Category: Security

Whitelisting is one of the methods used to filter email and websites.
While the blacklisting method creates a list of dangerous users and websites, the whitelisting method creates a list of targets for which safety has been confirmed and excludes others. While it is possible to cut off dangerous objects completely, the contents of the list is arbitrary and limited to a part of safe objects, and it has the disadvantage of losing the user’s convenience.

AWS Firewall Manager is a security management service that makes it easy to configure and manage AWS WAF rules centrally across multiple customers’ accounts and applications. With the Firewall Manager, you can easily roll out the AWS WAF rules for the Application Load Balancer and Amazon CloudFront distributions across many AWS Organizations accounts. In addition, every time a new application is created, Firewall Manager makes it easy for new applications and resources to meet compliance with common security rules from day one. Now that you have a consistent set of firewall rules across the Application Load Balancer and Amazon CloudFront infrastructure, hierarchically build firewall rules, create security policies, and get single service to apply them.

1. Name web ACL
2. Create condition
– IP match condition
– String match condition, bad bot user agent
– SQL injection match condition, sqli checks
3. Create rules
4. Review and create

SAML is an abbreviation of Security Assertion Markup Language and is called “Samuru”.

SAML is a standard of authentication information developed by OASIS for authenticating users between different Internet domains. In other words, it refers to a rule protocol that exchanges user credentials.

Idp (= Identify Provider) is a system that provides authentication information. Without SAML, it is necessary to convert the format and format of information when the IdP and SP exchange information. You can save the trouble of that work.

Convenient improvement
With SSO, you can log in to different services with or user authentication. Because you do not need to authenticate each time, you can use the service comfortably.

Security improvements
Some users may be uneasy about the availability of many services with one authentication system. However, considering that most users use the same ID and password for all services and that only one login information needs to be managed securely, it can be said that there are security advantages as well.

Hashing is the generation of random numbers from certain data. The feature of this function is to output the same hashed value from any value, and it is impossible to derive the original data from the hashed value. The hash function is used for user authentication etc.

Know as a hash function, hash algorithms such as MD5 and SHA1 can now examine the output with brute force to get the original input.

$password = "password";
echo sha1($password) . "<br>";
echo md5($password) . "<br>";
echo hash('sha256', $password) . "<br>";

SELinux
SELinux(Security-Enhanced Linux) is a security extension module of the Linux kernel developed mainly by NSA(national security agency) in the united states. We will add the “secure OS” function to the Linux kernel. It is not the name of the distribution.

The biggest feature is that each process is designed to move with minimal authority considering the risk of root privilege.
The main functions are the following five. ref: security academy study meeting

1. MAC (Mandatory Access Control)
Only security administrator can set security

2. TE (Type Enforcement)
Access control for each process

3. Row Based Access Control(RBAC)
By assigning the administrative authority to the user, it is possible to avoid a mistake in operation with the conventional root

4. Domain transition
Allow only preset privilege escalation (deeply related to TE of 2)

5. Audit log
It is possible to logs of operations inside and outside the authority.

[vagrant@localhost tests]$ cat /etc/sysconfig/selinux
# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
#       enforcing - SELinux security policy is enforced.
#       permissive - SELinux prints warnings instead of enforcing.
#       disabled - SELinux is fully disabled.
SELINUX=disabled
# SELINUXTYPE= type of policy in use. Possible values are:
#       targeted - Only targeted network daemons are protected.
#       strict - Full SELinux protection.
SELINUXTYPE=targeted

disabled なので無効化されています。

getenforceでも見れるようです。

[vagrant@localhost tests]$ getenforce
Disabled

Permissions are represented by nine-character strings such as rwxr-xr-x and numeric values such as 755. The 9 character string consists of r(readable), w(writable), x(executable), and hyphen(-), which have the meanings.

The commonly used permission patterns are as follows.
644
normal HTML file etc. can read and write, but group members and others can only read.

666
files to be written by CGI script, etc. Both myself and group members and others can read and write.

755
Regular directories, commands, CGI script, etc. Everyone can read and execute, but write only oneself.

777
Directory for CGI scripts to create files. Anyone can do anything. Slightly dangerous on security.

Along with access restrictions with the host address, .htaccess can restrict access by user agent

SetEnvIfNoCase User-Agent "OpenVAS" ua_key=on

order allow,deny
allow from all
deny from env=ua_key
deny from #ip address

Deny port scan attacks from OpenVAS etc. for now.