simple request like this...

"GET / HTTP/1.1"

...regular requests are coming in that look like this

"\x03\x00\x00\x13\x0E\xE0\x00\x00\x00\x00\x00\x01\x00\x08\x00\x03\x00\x00\x00"

Is this some kind of hack attempt?

Here's an example of a full line from the log...

15.204.204.182 - - [24/Apr/2024:15:59:47 +0000] "\x03\x00\x00\x13\x0E\xE0\x00\x00\x00\x00\x00\x01\x00\x08\x00\x03\x00\x00\x00" 400 166 "-" "-"

EDIT: For what it might be worth, most of these requests come in singularly, from different IP addresses. Once (that I've noticed) repeated attempts came in quickly from one specific IP.

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[–] breadsmasher 3 points 6 months ago* (last edited 6 months ago)

Might be misconfigured SSL? Or a scan?

https://www.joshwieder.net/2015/11/an-explanation-of-webserver-logs-that.html?m=1

The error indicates an attempt to scan OpenSSL for the SSLv3 POODLE vulnerability. No need to panic - getting scanned is an everyday occurrence for web server administrators, and hopefully your server is already long since patched for POODLE and disabled SSLv3 connections entirely. Furthermore, many of the servers scanning the internet making these connections are researchers - the example I provided above referencing the IP address 184.105.139.68 is one such example, and belongs to a group called "The Shadowserver Foundation" that reviews the internet for vulnerabilities and publishes trends in their findings.

[–] slazer2au 2 points 6 months ago (1 children)

Looks like a generic obfuscation code.

[–] lettruthout 1 points 6 months ago (1 children)

So a form of request smuggling? If that's a string of hex values, I'm not seeing how they would decode to anything useful.

[–] theit8514 2 points 6 months ago

The log translated binary data received to hex escape codes so that your log is not dangerous when you cat it. This could be misconfigured port or some sort of scan (e.g. Someone is trying to https to your http port and it wants to negotiate a SSL/TLS session). The IP listed is a OVH server and appears to be running IIS on http.