Why Cached mail is not encrypted on the N900 device???
 

I surprisingly noticed today as I “ssh” into the device to find out that all cached sent, received & draft mail is stored as plain text on the device. This includes a summary information file that includes all headers of emails (sender, recipients, subject, etc).

If you check the directory “/home/user/.modest/cache/mail/imap/” you will find all your email accounts subfolders, if you navigate to any of those you will find that all the information is stored in plain text. There are also subfolders within each email account. For example if you go to the INBOX subfolder you will find that emails are stored in plain text.

This is a major security issue if the device is lost or stolen.

Is there an encryption option somewhere that I haven’t noticed or is this simply the lack of encryption within the device?

Re: Why Cached mail is not encrypted on the N900 device???
 

so what you are saying is that a thief would look for your emails in home/user/.modest/cache/mail/imap/ ?

why couldn't he just use the email app?

... what is the point of encryption if the e-mail app is unprotected. could you please explain. =D

Re: Why Cached mail is not encrypted on the N900 device???
 

We already went over a similar thing

http://talk.maemo.org/showthread.php?t=41164

Re: Why Cached mail is not encrypted on the N900 device???
 

Dante, I don't store the email passwords on the device (email setup), so the thief won't be able to log into the account, however emails are being stored as plain text which is a huge security issue.

Re: Why Cached mail is not encrypted on the N900 device???
 

Yes, thanks I had seen this, but it is talking about usernames/passwords being stored in plain text which is not an issue for me since I never store passwords on the device.

I am concerned that email messages are stored in plain text, which is a big problem.

Re: Why Cached mail is not encrypted on the N900 device???
 

Encrypt your homedir, search for bug report about this and if there isn't one file a new one. This was also discussed in the Brainstorm forums already, btw.

Re: Why Cached mail is not encrypted on the N900 device???
 

I am pretty sure we have SOME program available in the repos for mounting/creating encrypted disks/volumes. I would just delete all cached emails if paranoid enough - but I can see why you'd want encryption.

However, I'm pretty sure even if you encrypt the emails using the available tools, the N900's email app would take some hacking to make it capable of opening and saving them in that encrypted volume.

Perhaps turn to one of the community email apps that are being actively developed, and see if you can get them to integrate that with email encryption upport?

Re: Why Cached mail is not encrypted on the N900 device???
 

because this is not an E-series device?

Re: Why Cached mail is not encrypted on the N900 device???
 

Want encrypted emails? Get a Blackberry :)

Re: Why Cached mail is not encrypted on the N900 device???
 

Thanks for all the replies. I guess the issue is, in this case, is with the actual native mail client on the N900. It does not encrypt stored messages. This is a major security issue since the application does not comply with industry security standards. I was actually very surprised.

So the correct solution is for the native email client to store this info encrypted.

I have done some other research and apparently there are a number of apps both native and/or developed that stores info like usernames, passwords, chat messages, SMS, etc, in plain text.

For the time being does anyone know of a secure email client?

Should we report this as a bug?

Re: Why Cached mail is not encrypted on the N900 device???
 

And then what? Should it prompt for the decryption key every time you access a stored message? Anything else would mean the key is stored somewhere (even if it's just in RAM) which defeats the purpose.

You could use claws-mail and PGP for sensitive messages.

Re: Why Cached mail is not encrypted on the N900 device???
 

what is the point complying to industry standards when you can bypass everything with one single
?

Re: Why Cached mail is not encrypted on the N900 device???
 

What key should it use to encrypt messages?

Could you provide a reference to these "security standards"? Most PC-based mail clients don't encrypt cached mail by default, in the absence of FDE, laptops are usually by default as vulnerable.

So, maybe the problem isn't just the email client.

First, one should come up with a standard the device should adhere to, or reference one.

Second, we could probably run through some concepts of how this could be implemented to support a standard while not making the device almost impossible to use or losing existing features (such as ability to access "MyDocs" from PCs without requiring software that might not be present on most PCs)

Re: Why Cached mail is not encrypted on the N900 device???
 

If you think root privileges can bypass everything, then

Re: Why Cached mail is not encrypted on the N900 device???
 

That would be the only proper solution, however the "every time" part can be relaxed a bit. The password could be asked every time the app is started for example (and that would mean no automatic mail fetching in background).

Easiest thing for an user to do is to set up home dir (or full disk) encryption. Both should be within reach, however will require some hacking. Strict device lock policy is also necessary, so that an average attacker is forced to clear the RAM (and the enc. key) as his first move.

For OP, if you want security standards compliance, go with a security standards certified device. N900 is not one, and won't become one with a software update. I'm quite sure e-mail local storage isn't the only area where security fails.

Re: Why Cached mail is not encrypted on the N900 device???
 

That would mean storing the key in RAM, from where it's trivial to retrieve it. Besides, the email app is autostarted at boot time, even if you don't want it and don't even have any accounts configured :-(

But the encrypted block device/filesystem would be mounted (and thus accessible as plaintext) while the device is on. The only protection it would add would be in case the thief rebooted the device before trying to read the messages.

Re: Why Cached mail is not encrypted on the N900 device???
 

I challenge you to retrieve something from my device's RAM, right now!

No, really, how do you do it without access to the device?

(Edit: OK, we're probably talking about different things, I meant the naive way where the GUI == app)

And how do you do it with access to a LOCKED device?

It's not about if it's running or not, it's about if it's keeping key material in RAM. Two different things.

You only quoted half of that block, and it also seems that you only read half of it. Here's the second half again:

Edit:
Trying to make it more clear, that my assumption was that either:
(a) The attacker has access to device that has no key material in RAM (i.e. the e-mail app was closed before he got access).
(b) The attacker has access to device that has key material in RAM, but that is locked (the HDE/FDE case WITH automatic locking).

