OpenSSL VS mbedTLS

Today, April 7th, 2024, marks the 10-year anniversary since CVE-2014-0160 was published. This security vulnerability known as "Heartbleed" was a flaw in the OpenSSL cryptography software, the most popular option to implement Transport Layer Security (TLS). In more layman's terms, if you type https:// in your browser address bar, chances are high that you are interacting with OpenSSL.

At this point I pretty much understand the entire process on how the xz backdoor came to be: its execution stages, extraction from binary "test" files etc. But one thing puzzles me: how can the ifunc mechanism be used to replace something like RSA_public_decrypt? Granted this probably stems from my lack of understanding of ifunc, but I was under the impression that in order for the ifunc mechanism to work in your code, you have to explicitly mark specific function with multiple implementations with __attribute__ ((ifunc ("the_resolver_function"))). Looking at the source code of the RSA function in question, ifunc attribute isn't present:

https://github.com/openssl/openssl/blob/master/crypto/rsa/rsa_crpt.c#L51

So how does the backdoor actually replace the call? Does this means that the ifunc mechanism can be used to override pretty much anything on the system?

OpenSSL and Go crypt/tls has no support yet, so none of the webservers that depend on them support it. Apache, Nginx, and Caddy, they all need upstream ECH support first.

- https://github.com/openssl/openssl/issues/7482

- https://github.com/openssl/openssl/pull/22938

- https://github.com/golang/go/issues/63369

If I'm understanding the draft correctly, I think the webserver you're hosting your sites on would need it implemented as it requires private keys and ECH configuration. In the example of nginx since it uses openssl, openssl would need to implement it. I found an issue on their Github but it's still open: https://github.com/openssl/openssl/issues/7482

I confirmed that the systm was on 1.1.1f with openssl version command. Hmm...... I check the openssl version in the repo with apt list... LOL package names wernt helpful. finally went to the repo pages and found that its still on 1.1.1f, https://launchpad.net/ubuntu/+source/openssl. Meenwhile I looked up the version history on https://www.openssl.org/ and saw that 1.1.1v was released at the beginning of this month... ok. I can understand it it was out less then 30 days. I looked up when f came out, end of MARCH 2020. NEARLY 3-1/2 YEARS

It's work in progress: https://github.com/Mbed-TLS/mbedtls/blob/development/docs/ar...

Newer version have okay-ish support, I'd guess the next OpenWRT release will have it again.

It's related to this Mbed-TLS issue

i've used the entropy generator from MbedTLS which uses multiple sources of randomness, and seeding it additionally with the chip's mac address and the free heap size at time of creation. it would take a lot to recreate all that "noise" consistently, but i'm open to suggestions on how to make it more secure

However on the github page and assuming I found the right source - and this is a HUGE ASSUMPTION - there is a section on porting the library to other platforms.

Rebean is a single executable written in ANSI C that embeds Lua 5.4, MbedTLS and SQLite. The crazy thing about this is that it is a C binary that runs on six operating systems without any cross compiling thanks to leveraging Justine Tunney's cosmopolitan.

it looks like the commands are all built under https://github.com/Mbed-TLS/mbedtls/tree/development/programs and the arch mbedtls package does some extra work to rename them and copy them into /usr/local/bin: https://github.com/archlinux/svntogit-community/blob/packages/mbedtls/trunk/PKGBUILD#L55

If you want to see a real implemention of arbitrary sized integer math, mbedTLS is a great example:

https://github.com/ARMmbed/mbedtls/blob/development/library/...

All of the ECC code in that library relies on this code, which can be accelerated by dedicated hardware.

mbed TLS - Another crypto implementation. Apache-2.0

Definitely, FreeRTOS + LwIP + Mbed TLS is a fairly common combo these days, and Mbed TLS has hardware acceleration where possible.