LessPass – Jupiter Broadcasting

Unix Security Trifecta | TechSNAP 292

chris — Thu, 10 Nov 2016 08:48:15 +0000

RSS Feeds:

Become a supporter on Patreon:

Show Notes:

Unix Trifecta — Patch Your Shit

This week saw the trifecta, critical vulnerabilities in 3 of the most important and widely used server applications
CVE-2016-8610 – OpenSSL: A remote attacker who can initiate handshakes with an OpenSSL based server can cause the server to consume a lot of computation power with very little bandwidth usage, and may be able to use this technique in a leveraged Denial of Service attack.
The flaw is in the way OpenSSL handles “SSL Alerts”. The SSL alert protocol is a way to communicate problems within a SSL/TLS session. Due to improper handling of alert packets, OpenSSL would consume an excessive amount of CPU time processing undefined alert messages.
- CVE-2016-8864 – Bind: A remote attacker who could cause a server to make a query deliberately chosen to trigger the failed assertions could cause named(8) to stop, resulting in a Denial of Service condition to its clients.
- A defect in BIND’s handling of responses containing a DNAME answer could cause a resolver to exit after encountering an assertion failure in db.c or resolver.c.
- CVE-2016-8858 – OpenSSH: A remote attacker may be able to cause a SSH server to allocate an excessive amount of memory. Note that the default MaxStartups setting on FreeBSD will limit the effectiveness of this attack.
During the SSH handshake procedure, the client and server exchanges the supported encryption, MAC and compression algorithms along with other information to negotiate algorithms for initial key exchange, with a message named SSH_MSG_KEXINIT.
When processing the SSH_MSG_KEXINIT message, the server could allocate up to a few hundreds of megabytes of memory per each connection, before any authentication take place.
Patches for most OSes should be out by now, make sure you install them.

LessPass, an open source, storage-less password manager? Or is it…

“Managing your Internet passwords is not easy. You probably use a password manager to help you. The system is simple, the tool generates random passwords whenever you need them and save them into a file protected with a strong password. This system is very robust, you only need to remember one password to rule them all! Now you have a unique password for each site on the Internet.”
But, there are some shortcomings to that type of password manager
How do I synchronize this file on all my devices?
How do I access a password on my parents’ computer without installing my password manager?
How do I access a password on my phone, without any installed app?
To solve this, LessPass does it differently
“The system uses a pure function, i.e. a function that given the same parameters will always give the same result. In our case, given a login, a master password, a site and options it will returns a unique password”
“No need to save your passwords in an encrypted file. You just need to access the tool to recalculate a password from information that you know (mostly the login)”
There are some issues though.
- Some sites have different password complexity requirements, such as banks that limit the length of your password, or require a PIN that is all digits
- Some sites obviously do not hash passwords correctly, and do not allow some characters
- What if you want to, or need to, change your password?
LessPass has a solution for all of these, where you specify “password profile”, to remember the different complexity settings to generate the valid password
To manage to change the password, there is also a counter, that starts at 1, and you increment to get a different password.
Of course now, you have to remember: your login, your master password, the password complexity profile for each site, and how many times you have changed your password on that site
So, they have a “connected” version, that remembers each site, your login, the password profile, and your password change counter.
There are obviously some privacy concerns, and security concerns here.
How do you restrict access in the connected version, with a username and password? Is that password the same or different from your master password. Is your profile data encrypted per user?
Of course, being an open source project, there is the option to self-host, which eliminates a number of those concerns
“You can host your own LessPass database if you do not want to use the official one. The requirement for self-hosting is to have docker and docker-compose installed on your machine.”
The fact that the installation instructions are curl | bash (written the other way around, so that when you stick sudo in front of it it works), does raise some other concerns
This leaves a few problems:
- You can never change your master password, as it will effectively change all of your passwords
- It is still technically possible for someone to brute force your master password. Each attempt will require them to do the full PBKDF2 run, but 8192 rounds will take only a small fraction of a second, and it can be parallelized quite well. If someone does compromise your master password (via brute force, or with a keylogger, or whatever), they have access to all of your passwords, but worse, they even have access to your ‘new’ passwords, if you change your password, it just changes the ‘count’ parameter, so I could generate your next 10 gmail passwords and keep them for later.
- The key-derivation seems weak, 8192 rounds of PBKDF2 is likely not enough. LastPass uses 100,000 rounds for its server-side key-derivation. FreeBSD’s GELI disk encryption uses a number of rounds that will take approximately 2 seconds, which on modern machines is over 1 million rounds. The issue is that changing this number in the future will change all of your passwords. At a minimum, it should be part of the password profile, so you can select a different value for each site, so you can change the default for new sites in the future, and increase the strength of the password for one site by changing the password.
- LessPass cannot deal with SSO (Single Sign On). There are a number of sites for which I have the same password, because they all authenticate against the same LDAP database (or ActiveDirectory). LessPass ONLY allows you to use its derived passwords, which might not always work.
There are definitely some interesting aspects to LessPass, especially being able to self host, but, I don’t think I’ll be switching to it.