Re: Why Cached mail is not encrypted on the N900 device???
 

you completely missed my point. doesn't root have access to stuff millisecond before you start generating the encrypted data?

e: I mainly referred to the fact that giving physical access to someone might end things up in a way that there is a script running as root, grabbing data and uploading it to server x. even when you have million industry standards, things doesn't change a bit.

Re: Why Cached mail is not encrypted on the N900 device???
 

The same way you would retrieve plain-text emails without physical access or from a locked device (which may include "no way"). My point is that encrypting the stored messages doesn't really add any extra security unless it's implemented in a way that's too inconvenient for most people to use.

That was in response to the password being "asked every time the app is started".

I'm not sure what that means exactly - clearing the entire RAM would be equivalent to a reboot, no? Clearing just the keys is possible, but that would mean either asking for a passphrase after every unlock or using the (really weak) device lock code to protect that at which point you might just as well not bother. Having a "real" login that allows strong alpha/numeric/symbolic passwords instead would help of course.

In Harmattan, with access to the hardware TPM (but only in "closed" mode), the situation will be different but for Maemo as it stands I don't see any good solutions.

Re: Why Cached mail is not encrypted on the N900 device???
 

If you are worried about security - symlink your mail store to a truecrypt partition that you manually mount any time you want to interact with Modest or whatever your mail user agent happens to be.

This isn't the huge security flaw that you feel it is. Really, it's not.

There comes a point where you need to decrypt your email to read it obviously, and to do this you need a key that has to be difficult to brute force - so ask yourself, are you really going to type in 64+ characters or whatever your pass phrase happens to be, every time you want email? It's the only way - otherwise you leave yourself open to key recovery via RAM, swap, or storage.

It's much easier to beef up your physical security than worry so much about email.

Alternatively you could just go web based and keep your mail server locked in a concrete box in your basement...

Re: Why Cached mail is not encrypted on the N900 device???
 

What? Why do you say so? I thought if you wanted to reset the lock code all the data would be erased.

Re: Why Cached mail is not encrypted on the N900 device???
 

If you were an interesting target any half decent 3 letter agency is going to be monitoring the message recipients along with traffic analysis that soaks up your contact associations many levels deep - as well as all their chatter. If you were a really interesting target, then someone will pick through your trash and watch everything you do, everything your associates do, their trash as well.

You might be great at keeping secrets, but trust me when I say the vast majority of humans are terrible at it.

I'm an ex military scope goat and secret 3 letter agency drone, even when people are trained to keep compartmented TS stuff secret, we are still human on the inside and have the same failings.

Encryption is only a tiny part of the bigger picture - if you haven't secured the rest of the jigsaw you might as well not encrypt anything.

Re: Why Cached mail is not encrypted on the N900 device???
 

As an encryption passphrase, a 5-8 digit long numeric-only string is useless (it can be brute-forced easily).

That's a different discussion, but no. There are many threads here describing how to discover/reset the lock code, just search for them.

Re: Why Cached mail is not encrypted on the N900 device???
 

Sure, but the threat model we are discussing here is rather more modest. Most people just want to keep their private data private when they lose their device, leave it unattended for 5 minutes etc. People who worry about 3 letter agencies probably shouldn't be using a phone to store sensitive data in the first place ;-)

Re: Why Cached mail is not encrypted on the N900 device???
 

Here's some entropy counts for different password lengths, assuming [0-9A-Za-z] 62 character alphabet, and brute force times (assuming 1ns/attempt, which is quite fast unless you go distributed):

8 characters: 47 bits, 1 day
10 characters: 59 bits, 4857 days
12 characters: 71 bits, 18670525 days =~ 50000 years.
14 characters: 83 bits, ~20 million years.

So, strong passwords don't have to be inpractically long, provided that the password is not guessable.

This still faces the same issue of having to type your password in every time. Unless you store the password on the device...

Yes, most passwords start to fail when the secret keeper is pointed with a weapon.

Re: Why Cached mail is not encrypted on the N900 device???
 

Right you are :-)

From a more modest perspective I think a better option would be SMSCON - as soon as you notice your phone is lost, send it a kill signal - have the kill signal also trigger on things a thief is likely to do - swapping sim card, opening up certain applications and so on.

Re: Why Cached mail is not encrypted on the N900 device???
 

I think we might be straying away from the real issue. The issue is not whether the N900 is a secure device or not, the issue is with applications themselves. It doesn’t matter whether you run the app on a mobile computer, a smart phone, a laptop or a PC, what matters is the app shouldn’t be storing or caching such sensitive information in plain text, specially without the user knowledge or any control to disable/enable.

I am not talking here about a hacker getting a hold of the device and try to break any sort of encryption, that’s a different story all together, I am talking about ordinary users who can simply use any text viewer and instantly have access to sensitive info without any computer savvy experience. It doesn’t matter what device this stuff is on.

Bottom line is apps should not be storing sensitive info in plain text. It is a no no, plain and simple and is a security guideline in any development framework.

Re: Why Cached mail is not encrypted on the N900 device???
 

The N900 does not have the security Level of a symbian s60 device - without "hacks" like truecrypt etc. Plaint Text Passwords are a bad joke in every way. Of you want security, you have it to make it yourself - on your n900 :p

But allmost every Mail-Client will store Mails in 0815-Text files - this is normal: NORMAL.

Re: Why Cached mail is not encrypted on the N900 device???
 

Please, don't make us throw again the same tired arguments against plain text passwords again and read the thread I quoted on the previous page.

Re: Why Cached mail is not encrypted on the N900 device???
 

Security Flaws can not be mentioned often enough. But it can also be a feature - so other people must reply to hundreds of mails in my own inbox :eek: