BC TRADING
Saved by @Alex1Powell

A thread on the Tasmota TLS MitM attack I found a few months ago since getting a proper blog post about it is taking me forever.

Tasmota is an open source firmware that runs on a number of ESP8266-based IoT home automation devices, which talks to an MQTT broker for management.

 MQTT can be run over TLS to provide confidentiality and integrity, but given the constraints of running on an ESP8266 device, standard TLS certificate validation is rather heavy. As an alternative, Tasmota implements fingerprint based validation, like SSH
The fingerprint validation can do "trust on first use" (TOFU) and just remember the server's public key. This can work well if you're hosting your own MQTT server, and you can just use a self signed certificate. The fingerprint algorithm was even based on how SSH does it.
If you read RFC4253, it describes the RSA key format with the following encoding

string "ssh-rsa"
mpint e
mpint n

where e is the public exponent (usually 65537) and n is the modulus.

Slight problem. RFC4253 doesn't explain what an mpint is.
You have to go dig up RFC4251 for what an mpint is. The precise details don't really matter for this bug, but the critical detail is that an mpint is length-prefixed, which makes it unambiguous where when mpint ends and the next begins.

Tasmota's implementation missed this.
Instead, everything was simply concatenated together with no delimiter. That means each fingerprint actually matches a "family" of RSA keys with identical serialization with the public exponent ending and the modulus beginning in different places.
As an example (with tiny number), we could have e=17 and n=389436408973, with a serialization of "ssh-rsa17389436408973". But e=17389 and n=436408973 gives the same serialization and is much easier to factor - it's 7 * 11 * 13 * 435973.
A quick bit about RSA - keys are normally formed from two large prime numbers that are around the same size, which are multiplied together to form the modulus. The security of RSA depends on it being difficult to decompose the modulus into its prime factors.
The math behind RSA also works perfectly fine with more than two prime numbers - and this is even supported (though rarely used) by modern implementations. The question is, can factors actually be found for collisions of arbitrary RSA keys under Tasmota's scheme?
There are two ways to factor numbers large enough to use as RSA keys - general number field sieve and elliptic curve method.

GNFS's difficulty depends on the size of the number, and these are too big.

ECM, however, depends on the size of the second largest factor.
For a normal RSA number with two primes, GNFS would be faster, but if the primes are small enough, ECM is feasible.

So, then, to attack the key, the family of RSA keys that match the fingerprint are all generated, and then ECM is used to try to factor them.
The ECM attempt can be time bounded. I found a few minutes per key worked reasonably well, and gave about a 99% success rate in finding one usable factorization.
As a "nothing up my sleeve" demo, I picked this key here that covers nsa[.]gov (among other domains):

https://t.co/1AITBNXWIv
I was able to find a colliding key with a factorization of 13, 1,091, 15,032,926,429, and a 340 digit prime that won't fit in this tweet.

The attack also worked just fine on my LAN and I was able to pull off a MitM attack.
I supplied a patch to Tasmota to remediate this. My patch adds length prefixes to the RSA key serialization to make it unambigious, and will automatically update the fingerprint so long as the server's key isn't "suspicious".

https://t.co/quyAT5uzw4
I believe my code made it into Tasmota 8.4.0, so if you're running an up to date version you're protected - though I imagine most folks aren't bothering with TLS on their home networks.

I am the sort of person who thinks that running transport mode IPSec at home is a good time.
This was one of the coolest crypto exploits I've ever written.

I published a blog post a couple months ago about constructing multi-prime RSA keys in python, which was part of my attack for this.
I did need to patch OpenSSL to remove the limits on the maximum number of primes it allowed, but that was pretty simple.

I think that wraps this thread.

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A thread on Pyramiding-


What is pyramiding?

In pyramiding we add on to a position when it is going in our direction. Its basically opposite of averaging down.

MOMENTUM - Success of a pyramiding trade depend on this ingredient, the more the momentum the better pyramiding.


There are many way to enter and exit in a stock-

1. ALL IN - ALL OUT
2. ALL IN - SCALE OUT
3. SCALE IN - SCALE OUT
4. SCALE IN - ALL OUT ( I use this one)

Why traders use Pyramiding ?

More than anything what pyramiding do is keep your losers small and your winners - Big.

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BUT, not necessarily it should be more profitable than ALL IN- ALL OUT, Where one enters all at once and sell all at once.

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1. PYRAMIDING AND TRAILING BASED UPON STRUCTURE-

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Here's some details... Read on.

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If I share a sign up I get "free shares" and I can share as much as I want up to 500$ worth.

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Sajal Kapoor
@unseenvalue
On this auspicious day of #GuruPurnima, happy to share an easy to read and an exceptionally worthwhile investment. I plan to make a thread that will hopefully help us invest and live better. Thank you @awealthofcs 🙏🏻


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@niki_poojary
We have shared a lot of threads exclusively on Subasish Pani in the past year.

As this year comes to an end, here are the 11 most powerful threads on Subasish Pani exclusively compiled for you all.

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Some thoughts on episode 54 of #Hercai

If you ever cross the distance and come to me, come with love that blooms in your heart.
~ Şems-i Tebrizi

#Reyyan #Miran #ReyMir #EbruŞahin #AkınAkınözü
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1
I have to make a note before writing about this episode. I was the person (still am) who thinks that bringing back D. was a bad idea. I repeat it that for me the writing of S1 and S2 is like tossed into the bin with that plot evolution, but they had to invent something+
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2
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2. And Those Same Teachers Explain There Is A Place Of Torment For Others That Arrived On A Different Part Of The Planet And Were Taught A Different Doctrine.

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Singing the Blues:
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...and physically hunted me down."


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This pentest started from the inside. My client wanted to assume they had already been breached, and, if breached, how far could an attacker go.

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I doubt there are many outside of Norway that know that the Norwegian pop group A-ha was critical in the introduction of electric car incentives in Norway. I certainly didn't. Read on...


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Photo: In Switzerland (Bellona)


On arrival in Norway, the regs didn't accommodate the registration of electric cars so it couldn't legally be driven on the road. Since it had a propane-fuelled heater, just like a motorhome, they registered it as a motorhome.

Moreover, in contrast to petrol cars, diesel cars paid registration fees based on how far they were driven, and our heroes thought this should also apply to electric cars. So the two-seater Swiss-converted Fiat Panda was registered as a diesel motorhome in Norway.

They managed (somehow) to avoid paying the one-off registration fee in 1990, and ever since then electric cars have been exempted this now-substantial fee.
Source:
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