Posts Tagged ‘nss’

Dump Firefox passwords using Python (and libnss)

Friday, February 3rd, 2012

I was travelling and I didn’t have my Firefox instance on my laptop. I wanted, however, access some websites and the passwords were stored safely in my Firefox profile at home. Needless to say that I don’t upload my passwords to someone’s server. Back in the day, when I first encountered that problem, there were only ugly options to run the server yourself. Either some PHP garbage or worse: some Java Webapp. I only have so many gigabytes of RAM so I didn’t go that route. FWIW: Now you have a nice Python webapp and it might be interesting to set that up at some stage.

I could have copied the profile to my laptop and then ran Firefox with that profile. But as I use Zotero my profile is really big. And it sounds quite insane, because I only want to get hold of my 20 byte password, and not copy 200MB for that.

Another option might have been to run the Firefox remotely and do X-forwarding to my laptop. But that’d be crucially slow and I thought that I was suffering enough already.

So. I wanted to extract the passwords from the Firefox profile at home. It’s my data after all, right? Turns out, that Firefox (and Thunderbird for that matter) store their passwords encryptedly in a SQLite database. So the database itself is not necessarily encrypted, but the contained data. Turns out later, that you can as well encrypt the database (to then store encrypted passwords).

So a sample line in that database looks like this:

$ sqlite3 signons.sqlite 
SQLite version 3.7.11 2012-03-20 11:35:50
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> .schema
CREATE TABLE moz_deleted_logins (id                  INTEGER PRIMARY KEY,guid                TEXT,timeDeleted         INTEGER);
CREATE TABLE moz_disabledHosts (id                 INTEGER PRIMARY KEY,hostname           TEXT UNIQUE ON CONFLICT REPLACE);
CREATE TABLE moz_logins (id                 INTEGER PRIMARY KEY,hostname           TEXT NOT NULL,httpRealm          TEXT,formSubmitURL      TEXT,usernameField      TEXT NOT NULL,passwordField      TEXT NOT NULL,encryptedUsername  TEXT NOT NULL,encryptedPassword  TEXT NOT NULL,guid               TEXT,encType            INTEGER, timeCreated INTEGER, timeLastUsed INTEGER, timePasswordChanged INTEGER, timesUsed INTEGER);
CREATE INDEX moz_logins_encType_index ON moz_logins(encType);
...
...
sqlite> SELECT * FROM moz_logins LIMIT 2;
1|https://nonpublic.foo.bar|Non-Pulic Wiki||||MDoEEPgAAAAAAAAAAAAAAAAAAAEwFAYIKoZIhvcNAwcECFKoZIhvcNAwcECFKoZIhvcNAwcECF|MDIEEPgAAAAAAAAAAAAAACJ75YchXUCAAAAAEwFAYIKoZIhvcNAwcE==|{4711r2d2-2342-4711-6f00b4r6g}|1|1319297071173|1348944692451|1319297071173|6
2|https://orga.bar.foo|ToplevelAuth||||MDoEEPgAAAAAAAAAAAAAAAAAAAEwFAYIKoZIhvcNAwcECIy5HFAYIKoZIhtnRFAYIKoZIh|MDoEEPgAAAAAAAAAAAAAAAAAAAEwFAYIKoZIhvFAYIKoZIhBD6PFAYIKoZIh|{45abc67852-4222-45cc-dcc1-729ccc91ceee}|1|1319297071173|1319297071173|1319297071173|1
sqlite> 

You see the columns you’d more or less expect but you cannot make sense out of the actual data.

If I read correctly, some form of 3DES is used to protect the data. But I couldn’t find out enough to decrypt it myself. So my idea then was to reuse the actual libraries that Firefox uses to read data from the database.

I first tried to find examples in the Firefox code and found pwdecrypt. And I even got it built after a couple of hours wrestling with the build system. It’s not fun. You might want to try to get hold of a binary from your distribution.

So my initial attempt was to call out to that binary and parse its output. That worked well enough, but was slow. Also not really elegant and you might not have or not be able to build the pwdecrypt program. Also, it’s a bit stupid to use something different than the actual Firefox. I mean, the code doing the necessary operations is already on your harddisk, so it seems much smarter to reuse that.

Turns out, there is ffpwdcracker to decrypt passwords using libnss. It’s not too ugly using Python’s ctypes. So that’s a way to go. And in fact, it works well enough, after cleaning up loads of things.

Example output of the session is here:


$ python firefox_passwd.py | head
FirefoxSite(id=1, hostname=u'https://nonpublic.foo.bar', httpRealm=u'Non-Pulic Wiki', formSubmitURL=None, usernameField=u'', passwordField=u'', encryptedUsername=u'MDoEEPgAAAAAAAAAAAAAAAAAAAEwFAYIKoZIhvcNAwcECFKoZIhvcNAwcECFKoZIhvcNAwcECF', encryptedPassword=u'MDIEEPgAAAAAAAAAAAAAACJ75YchXUCAAAAAEwFAYIKoZIhvcNAwcE==', guid=u'{4711r2d2-2342-4711-6f00b4r6g}', encType=1, plain_username='wikiuser', plain_password='mypass')
FirefoxSite(id=2, hostname=u'https://orga.bar.foo', httpRealm=u'ToplevelAuth', formSubmitURL=None, usernameField=u'', passwordField=u'', encryptedUsername=u'MDoEEPgAAAAAAAAAAAAAAAAAAAEwFAYIKoZIhvcNAwcECIy5HFAYIKoZIhtnRFAYIKoZIh', encryptedPassword=u'MDoEEPgAAAAAAAAAAAAAAAAAAAEwFAYIKoZIhvFAYIKoZIhBD6PFAYIKoZIh', guid=u'{45abc67852-4222-45cc-dcc1-729ccc91ceee}', encType=1, plain_username='suspect', plain_password='susicious')

The file is here: https://hg.cryptobitch.de/firefox-passwords/

It has also been extended to work with Thunderbird and, the bigger problem, with encrypted databases. I couldn’t really find out, how that works. I read some code, especially the above mentioned pwdecrypt program, but couldn’t reimplement it, because I couldn’t find the functions used in the libraries I had. At some stage, I just explained the problem to a friend of mine and while explaining and documenting, which things didn’t work, I accidentally found a solution \o/ So now you can also recover your Firefox passwords from an encrypted storage.