I was wondering if anybody can show me way to be able to create read file permissions for my java applet.
The exact exception I receive is
java.security.AccessControlException: access denied(java.io.FilePermission filename.pdf write)
I've put f.setReadable and f.setWriteable where f is the file and nothing. A little help please.
There's security limits on what an unsigned applet can do, and one of the things it can't do is access the local filesystem (see here for a full list). You have several options:
Sign your applet. If a user then runs your applet it won't run with any security restrictions. However, signing your applet with a trusted certificate costs at least $100 a year, and if you self-sign then nobody is going to trust your applet. And even if you do sign with a trusted certificate the user might decide not to run it.
Set up your applet with a JNLP file. This will let your applet use the javax.jnlp package. You can then use the FileOpenService and FileSaveService to ask the user to let you read/write one particular file. Alternatively, you can use the PersistenceService to store a small amount of data persistently within the browser.
Related
I am loading applet in the browser and I want to delete the cache at the start of an applet. The applet stores its cache information in C:\Users\<username>\AppData\LocalLow\Sun\Java\Deployment\cache. I did not find much information on how to delete the cache using java program. And I referred some link that said to use Config.getCacheDirectory() but no luck on that too.
Please let me know if you have any other approach to delete the cache.
You can't access the file system of the client through an applet. Not unless the applet is signed with a certificate by a trusted authority.
I've made a Java applet and I self signed it before, but due to security changes in recent Java updates, self signing no longer gives the applet the necessary permissions.
I need the applet to be able to read the local file system to use images and to be able to connect to a MYSQL database.
The applet used to work with the database when I self signed it, but not anymore.
In addition, many unknown users will be using the applet, so I won't have control over their machines.
Where can I get my applet professionally signed and if possible, is there another way to self sign that will make the applet work?
Purchase a certificate from any reputable certificate authority. Use that to sign your code. List of CAs
Or, some companies also do this: Sign the jars themselves, but pre-populate the JDK trust store with your (self created) CA cert. If you have control over the JRE that is installed on all user machines, you can place your certificate in JRE/lib/security/cacerts so that is trusted ahead of time.
update: This page (Java Control Panel Documentation) describes what type of signature is required for various client side security level settings:
As long as the applet 'phones home' to the DB & this demo. of the JNLP API file services1 works for the problem machines you should be set to go for a Plug-In 2 JRE (1.6.0_10+) JRE. And if the client has less than that, they should seriously look to update. The Deployment Toolkit Script can assist with that.
It is relevant in that:
It uses a self signed certificate
It allows a sand-boxed app. to read/write to the local file system.
An applet launched using JWS has access to the API.
This should only be considered a work-around. The correct way to solve the problem is to heed the advice offered to get a certified code certificate. Oracle seems to be heading towards making it so that unsigned or self-signed code will not just be sand-boxed, but entirely forbidden (& that is for the best).
As an aside re. DB access: For the protection of the DB. The applet should be forced to go through a 'public interface' (via the site that hosts the applet). Do not give the applet direct access to the DB. Otherwise hackers also have direct DB access.
I've made an applet, which requires access to the user's home catalog. First I signed it with a self signed certificate and everything works if the user accepts the applet security prompt.
The problem is that the user's who are going to use the applet from their intranet, have limited permissions on their computers. Therefore, if the user accepts the security prompt and selects "Don't ask again", the modifications (wherever they are stored) are not written to their computers. Rather, the applet will ask for permissions the next time again, and the customer does not want to be prompted every time.
I've tried to overcome this problem by not signing the applet and modifying a policy file instead:
grant codeBase "http://server:port/app/-" {
permission java.io.FilePermission "${user.home}/-", "read, write, delete";
permission java.util.PropertyPermission "user.home", "read";
};
but the applet is prompting for permission every time now even if I select "Don't ask again" and I have administrative rights myself on my computer.
If I could somehow get it to work using policy files it would be easy to make a script to write the policy files on all the hundreds of computers that will use it.
I guess the question is, can policy files be used in such a way that the users are not prompted at all? The code is trusted by the users anyway so they are fine by having the code run everything that is necessary.
What is the purpose of having policy files if the users are prompted anyway? Then it will be as bad as having the self signed applet asking for permission every time.
Any help or tips are appreciated!
EDIT:
I exported the self signed certificate using the keytool, and imported it on a virtual machine using the keytool into the trusted certs. The applet still asks for permission to run.
I also tried the following:
Select "Always allow", now the certificate is saved in "...Application Data\Sun\Java\Deployment\security\trusted.certs"
Export certificate using Control Panel->Java->Security->Manage Certificates->Export
Delete the certificate Control Panel->Java->Security->Manage Certificates->Remove
Import the previously exported certificate using the keytool
The applet still asks for permission, even if the certificate should be the same.
However, if I open the trusted.cert in notepad++ I can see that some binary characters differs if the certificate was automatically installed by selecting "Always Allow" compared to importing the certificate using the keytool.
The only option I found to work is to select "Always Allow" on one machine and copy the whole trusted.cert file and replace the trusted.cert file on the target machine. That way it believes the user has already chosen "Always Allow".
This does not seem like a good solution.
Edit2:
Copying the whole trusted.cert file only worked in my virtual machine. Others who used my trusted.cert could not run the applet without giving it permission first. Perhaps Java is not up for the task, maybe flash is not that restricted.
My client wants to use an applet to do drag and drop file transfers from the browser. We have everything working for the most part, but the .java.policy file granting the applet file system access needs to be uploaded to every client in order for the applet to have permission to read/write to the file system.
My technical counterpart at the client has just done some research and wants me to look into the java deployment toolkit (a js library that takes care of deployment instead of using html tags). He wants me to see if I can configure the applet to use a policy file requested from a URL. I haven't been able to find how to do this, which is what I expected, since I think it would be a terrible security risk.
The trouble is that they need to be able to grant the applet read/write file system access, but I feel that requesting a policy file from a URL is a bad idea and I need help explaining why.
So that's my question: is requesting a .java.policy file from a URL even possible? If so, isn't that a terrible security risk?
So that's my question: is requesting a .java.policy file from a URL even possible?
Yes it is, but not in any way that is practical. The thing is:
The policy file needs to be in a certain location on the local file system, in order to work.
Any Java app. or applet would need trust to place it there, or even find out where the right location is.
A Java app. needs extended permissions to be able to import the policy file to where it will have an affect.
If a Java app. has the permissions to insert the policy file, it is already trusted.
If so, isn't that a terrible security risk?
Yes, it would be.
If this applet needs trust, digitally sign it.
Addendum
See Java 7 Update 21 Security Improvements in Detail for more info. on the ever tightening Java security environment.
It is apparently planned to have a future JRE default to maximum security. That would mean that by default, only classes in a Jar, digitally signed by a certificate issued by a Certification Authority (e.g. Comodo $180/year, Thawte $300/year) would ever run. Everything else would be rejected.
I recently stumbled across a problem when starting my application via JNLP. I now narrowed it down to a java.security.AccessControlException, which denies me to shut down my ExecuterService.
So, I did some reading and found out that I'll need the permission (modifyThread) to successfully shut down the service. I also found out that I should use the <security>-tag (in the JNLP-file) to request it, but I'm a little confused about how.
The documentation of the tag says:
[...] If the all-permissions element is specified, the application
will have full access to the client machine and local network. If an
application requests full access, then all JAR files must be
signed. The user will be prompted [...]
From reading this it seems to me, that I can choose to either get all or no permissions... which seems like a confusing Implementation. Because I only need the one to shutdown my service.
I also read this article, telling me that I should not request all permissions, because I would then open up the users computer for malicious code.
So, is there a way to specify that I only need the specific permission (modifyThread) and I therefor don't need to sign my jar? Or will I have to go with the "sign my jar and request everything"-approach?
..will I have to go with the "sign my jar and request everything"-approach?
Yes. JWS permissions come in 3 levels1, the only one where modifying threads is permitted, is all-permissions.
1) JWS security levels
Sand-boxed. Provides a very limited environment. Access to things like printers and the local file-system is only permitted using the JNLP API services, which provide more limited forms of File after prompting the user. Come with window banners. Can only communicate with own server.
j2ee-application-client-permissions - provide those JNLP API services unprompted (after the user accepts the digitally signed code) removes the window banners.
all-permissions - pretty much anything, including replacing the existing security manager (yes, even 'all permissions' code gets a security manager in JWS - it is just very lenient).
Also chase the links from the JNLP & JWS pages. I can personally recommend those summaries & links.