cis-nginx-v300-2-4-4

DevOps & Security

Ensure send_timeout is set to 10 seconds or less, but not 0 (Manual)

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CIS 2.4.4 — Ensure send_timeout is set to 10 seconds or less, but not 0

Profile Applicability

Level 1 - Webserver
Level 1 - Proxy
Level 1 - Loadbalancer

Description

The send_timeout directive sets a timeout for transmitting a response to the client between two successive write operations.

Rationale

Setting the send_timeout directive on the server side helps mitigate slow HTTP denial of service attacks by ensuring write operations taking up large amounts of time are closed.

Impact

Setting the send_timeout to a low value may impact clients with slow connections or applications that stream large responses.

Audit Procedure

To check the current setting for the send_timeout directive, issue the below command. You should also manually check your nginx configuration for include statements that may be located outside the /etc/nginx directory. If none of these are present, the value is set at the default.

grep -ir send_timeout /etc/nginx

The output of the command should be similar to the following:

send_timeout  10;

Remediation

Find the HTTP or server block of your nginx configuration, and add the send_timeout directive. Set it to 10 seconds or less, but not 0.

send_timeout    10;

Default Value

send_timeout 60s;

References

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	16.1 Establish and Maintain a Secure Application Development Process	N	Y	Y
v7	18.1 Establish Secure Coding Practices	N	Y	Y

MITRE ATT&CK Mappings

Tactic	Technique
Impact	T1499 - Endpoint Denial of Service

Profile

Level 1 - Webserver
Level 1 - Proxy
Level 1 - Loadbalancer