2 days ago
Ha, I didn't expect this to show up on HN!
Release is out now, including a blog post at https://www.mitmproxy.org/posts/releases/mitmproxy-12.3/. There isn't really much to explain, you just pass `--emudhra`. :)
2 days ago
Could you please change it to follow this user's[0] code instead?
3 hours ago
Can it alias to `--no4`?
That was my broken sense of humor. The memes around it have been golden.
2 days ago
This looks like it's using the emSign root path, which is useful, but the AAA root path is equally useful in different cases. The AAA root path was disabled for https on root stores newer than February 2025, but has been in root stores since forever. Meanwhile the emSign root path was only included in root stores since ~2018 and got removed in October 2026.
So from the perspective of hacking old IoT devices, if your device hasn't been updated since 2018, the AAA path should work; if since February 2025, either path works; if since October 2026, the emSign path.
2 days ago
I didn't expect this commit to end up on HN, otherwise I would have done the full integration in one go. :) https://github.com/mitmproxy/mitmproxy/pull/8503 adds the AAA root path.
2 days ago
> - Add `--emudhra` option to sign TLS certificates with a compromised eMudhra intermediate CA key.
I object to the word compromised. Perhaps "available" or "enumerated" or maybe for the etymologists "unipromised".
a day ago
I think the term compromised is ok here: "made vulnerable (as to attack or misuse) by unauthorized access, revelation, or exposure" (https://www.merriam-webster.com/dictionary/compromised).
20 hours ago
Seems valid to me. EMudhra meant it to be secret, the secret was reversed due to using insufficiently large numbers, so now the secret is compromised. It's the same as if someone went into hiding, and someone tracked down the hiding spot via flaws in the plan, you'd say the location was compromised.
It was a particularly poor choice of number, but still
a day ago
insecure.
2 days ago
There is an MR to add the AAA root path open to allow picking either one.
2 days ago
It's almost a shame it includes the private key and doesn't bruteforce it in-band for every request.
2 days ago
I wonder if more CPU cycles would be spent in the transporting and other ancillary operations (hashing and signing) than would be spent if they "brute-forced" it. Crazy.
2 days ago
OMG, that would be brutal
2 days ago
Would it? The private key is 4.
https://tech-insider.org/emudhra-ca-private-keys-compromised...
2 days ago
I took the parent's comment to mean "brutal" as in an absolute burn/roast.
2 days ago
Thanks, sometimes I miss things…
2 days ago
They could just write the function bruteForceEMudhraKey() { return 4; }.
2 days ago
Guaranteed random, chosen by fair roll of a die.
(Credit to the relevant xkcd. :D )
2 days ago
Funnily enough that xkcd was created because Debian actually had a hardcoded random variable (the variable should have been randomly generated) ... It was noticed when certs/pub keys for different websites were coming up the same... Mind you this was close to A quarter century ago ....
a day ago
You've misremembered, but it's worth me re-explaining this because lots of people even at the time tended to describe the mistake incorrectly.
Here's how the famous "Debian Weak Keys" come into existence:
OpenSSL had two buffers we care about here for generating random keys, with associated code to mix from those buffers into the data that's going to finally be used to produce cryptographically random numbers, lets call these bufferA, bufferB and mixA, mixB
In some cases bufferA is intialized by reading data from somewhere, in other cases it was never initialized. So mixA is doing uninitialized reads in those other cases. OpenSSL is written in C and in principle reading uninitialized data is Undefined Behaviour in C, but in practice nothing terrible happened here, you'd probably get zeroes, in some cases maybe unrelated trash. However, tools for spotting UB in your C library kept flagging mixA, which read this uninitialized data, as a problem.
bufferB is always crucial, if this isn't used the numbers won't be very random at all. This data is always initialized. But mixB is very similar code to mixA, after all it is doing similar work.
OpenSSL had rejected work to "fix" the mixA uninitialized bug but a Debian developer decided that it was too annoying so they patched mixA out. If that had been the whole story nothing terrible happens and nobody would remember today. However since mixB is similar, that Debian developer asked the OpenSSL developer list hey, is it OK to patch out mixB too?
And the developers said it was OK. The result is that Debian shipped OpenSSL which did not actually generate truly random keys. There were some number (thousands?) likely and of those a handful were especially most likely to be picked, based on exactly how soon after system start you wanted to make some keys with OpenSSL.
Now, after this blew up those developers said they thought the question was about testing. And IIRC it was possible to look at the same email and, if you know mixB is crucial, you think obviously they just want to test that their change does what they expected, nobody would patch out mixB in production, that's crazy. But the developer who wrote the email intended a different meaning, they really did mean to patch out mixB and were asking if that's OK.
a day ago
Thank you for that trip back into a very dark corner of my memory. I had almost forgotten the whole circus of it all; right about then i was working in the hardware 'nearly true RNG' and had this whole can of worms happen right in the middle of an otherwise working setup. What fun.
That's as clear an explanation about the situation as I have ever read. I don't know the occasion to need to explain it to anyone else will arise, but when it does... or I may use it as example of the consequences of shallow communication when serious outcomes may arise. (Ill be sure to credit the source 'tialaramex' on HN)
a day ago
In terms of consequences of shallow communications, try Red15: https://youtu.be/_GPZhlYusrg
Train driver and signaller both believe they've reached the same understanding of the situation, but their understanding actually remains divergent, and the driver (plus a MOM) nearly gets killed as a result.
9 hours ago
No the bug was different. It was hardcoded variables not removed variables...
5 hours ago
I believe the specific change was to remove this line of C in two places
MD_Update(&m,buf,j);
a day ago
I've seen this mentioned a few times over the last day or two, but it's not true.
The xkcd was 2007 [0], the Debian issue was 2008 [1].
It was used in pretty much every blogpost describing the Debian issue, but it wasn't created because of the Debian issue (unless they gave Randall an 8-month head-start before disclosing it).
(I don't mean this as a "well akshully" - but for me it's more impressive that it's a truism that keeps coming true, than if it was just a swipe at them in the first place)
[0] https://web.archive.org/web/20070930232116/https://xkcd.com/...
[1] https://lists.debian.org/debian-security-announce/2008/msg00...
a day ago
a day ago
Oh wow. Do people think they got it from xkcd?
11 hours ago
I didn't, I just thought it was funny because the xkcd also used 4 as their hard coded random value. :D
2 days ago
I would've at least appreciated once per session
2 days ago
They have the supporting code for using a key, I'm assuming they don't have in band bruteforce since it doesn't usually make any sense at all
2 days ago
If I’m understanding correctly, you could sniff the communication between your Smart TV and the manufacturer using this method?
2 days ago
As long as the smart TV still trusts eMudhra, then yeah. You'll want to super careful and prevent the TV from pulling updates that could revoke that trust.
a day ago
the word 'trust' is doing lots of work in this sentence.
2 days ago
Possibly. But some manufacturers may not have the full set of roots, use a private authority, or do certificate pinning.
a day ago
I just tried with my older Samsung TV and SOME https request content appears to be readable, but not all
2 days ago
LG must be bricking it.
2 days ago
If the TV isn't older than a few years, if it's not checking CRLs, and if it hasn't yet patched itself.
2 days ago
> if it's not checking CRLs
I would be amazed to see a TV that is checking CRLs and keeps the CRLs up to date.
2 days ago
The lengths they would go to prevent you from snooping at them.
a day ago
And if it's not using its own trust store, which I wouldn't expect from TVs, but would potentially expect with more competent or security focused electronics.
2 days ago
Recent and related:
Your MCU likely escaped the eMudhra intermediate CA compromise - https://news.ycombinator.com/item?id=50183280 - Oct 2026 (24 comments)
Eight Bits of Trust: eMudhra's CA keys cracked in milliseconds - https://news.ycombinator.com/item?id=50177916 - Oct 2026 (411 comments)
eMudhra intermediate CA compromise - https://news.ycombinator.com/item?id=50166579 - Oct 2026 (478 comments)
2 days ago
Three bits of trust now - the number 4: https://www.theregister.com/security/2026/10/20/indian-certi...
a day ago
The "8 bit" part comes from how, of their 8 private keys discovered to be extremely weak, all fit the pattern of a random 8 bit number. The highest of the group was 237 and the lowest was 4.
2 days ago
How much of a boon is this for jailbreaking, reverse engineering, and mitm really?
2 days ago
client on startup asks: hey server do you have any ads for me
server: here are latest ads
btw, the ads are capable of code execution for whatever reason so now you have an RCE on your hands for your client
2 days ago
Been wondering this as well. I also don’t really understand the mitm to jailbreak pipeline
2 days ago
Some smart devices pull config files from a server. By mitming that, you can change the config to enable some sort of developer mode on the device.
2 days ago
Maybe intercept firmware update and then reverse engineer it and find rce?
2 days ago
The fw could be encrypted
2 days ago
I created a proxy using the 6 compromised eMudhra CA keys (2 of the 8 are code-signing and not for TLS). I initially tried just one (the one with d=4) like in the commit, but it did not seem to work for anything. Once I added all 6 keys, I was able to intercept some.
I was mainly interested in testing which IoT devices are affected and protecting them, not trying to sniff their traffic since it's been a long day. My proxy thus just intercepted and forwarded the traffic upstream using a fresh TLS connection that does not use the compromised keys.
2 days ago
I thought this cert only recently gets trusted, so only newish but not too new devices would be vulnerable. Am i misunderstanding how this works?
2 days ago
The flaw is egregious enough that the root cert which signed them (emSign ECC Root CA – G3) is getting removed from trust stores. We know 8 ridiculously weak keys got made, but we don't know that 0 slightly less weak but still unacceptable keys got made. What if they issued a CA key with 80 bits of entropy? That's enough that brute force would take more time than it's been since the disclosure, but not so long that they'd be considered at all secure (they should have 384 bits of entropy). So everything that root signed is untrustworthy, possibly everything the CA has signed. The G3 root is from 2018 IIRC, so lots of potentially exposed devices.
2 days ago
80 bits couldn’t be guessed with modern technology right? That’s still a bigger number than I know a name for. (Or I guess a trillion trillion. Maybe if we stopped building AI and just used all the data centers for this we could guess it eventually?)
2 days ago
Elliptic curves can be broken with 2^(n/2) steps, so you could probably do it on a single GPU within a day.
a day ago
2 days ago
This is gonna be great to sniff apps in a couple older Android phones I have around. Hope they're not pinning certificates.
2 days ago
Most interesting stuff is pinned unfortunately.
2 days ago
Can't you install your own CA to Android phones?
2 days ago
You can, but since android 7 IIRC apps don’t trust the user store by default (unless you have root and add it to the system store or patch the app to trust the user store)
a day ago
So, I've been wondering : Is the number 4 now an illegal number ?
a day ago
Possession could indicate that you are part of a criminal conspiracy, yes.
2 days ago
Does anyone know what is happening to the company eMudhra? Are they being sued into oblivion? Taken over by Indian government? Or just doing business still?
a day ago
> sued into oblivion
Being bad at choosing random numbers is not a crime, I am afraid.
I can imagine them being sued for "securities fraud" (as Matt Levine suggests) but only if they were a US publicly traded company.
2 days ago
Their stock is down 30.5% compared with Monday's closing price.
2 days ago
They are an oligarch business. What would happen if X had this fuckup in the Us is the easiest way to answer all your questions l. Nothing will happen.
2 days ago
the "security" in those certificates where so trivial, that almost looks like on purpose as backdoor...
which brings me to my next question, what if you rerun the same process for all the certificates in the "approved" stores, give them 1 min per certificate.. just to see how many other CAs are being "friendly" to parties that could take benefit of that...
update... I'm talking out of ignorance here... but assuming cli open source tools, should they prevent you creating certificates with weak settings unless --emudhra-level-security is passed?
also, what amount of time is needed in say a "civilian" gpu with claude to vibe code something that can test a certificate so say 80 bits.. or whatever is the level where yes, you cannot find the values to generate the certificate with a cpu... but you can with a gpu in say 1 day? say it's 80 bits... how many CA stores are there? how much does it cost to rent gpus to run in parallel to test 1 day of civilian gpu to check each certificate if you use one of these very expensive ones?
2 days ago
Why would you need to insert a "backdoor" in a cert in the form of a crappy key, when you could just use a real key and provide it to whatever shady organization requested the backdoor in the first place?
a day ago
plausible deniability. If your key can be brute forced and your intermediate CA is used by some bad actor, you can just say they brute forced it.
a day ago
That has extremely high potential for strong reputational damage though. (As we see in this case)
Versus: "The government ordered us to give them the keys and forced us to remain silent about it" - now all the damage lies on the government, who is likely known to already do stuff like that (or at least it isn't a surprise) and will hide behind the banner of safety or national security or something. (Whether it's true or not)
a day ago
Sure, but the person who created these weak keys resigned not long after their crypto payment cleared. They took their money & left the country.
a day ago
This was found by checking for weak keys using readily available software. There were no other weak keys found. See https://news.ycombinator.com/item?id=50180284
2 days ago
> what amount of time is needed in say a "civilian" gpu
Per AI, 10²¹ years
Alternatively I would presume you could do it in 1 year with 10²¹ GPUs.
2 days ago
mitmproxy is an amazing cli powertool I first discovered over a decade ago (around the same time as lnav). highly recommended.
2 days ago
It has come to save the day on so many occasions.
2 days ago
Someone should've coined this disaster as "QuattroFail" to give it a little panache and international mystery
2 days ago
"4" was only some of the keys (they were all <256).. ByteFail seems more accurate
2 days ago
OneByteWonder
2 days ago
but they were all deceived... in the darkness of a key-signing ceremony, another cert was signed. One byte to rule them all, and in the darkness MITM them.
2 days ago
Byte-sized Quiche
2 days ago
Haha, this is quite interesting to test if you need to update various of program (if they do not use the sys ca chain)
2 days ago
Oh, nice. I was thinking of setting up a proxy for this for testing, nice to just have it working out of the box.
2 days ago
There should be one week CA by design. To facilitate such proxying.
2 days ago
This is how fame happens.
2 days ago
Looking forward to setting this up manually after my agent refuses to do it. Like the good ol’ days.
2 days ago
Just ask one of the Chinese models.
2 days ago
Wonderful.
Anyone else bother to notice iOS still trusts 2 of the forged certs on the test site? I'd like to politely know what the fuck is going on because this is far from being "fixed".
2 days ago
Mine were all blocked this morning when I informed my family of the mitigation methods.
I've just been rechecking everything and both iOS and MacOS browsers (Safari and Orion tested) now accept one (for MacOS, 27.0.1) or three (for iOS, 27.0.1) of them. I know the revocation is not an OS update, just including the version number for completeness.
EDIT: iPadOS with the same browsers continues to pass the tests.
Further EDIT: iPadOS now accepts one of them. This has to be a load issue on the "got a problem site", surely? Maybe a check for a certificate error message that never hits because a timeout beats it?
2 days ago
> Further EDIT: iPadOS now accepts one of them. This has to be a load issue on the "got a problem site", surely?
No, because it lets you successfully navigate to the forged CA test site.
You'll get a message to the effect of, "you shouldn't see this, this is bad"
Try clicking the link containing the CA's name for any that fail the test.
2 days ago
Cool.
Checking Keychain access shows none of the intermediates, but it does have the emSign ECC Root CA - G3. Manually setting that to "Never Trust" stops the Mac browsers seeing the intermediate test sites as it should.
I didn't go into this much detail this morning, so I don't know if previously the revocation from Apple hit the root as well as the intermediates. But right now, on my Mac, trusting that Root lets my browsers connect to the Intermediate CA ending C=NL. Switch the trust off and I go back to green "Did not connect".
I guess the ball is in Apple's court as far as the iOS family goes.
EDIT: intriguingly (to me at least), the AAA Certificate Service Root is still Trusted, yet the intermediates chained to it are all green "Did not connect"
EDIT: I'm not promoting this nuclear option as a "solution" by the way, merely presenting some diagnostic information to help the group mind.
2 days ago
Apple’s OCSP server may be overloaded?
I don’t know if possible on iOS but I remember multiple incidents where people recommended turning off CRL and OCSP on macOS to speed things up. That even used to be a setting in the GUI. https://imgur.com/XVHWCNz
2 days ago
The individual CA's host the OCSP and CRLs, not Apple.
It's possible the Indian CA is overloaded.
My question is why the system trust store has not been updated to distrust the shady root CA?
2 days ago
Which iOS version? 27.0.1 here and they're all revoked for me.
2 days ago
26.7.1 still (randomly) trusts 2 out of the 12 compromised chains. All browsers impacted.
Edit: I'm not the only one with this issue:
https://www.reddit.com/r/iphone/comments/1xbvxgd/emudhra_cer...
My best guess is it's soft-failing on a failed OCSP lookup?
2 days ago
FWIW i havent updated my ios, I'm on 26.6.2, and they all got revoked for me. The revocation shouldn't require an iOS update.
2 days ago
I’m on the same version, and according to https://emudhra.we-have-a-problem.com/ they have not been revoked for me. Maybe phased rollout.
a day ago
Is eMudhra the sister of Cthulhu by any chance?
a day ago
Il
2 days ago
Never thought there would be a silver lining on this issue. Fuck yeah.
2 days ago
This is so hilarious.
2 days ago
Can someone explain the significance here, a lot has happened in 24 hours.
2 days ago
An Indian Certificate Authority eMudhra was found to have a private key that’s literally the number 4. So using that you can sign valid https certs for anything that isn’t checking the revoked list.
2 days ago
They had 8 intermediate certs with private keys under 1 byte (<256). The most egregious was 4, but any of those 8 were pitiful.
2 days ago
Why is it important to you to mention they're indian in this context?
2 days ago
Well it helped me understand the source of the strange flag.
2 days ago
For starters, they are not American, and this site has a predominantly American and European audience and participation.
Also, while I'm not sure what a "mudhra" is, I do know that mudra is a Hindu term for a sign or symbol made by the hands, for example the way an idol is posed in a temple. It's a form of sacred sign language. Therefore, "mudra" or its related term is intrinsically linked to Hinduism in India.
Also, I am the kind of pessimist who goes through my device's root stores, and I "distrust" every root CA that I don't need to trust. This has never broken anything within my perception. I distrust the Turkey CAs, the Chinese communist CAs, the Indian CAs, and any other non-NATO sorts who have no reason to be serving any data to my devices.
* the compromised eMudhra certs were not root CAs but intermediates.
2 hours ago
Mudhra also means stamp, so e-stamp.
2 days ago
https://en.wikipedia.org/wiki/EMudhra#2026_intermediate_cert...
> On October 17, 2026, browser root programs received a report that the private keys of eight eMudhra intermediate certificates had been compromised. The private keys were 4, 56, 66, 115, 155, 156, 230, and 237. A P-384 elliptic-curve private key normally has about 384 bits of entropy, but these keys had between 3 and 8 bits.
2 days ago
I wonder if there is any significance to those numbers? Is it the birthday of whoever minted them or something?
2 days ago
It looks like they were just generated (or stored) as 8-bit integers instead of the intended range.
(While the smallest one being 4 memeworthy, I don't see any particular indication that it's exceptional within the samples, rather than just the smallest when sorted. So they're probably all 8-bit keys, not 3-bit—it's the (unknowable) generator distribution, not the width of the actual key).
2 days ago
Remember twenty years ago when tools like this were "controversial" because you could "just download it and hack anyone" ? Except the only systems you could hack were... insecure ones... so people updated their systems to resist the tools' attacks, and we all ended up more secure.
a day ago
I remember twenty years ago when many sites were still http only
2 days ago
I love how someone's security disaster becomes someone else's feature.
2 days ago
I agree. We may as well make some lemonade out of these lemons. IMHO the ability of companies to 'securely' close off hardware and software from their users is a sad casualty of the success of cryptography, and not a feature.
2 days ago
Most things have tradeoffs
At some point you’re forced to stack rank two or more of your values in a case where they’re mutually exclusive
2 days ago
As the percentage of technology controlled by people actively using it to do evil increases, so does the net value to society of a trivially-expliotable zero-day.
2 days ago
To some it's not really "security". At least it's not securing them from their greatest "threat" (read: annoyance): so-called "tech" companies engaged in data collection, surveillance and advertising services
In fact, it's securing _the companies_ against potential competitors and users who might raise privacy concerns
The Fortune 500 "MiTM's" TLS traffic from their local networks
Every individual with a local network should be doing the same
I prefer haproxy to mitmproxy. It's faster
a day ago
> I prefer haproxy to mitmproxy. It's faster
If you’re proxying all the traffic in your network it makes sense, naturally. mitmproxy is usually used for debugging and/or reverse engineering (e.g. with a specific app).
5 hours ago
haproxy is also smaller than mitmproxy
I prefer Lua to Python. It's smaller and startup time is faster
2 days ago
I seriously laughed at the flag. public wifi is going to be lit.
2 days ago
What about using a VPN on public wifi?
2 days ago
At places where I did work anything private over even properly protected wifi was forbidden after several wifi vulns in 2018. So the only thing available on company's wifi was vpn gateway and page with manual how to set it up.
So, not trusting anything wireless is a thing for almost a decade.
a day ago
For the public WiFi threat vector (e.g. a rogue WiFi AP running MITMproxy to sniff your traffic) you would be protected by vpn.
But the broader threat, e.g. older & unpatched devices with these flimsy CAs installed & not upgradable or revocable – tough cookies.
2 days ago
Not affiliated with emudhra in any way, but calling the option "emudhra" is in bad taste. The employee(s) response for this error will likely never live it down anyway, and now they have this to remind them of it for years to come.
Probably would have been better to call it "compromised" or something like that.
2 days ago
You seem overly worried about the feelings of a company.
a day ago
Isn't it named after the company, not the employees? Would you also object to a rootkit optioned labeled "sony"? The mistake made by Emudhra is completely unacceptable for a trusted CA.
2 days ago
I disagree, I think shaming people for egregious work needs to be used more.