Why Cached mail is not encrypted on the N900 device??? - Page 2 - maemo.org

lma | # 11 | 2010-10-29, 07:35 | Report

Originally Posted by Pluto View Post

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

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.

Originally Posted by

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

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

ossipena | # 12 | 2010-10-29, 07:39 | Report

Originally Posted by Pluto View Post

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.

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

Code:

sudo gainroot

?

buchanmilne | # 13 | 2010-10-29, 07:51 | Report

Originally Posted by Pluto View Post

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.

What key should it use to encrypt messages?

Originally Posted by

This is a major security issue since the application does not comply with industry security standards.

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.

Originally Posted by

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.

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

Originally Posted by

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

Should we report this as a bug?

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)

lma | # 14 | 2010-10-29, 07:54 | Report

Originally Posted by ossipena View Post

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

Code:

sudo gainroot

?

If you think root privileges can bypass everything, then

Code:

-----BEGIN PGP MESSAGE-----
Version: GnuPG v1.4.10 (GNU/Linux)

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zy2OxlzUjhmi6UmNaozEFH2DiLL5Jt4hv5iJXSk5kQacPF6BfWyMzyFKGKiYwqnS
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Ow4sNv0QqAb0OtX83A9bzZ7IOSAFCY9wCqvvsk/o/xKnE5s=
=ECnd
-----END PGP MESSAGE-----

juise- | # 15 | 2010-10-29, 08:18 | Report

Originally Posted by lma View Post

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.

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.

Last edited by juise-; 2010-10-29 at 08:22.

lma | # 16 | 2010-10-29, 08:31 | Report

Originally Posted by juise- View Post

The password could be asked every time the app is started for example (and that would mean no automatic mail fetching in background).

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 :-(

Originally Posted by

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.

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.

juise- | # 17 | 2010-10-29, 08:46 | Report

Originally Posted by lma View Post

That would mean storing the key in RAM, from where it's trivial to retrieve it.

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?

Originally Posted by lma View Post

Besides, the email app is autostarted at boot time, even if you don't want it and don't even have any accounts configured :-(

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

Originally Posted by lma View Post

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.

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

Originally Posted by juise-

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.

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).

Last edited by juise-; 2010-10-29 at 09:08.

ossipena | # 18 | 2010-10-29, 09:03 | Report

Originally Posted by lma View Post

If you think root privileges can bypass everything, then

Code:

-----BEGIN PGP MESSAGE-----
Version: GnuPG v1.4.10 (GNU/Linux)

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=ECnd
-----END PGP MESSAGE-----

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.

Last edited by ossipena; 2010-10-29 at 09:05.

lma | # 19 | 2010-10-29, 09:16 | Report

Originally Posted by juise- View Post

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?

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.

Originally Posted by

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

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

Originally Posted by

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

Originally Posted by

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.

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.

dchky | # 20 | 2010-10-29, 09:22 | Report

Originally Posted by Pluto View Post

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.

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...

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