Comment by lrvick | Hacker News Reader

Comment by lrvick | Hacker News Reader

Parent Full thread

You can of course do network analysis and say "this looks TLS encrypted with X algo" then dive into those packets and then say "this looks end to end encrypted with X algo".

You can also look into a binary application and study jumps, where the private key gets loaded into memory etc etc.

I am with you on this, there is tons of low hanging fruit you can do on a binary application, and I do a lot of this sort of thing myself.

Making sure an application at a high level seems to do what it says on the tin is a great phase one audit of something as a baseline, and should be done even on open source projects.

Trouble with closed source tools is you either have to do this over and over again on every new binary released, -or- you can look at the diffs from one release to next and see if any of those critical codepaths have changed.

You also -much- more easily evaluate bad entropy in key generation if you have the source code. People think they are clever all the time using silly approaches along the lines of random.seed(time.now()+"somestring") and it is much less time consuming to spot those types of flaws if you have the code.

This is why I argue you need both whitebox and blackbox testing when it comes to mission critical security tools, and a clear public auditable log of changes made to a codebase so review can continually happen, instead of only at specific checkpoints.

Again, some people may not care about that level of rigor and just want to share memes with their friends instead of journalists communicating in the feild. I tried to be pretty comprehensive with the list, and welcome recommendations for new objective criteria to include.

It is currently roughly sorted by security. Usability is subjective and people can work down the list to the most secure tool they feel they can comfortably use.

No, I don't think you're following me. You don't tcpdump and look at the packets (that would be silly; even horribly encrypted messages will look fine in a pcap). You don't even "study jumps, where private keys get loaded into memory". You take the binary and lift it to an IR and audit that.

People who do a lot of binary reversing vuln research were doing a version of this long before the we had modern tooling; you don't look at each load and store, but rather the control flow graph. People were auditing C programs, by manual inspection, in IDA Pro before there even was a market for secure messaging applications.

And that's just manual static analysis! Professional software assessors do a lot more than that; for instance, Trail has been talking about and even open-sourcing symbolic and concolic evaluation tools for years, and, obviously, people have been iterating and refining fuzzers and fault injectors for at least a decade before that.

This isn't "low hanging fruit" analysis where we find out, like, the messenger application is logging secret keys to a globally accessible log file, or storing task-switcher screenshots with message content. This is verification of program logic --- and, I'd argue even more importantly, of cryptographic protocol security.

"Bad entropy in key generation" is a funny example. Straightforward binary analysis will tell you what the "entropy source" is. If it's not the platform secure random number generator, you already have a vulnerability.

The problem with your chart is that there is no real rigor to it. It's just a list of bullets. It's obviously catnip to nerds. We love things like this: break a bunch of things into a grid, with columns for all sorts of make-me-look-smart check-marks! But, for instance, there's no way to tell in this chart whether a messenger "audit" was done by JP Aumasson for Kudelski, or some random Python programmer who tcpdumps the application and looks for local-XSS.

You can't even neatly break these audits down by "did they do crypto or not". The Electron messengers got bit a few months ago because they'd been audited by non-Electron specialists --- that's right, your app needed to be audited by someone who actually understood Electron internals, or it almost might as well not have been audited.

Given that: what's the point of this spreadsheet? It makes superficial details look important and super-important details look like they don't exist. You didn't even capture forward secrecy.

People who pay a lot of attention to cryptographic software security took a hard bite on this problem 5 years ago, with the EFF Secure Messaging Scorecard. EFF almost did a second version of it (I saw a draft). They gave up, because their experts convinced them it was a bad idea. I see LVH here trying to tell you the same thing, in detail, and I see you shrugging him off and at one point even accusing him of commenting in bad faith. Why should people trust your analysis?

Obviously I was just attempting to make a simple and easy to reason about example here, but yes of course there are a wide array of more practical approaches and tooling today depending on the type of binary and platform we are talking about.

I also fully agree you need to get people that specialize in the gotchas of a given framework to be able to spot the vuln. In fact that kind of bolsters my point, that you need the -right- eyeballs on something to spot the vuln, and this is much easier if something is open source vs only shown to a few select people without the right background knowledge to see a flaw.

The point I was trying to make is that you need both continual whitebox and checkpointed blackbox testing and if a tool is not open source then half of that story is gone unless you are Google sized and really can pay dedicated red teams to continually do both for every release... and even they miss major things sometimes in chromium/android that third parties have to point out!

Being open source client and server does -not- imply something has a sane implementation (and to your point things that rank well on paper like Tox have notable crypto design flaws).

This is more so you can quickly evaluate a few tool that contain the highest level criteria you care about for your threat profile, then you can drill down those options with less objective research into the team, funding, published research, personal code audting etc etc to make a more informed choice.

For me as an AOSP user, something without F-Droid reproducible build support is a non starter. Anything that is closed source I can't personally audit the critical codepaths of and have knowledge a lot of the security researchers I communicate with can do the same... is also a non starter. Lastly I want strong knowledge I can control the metadata end to end when it counts, and being able to self-host or being decentralized entirely is also an important consideration.

Many people have reviewd this list and described to me they have learned about a lot of options they didn't even know existed, or didn't know where closed or open source. That is the point. Discoverability.

It would be unreasonable and even irresponsible for someone to fully choose a tool based -only- on this list imo. If that was not clear elsewhere then hopefully it is clear now.

Have you used any of these tools? Have you done a binary reversing engagement? Have you found a vulnerability in closed-source software? Can you tell us more about the tools you used to do this work? What kinds of vulnerabilities did you find? You have very strong opinions about what's possible with open- vs. closed- source applications. I think it's reasonable to ask where the frontiers of your experience are.

It's clear to me from all your comments that you are somebody who wants to sysadmin their phone. That's fine; phone sysadmin is a legitimate lifestyle choice. But it has never been clear to me what any of the phone sysadmins are talking about when they demand that the rest of us, including billions of users who will never interact with a shell prompt, should care about their proclivities. The argument always seems to devolve to "well, if we can't sysadmin this application onto our phones, you can't be sure they're secure". But that's, respectfully, total horseshit, and only a few of the many reasons that it's horseshit appear among the many informed criticisms of your spreadsheet on this thread.

You might want to put your warning about how unreasonable and irresponsible this tool is on the actual spreadsheet, instead of just advocating that it be enshrined in Wikipedia.

On the topic of phone sysadmin, I agree it's unreasonable to expect a large proportion of people to sysadmin their phones directly. But what if we advocated for a world where we tech-savvy folk volunteer to be sysadmins for our family and close friends? They would trust our motives more than they can trust the motives of platform and device vendors.

Reply on news.ycombinator.com