A very valuable vulnerability

It all started with a facebook post by Colin Percival: “I think I just accidentally exploited a “receive arbitrarily large amounts of money” security vulnerability. Oops.”
Colin Percival is a security and cryptography expert, and a former FreeBSD Security Officer
Colin’s day job is running Tarsnap – backups for the truly paranoid.
To accept payments for his business, he uses Stripe – a credit card processing service, which also allows him to accept bitcoins
“While I very firmly wear a white hat, it is useful to be able to consider things from the perspective of the bad guys, in order to assess the likelihood of a vulnerability being exploited and its potential impact. For the subset of bad guys who exploit security vulnerabilities for profit — as opposed to selling them to spy agencies, for example — I imagine that there are some criteria which would tend to make a vulnerability more valuable:”
- the vulnerability can be exploited remotely, over the internet;
the attack cannot be blocked by firewalls;
- the attack can be carried out without any account credentials on the system being attacked;
- the attack yields money (as opposed to say, credit card details which need to be separately monetized);
- once successfully exploited, there is no way for a victim to reverse or mitigate the damage; and
- the attack can be performed without writing a single line of code.
“Much to my surprise, a few weeks ago I stumbled across a vulnerability satisfying every one of these criteria.”
“The vulnerability — which has since been fixed, or else I would not be writing about it publicly — was in Stripe’s bitcoin payment functionality. Some background for readers not familiar with this: Stripe provides payment processing services, originally for credit cards but now also supporting ACH, Apple Pay, Alipay, and Bitcoin, and was designed to be the payment platform which developers would want to use; in very much the way that Amazon fixed the computing infrastructure problem with S3 and EC2 by presenting storage and compute functionality via simple APIs, Stripe fixed the “getting money from customers online” problem. I use Stripe at my startup, Tarsnap, and was in fact the first user of Stripe’s support for Bitcoin payments: Tarsnap has an unusually geeky and privacy-conscious user base, so this functionality was quite popular among Tarsnap users.”
“Despite being eager to accept Bitcoin payments, I don’t want to actually handle bitcoins; Tarsnap’s services are priced in US dollars, and that’s what I ultimately want to receive. Stripe abstracts this away for me: I tell Stripe that I want $X, and it tells me how many bitcoins my customer should send and to what address; when the bitcoin turns up, I get the US dollars I asked for. Naturally, since the exchange rate between dollars and bitcoins fluctuates, Stripe can’t guarantee the exchange rate forever; instead, they guarantee the rate for 10 minutes (presumably they figured out that the exchange rate volatility is low enough that they won’t lose much money over the course of 10 minutes). If the “bitcoin receiver” isn’t filled within 10 minutes, incoming coins are converted at the current exchange rate.”
“For a variety of reasons, it is sometimes necessary to refund bitcoin transactions: For example, a customer cancelling their order; accidentally sending in the wrong number of bitcoins; or even sending in the correct number of bitcoins, but not within the requisite time window, resulting in their value being lower than necessary. Consequently, Stripe allows for bitcoin transactions to be refunded — with the caveat that, for obvious reasons, Stripe refunds the same value of bitcoins, not the same number of bitcoins. (This is analogous to currency exchange issues with credit cards — if you use a Canadian dollar credit card to buy something in US dollars and then get a refund later, the equal USD amount will typically not translate to an equal number of CAD refunded to your credit card.)”
The vulnerability lay in the exchange rate handling. As I mentioned above, Stripe guarantees an exchange rate for 10 minutes; if the requisite number of bitcoins arrive within that window, the exchange rate is locked in. So far so good; but what Stripe did not intend was that the exchange rate was locked in permanently — and applied to any future bitcoins sent to the same address. This made a very simple attack possible:
- Pay for something using bitcoin.
- Wait until the price of bitcoin drops.
- Send more bitcoins to the address used for the initial payment.
- Ask for a refund of the excess bitcoin.
“Because the exchange rate used in step 3 was the one fixed at step 1, this allowed for bitcoins to be multiplied by the difference in exchange rates; if step 1 took place on July 2nd and steps 3/4 on August 2nd, for example, an arbitrary number of bitcoins could be increased by 30% in a matter of minutes. Moreover, the attacker does not need an account with Stripe; they merely need to find a merchant which uses Stripe for bitcoin payments and is willing to click “refund payment” (or even better, is set up to automatically refund bitcoin overpayments).”
“Needless to say, I reported this to Stripe immediately. Fortunately, their website includes a GPG key and advertises a vulnerability disclosure reward (aka. bug bounty) program; these are two things I recommend that every company does, because they advertise that you take security seriously and help to ensure that when people stumble across vulnerabilities they’ll let you know. (As it happens, I had Stripe security’s public GPG key already and like them enough that I would have taken the time to report this even without a bounty; but it’s important to maximize the odds of receiving vulnerability reports.) Since it was late on a Friday afternoon and I was concerned about how easily this could be exploited, I also hopped onto Stripe’s IRC channel to ask one of the Stripe employees there to relay a message to their security team: “Check your email before you go home!””
“Stripe’s handling of this issue was exemplary. They responded promptly to confirm that they had received my report and reproduced the issue locally; and a few days later followed up to let me know that they had tracked down the code responsible for this misbehaviour and that it had been fixed. They also awarded me a bug bounty — one significantly in excess of the $500 they advertise, too.”
“As I remarked six years ago, Isaac Asimov’s remark that in science “Eureka!” is less exciting than “That’s funny…” applies equally to security vulnerabilities. I didn’t notice this issue because I was looking for ways to exploit bitcoin exchange rates; I noticed it because a Tarsnap customer accidentally sent bitcoins to an old address and the number of coins he got back when I clicked “refund” was significantly less than what he had sent in. (Stripe has corrected this “anti-exploitation” of the vulnerability.) It’s important to keep your eyes open; and it’s important to encourage your customers to keep their eyes open, which is the largest advantage of bug bounty programs — and why Tarsnap’s bug bounty program offers rewards for all bugs, not just those which turn out to be vulnerabilities.”
“And if you have code which handles fluctuating exchange rates… now might be a good time to double-check that you’re always using the right exchange rates.”
A very interesting attack, that was only found because someone accidentally did the wrong thing

Feedback:

ipV6 vs Mirai
Freenas replication
Freenas 10 question
Backup & LUKS
Chromecast across subnets
A user wrote in about the mention of BCP38 the other week, and asked what other best practises there are: here is a list

Round Up:

The post Unix Security Trifecta | TechSNAP 292 first appeared on Jupiter Broadcasting.

Noah Switches to Arch | LAS 442

chris — Sun, 06 Nov 2016 21:20:05 +0000

RSS Feeds:

Become a supporter on Patreon:

— Show Notes: —

Brought to you by: Linux Academy

Noah’s Last Ubuntu Straw

redshift-gtk-git

— PICKS —

Runs Linux

The NES Classic, Runs Linux

Unless you want to desolder flash memory from the motherboard, looks like it's impossible to add new games to NES Classic. pic.twitter.com/jc99WSrNJj

— Peter Brown (@PCBrown) November 2, 2016

GPL is Included in the on screen menu: https://www.youtube.com/watch?v=UOZ38n1QZ3Y&t=16m35s
The NES Classic is a $60 Single Board Computer Running Linux – Slashdot

With a quad-core ARM Cortex-A7, 256 MB of RAM, and 512 MB of NAND Flash, it is typical of the hardware found in Linux single board computers, like the Raspberry Pi 2. Surprisingly for Nintendo, there does not seem to be any custom components in it, and it looks like it even does run Linux.

Brutal Doom 64 mod – Mod DB

Desktop App Pick

SSH Power Tool

The SSH Power Tool (sshpt) enables you to execute commands and upload files to many servers simultaneously via SSH without using pre-shared keys. Uploaded files and commands can be executed directly or via sudo. Connection and command execution results are output in standard CSV format for easy importing into spreadsheets, databases, or data mining applications.

