Database Link Security
You've probably heard about database link security. It's a useful tool for securing links between databases and making sure users can't accidentally change them. There are a few problems with database link security, and Oracleforensics will cover some fixes. But first, let's talk about its limitations. There are some obvious things that go wrong when you use it. Here are a few of them. Read on to learn how to secure database links.
Problems with database link security
The problem of unauthorized access to a database can be mitigated with the use of private or public database links. A private database link only allows the user of the local database to access it. A public database link, on the other hand, allows anyone to access the remote database, even if the user has minimal privileges. In any case, you should always encrypt the database link connection, both during transit and at the point of connection, and limit access to database links to only authorized users.
The use of database links is a common security concern. Public database links are meant to be open to all users, and should never be used without authentication. Shared PUBLIC DB-Link with authentication is another option. In this case, the shared PUBLIC DB-Link is a single network connection that is shared by multiple users. This option is only available in multi-threaded servers. If you need to share a database link, you can use a shared server.
Another problem with database link security is that users can break the link by changing the user's password. Using an account with a low privilege level creates a security risk because low-privilege users can easily access a database link. The reason for this is that there is no single database that has the complete picture of the data that's stored in it. The user's password is stored as a hash, which can be easily decrypted.
Another problem with database link security is that the user's actual identity is not revealed. The attributes creatorsName and modifiersName contain the name of an administrative user. Administrators can also add their own names to database links, including the name of a user account that has proxied authorization rights on the remote server. The cn=proxy_admin,cn=config user is an administrative user that has read-only access to the data on the remote server.
When the database link is not trusted, it fails to execute an SQL statement. It returns an error message. In such a case, the SQL statement cannot be executed. If it fails, the server is unable to find the database. To fix the problem, you need to use database security certificates. There are a few different types of security certificates that can be used, and the list is long. There are also security certificates that can be purchased. You can also choose to purchase licenses for your site.
Another common problem with database link security is the use of passwords. Insecure passwords can cause data breaches. Moreover, passwords can be misinterpreted by malicious users. If your users have multiple passwords, it can be difficult to identify them. It's essential to know how to prevent password theft by using password-protected database links. And make sure to update your passwords regularly. In addition, make sure to check the database security settings for your application.
Fixes for database link security
DBLinks are connections between two databases, which enable one to execute queries in another. The originating database uses the username and password of the remote destination database to execute queries. As a result, the originating database gains access to the privileges of the remote database. Private database links are available only to the owner, while public database links can be accessed by any user, including those with low privileges. However, to prevent unauthorized access to database links, DBLink connections must be encrypted during transit and originate from restricted IP addresses.
If a database link is shared with another user, the security context of this connection can change. However, in general, a database link will always be created and used with the security context of the connected user and current user at the local database. This means that if a database link is shared between two different databases, then the connected user can easily change the user credentials and access the remote database. To prevent this situation, make sure that database link security is properly configured in your application.
Another way to ensure the security of database links is to use SCN levels higher than 1024. Unpatched versions of Magento may experience issues with database links if they don't support higher SCN levels. In this case, you can try to update your database. However, older unpatched versions of Magento may experience problems with database links after June 23rd 2019.
Public database links are available to any user with a DBA role. If your application uses public database links, it might leak SQL injections. Because the database links are publicly available, security cannot depend on the other links in the chain. Fortunately, there are tools like TOAD and SQL Developer that can show you whether a database link is public or private. They also make it visible for users with privileged roles. Using a database link with a private connection can help you avoid security issues in that case.
However, shared database links don't work in all cases. The problem arises when a user uses more than one database link on the same network. In these cases, a single user may need as many as 10 network connections to access a remote server. This is an obvious issue and should be addressed as soon as possible. You should avoid using shared database links. Lastly, make sure you protect your data by installing anti-malware software.
The first way to avoid data theft is to implement a secure database link. Make sure that the database link passwords are synchronized between the two databases. For example, if a database link is made available to users of a remote server, the passwords of both databases must be identical. Similarly, if you want to use a database link in the same server, you need to ensure that it is not accessible by external users.
Limitations of database link security
A database link is a method of storing data between two databases. There are two types of database links: shared database links and non-shared database link. A shared database link is created by a shared server process, whereas a non-shared database link is created by a local dispatcher and requires context switches to send data through the dispatcher. Shared database links allow users to access an object in a remote database without having an account on that database.
There are a number of limitations to the security of database links. For example, database links connect to database users, and each user should be unique. A database link can be broken simply by changing the password of the user who created it. Whenever possible, database consolidators should use a new user for each database link to prevent issues down the road. If a public resource has to access a database, the database link can be broken by changing the password of the user that owns it.
In addition to being a weak form of security, database links are also vulnerable to abuse. Some of the most common mistakes users make with database links are related to the name of the database. Changing the name of a database link is difficult, and often involves revisiting the code. A more sensible approach would be to use a general service name for the link, such as hr_staff, orcl, etc.
Fortunately, many modern databases are able to support multi-level security for their databases. A database link can be used in the same way a local database can be used for local data. This feature allows users to perform operations on multiple remote databases without requiring them to use credentials that would be stored in the local database. The security of a database link depends on several factors, including the database password, operating system, network authentication service, and the remote database's acceptance of remote authentication.
Another limitation of shared database link security is that it is one-way. If a client is connected to a local database A, that client can access the remote database B. However, the same client cannot access the data in the local database A. Therefore, local users of database B must create the link in the data dictionary of database B. As you can see, database link security is very different in both cases. You need to be very careful about the security of a shared database link.
Another limitation of database link security is that it is not evaluated for access control. This means that database links cannot see the content of a remote entry during access control evaluation. However, if you use the nsCheckLocalACI attribute, this limitation can be overcome. Nevertheless, it is not recommended to use this feature unless it is absolutely necessary. You should instead use a global database link, which allows you to manage multiple databases with one administrator.