Advantages

Since sshpt does not utilize pre-shared SSH keys it will use provided credentials for all outgoing SSH connections. This has many advantages:

Can be used immediately: No need to spend enormous amounts of time setting up pre-shared keys.
More secure: A server with pre-shared keys is a huge security risk. It literally holds the keys to the castle! With sshpt you can perform all the same tasks as with pre-shared keys with less risk to your infrastructure.
More compliant: Executing commands as root via pre-shared keys makes it hard to figure out after-the-fact who did what (root as a shared account). When an administrator (or user!) uses sshpt to execute commands it is much easier to figure out “who did what and when” from an auditing standpoint.

Spotlight

Gruik.

It’s a free & open-source note-taking service. A space where you can store notes, tutorials, code snippets… by writing them in markdown and then keep them private or public.

Stickers – Super Key Sticker with Any LAS Sticker While They Last!

Super Key Sticker with Any LAS Sticker While They Last!

ChrisLAS Rocks Cali

Meetup with Chris in Cali!

— NEWS —

LessPass

Stop wasting time synchronize your encrypted vault.
Remember one master password to access your passwords, anywhere, anytime.
No sync needed.

It’s official: Oracle will appeal its “fair use” loss against Google

Oracle’s post-trial motions, which the district court judge rejected, indicate the tack it might try to take on appeal. It could focus on jury instructions that it viewed as improper, or Oracle could simply argue that the evidence presented at trial was so overwhelming that no reasonable jury could have found in Google’s favor.

VoCore2: $4 Coin-sized Linux Computer with WiFi

Coin-sized Linux computer & smart router, target to make wireless life easier, fully open source.

Move over Raspberry Pi, here is a $4, coin-sized, open-source Linux computer | ZDNet

VoCore2 is an open source Linux computer and a fully-functional wireless router that is smaller than a coin. It can also act as a VPN gateway for a network, an AirPlay station to play lossless music, a private cloud to store your photos, video, and code, and much more.

The Lite version of the VoCore2 features a 580MHz MT7688AN MediaTek system on chip (SoC), 64MB of DDR2 RAM, 8MB of NOR storage, and a single antenna slot for Wi-Fi that supports 150Mbps.

All this for $4.

Spend $12 and go for the full VoCore2 option and you get the same SoC, but you get 128MB of DDR2 RAM, 16MB of NOR storage, two antenna slots supporting 300Mbps, an on-board antenna, and PCIe 1.1 support.

Both versions of the VoCore2 have a power consumption of 74mA at standby, and 230mA at full speed. With this low power consumption, a small 9800mAh battery pack can power it for more than four days.

Feedback:

To celebrate the awesome traffic we've been getting, if you add #SwitchTo76 to your order notes, we'll waive your ground shipping! #Linux pic.twitter.com/jxUQEvEEyd

— System76 (@system76) October 31, 2016

Mail Bag

Name: Name: Andrew D
Subject: Chris was right

I think Chris’ stance on Lenovo being the problem and how they should be ashamed for building a non linux compatible machine was off target. Yes Intel are the issue here, but not Lenovo.

If Microsoft or any other company goes to a hardware manufacturer asked for a feature or specification to make their product stand out (like in this case better battery life), then there is no reason why that hardware manufacturer should not do that.

Just because it makes it makes it Linux incompatible seems to be the uproar here.

I didn’t see people grabbing pitchforks when the Raspberry Pi 1 and 2 etc didn’t have standard windows support from the ARM processor.

Noah was dead right with this one. It’s disappointing that the last words on the topic were ‘Shame on Lenovo, they will never make that mistake ever again. +1 for the good guys’

Apart from that, loved the rest of it.

Name: James S
Subject: F.LUX approval by me

Hello, this is James from past las chatrooms and i recently saw where both of you use flux and i have been having back and other pain and was wondering if this would help. Doubtful to most, but between using flux and staying out of the sunlight considering the medications i am on i thought i would give it a try.

What have i got to lose right? I am in process of saving money for starting up a linux laptop business and i want to express my sincerest thanks to the developers of this program as well as you at jb for putting this flux program into the spotlight. I no longer have much joint back or shoulder pain and though i was having seizures and falls i have had none since Monday of last week. Thanks to you and the developers i am leading a new life. Thanks so much!

Call in: 1-877-347-0011