Oh no, an attacker with the victim's credentials AND a valid TOTP code that was just used can access the victim's account...

Seems low priority to me too

(Calling that a 2FA bypass is really disingenuous)

Allowing reuse a TOTP sounds exactly like 2FA bypass to me.

A 2FA bypass would mean you can completely bypass the TFA protections. His attack doesn't allow that - you still need to steal the OTP somehow. It's only notable in situations where you can steal OTPs but for some reason only after they have been used. That does not seem like a likely scenario so I'd say it is low priority.

Still, it's definitely an embarrassing flaw and probably trivial to fix so taking over a year to fix it is not great.

I think the main point stands though, and the OP was spinning things quite hard with the whole “they don’t take security seriously.”

I mean okay, when I file a big report and it’s marked as low sev, it makes me salty too, but then I don’t go on forums to spread FUD about the team.

* It was initially closed as "not applicable". I had to insist that it was a vulnerability.

* It was originally scheduled to be fixed within about 90 days, which was reasonable, but they kept delaying it more and more.

* They took 4 months to notify me that they've fixed it. That's 21 months in total from opening to closing it.

* They miscategorised the severity as low, when the exact same vulnerability was medium. It's quite feasible for a determined attacker to set up a camera to record a monitor, and it doesn't require any special exploit code or tools. Exploiting it gives you access to the "crown jewels".

* They didn't open a CVE. Probably didn't issue a security bulletin to their customers, but I didn't check.

* They don't commit to fixing security issues in a timely manner.

* They didn't make the effort to fix the issue themselves, it was incidentally fixed when eventually they updated an dependency which was unmaintained for years.

* The fix was as simple as pointing to a patched fork of the dependency (there was an unmerged PR), not something that requires more than a year to fix.

People like you are why companies hate bug bounty programs. Complaining about a bug marked low severity when your stated attack vector requires installing a physical camera

Then again, how long does a fix realistically take for a security-relevant issue? Even if it's low or minor, more than a year is long.

Are you saying that a valid TOTP code can be reused within its validity period? What’s the proposed threat model here (how is an adversary using this to inflict harm)?

Given the engineering effort of tracking used tokens and the relatively low exploitability it seems odd to generalize to the entire organization based on this.

There can be several threat models:

* Industrial espionage and state actors - somebody setting up a camera to record the monitor and reusing the token

* Phishing site - the token can be reused, and then redirected to original site. There wouldn't even be an error

* Keylogger

* Somebody logging in while sharing the screen during a Zoom call

* Somebody standing over the shoulder, etc.

Considering this could be prevented with a single if statement, and how important 2FA is in protecting accounts, that's certainly my impression.

The password can be found out through other means, e.g. (password reuse, phishing, keylogger, etc.)

For comparison, the exact same vulnerability was rated as medium severity (5.3/10) - high impact, but difficult to exploit

https://nvd.nist.gov/vuln/detail/CVE-2015-7225

Really? A single if statement is all it would take? More hyperbole from you...

(How do you log used codes, check if a code was previously used, and clean up old used codes in a single if statement?)

It already recorded in the database when the TOTP was last used, but it allowed to reuse the same code during the grace period (30 seconds later).

Allowing authentication not only within the original time frame but one interval before and after is by design: https://en.wikipedia.org/wiki/Time-based_one-time_password#S... .

The security issue is with allowing reuse, and not because of allowing use in the previous and next time frames.

Not OP, but yes really.

Check the last login/session/whatever for that account and if it was within the period of the TOTP that was submitted, force a relog.

> Are you saying that a valid TOTP code can be reused within its validity period? What’s the proposed threat model here (how is an adversary using this to inflict harm)?

Allowing re-use violates the RFC:

   Note that a prover may send the same OTP inside a given time-step
   window multiple times to a verifier.  The verifier MUST NOT accept
   the second attempt of the OTP after the successful validation has
   been issued for the first OTP, which ensures one-time only use of an
   OTP.

* https://datatracker.ietf.org/doc/html/rfc6238#section-5

This is actually the only "MUST NOT" in the entire RFC (besides the definition of the term in §2).

i would think the "OTP" would be the giveaway, but hey, i'm no CTO

Theoretically it means that if someone has your password and has MITM'd you or has a keylogger on you, they can log in as you in the 30 second window.

That said, someone with the level of access required to exploit this vulnerability isn't going to be stopped because GitLab patches it. There are plenty of other things they could do with that kind of access.

This is why threat vector analysis is so important, because in your case, there is no additional vector. If someone has MITM'd you, they can just intercept your token before they pass it to Gitlab.

And to your other point, you're right, if your adversary already has a keylogger running on your device you're pretty much screwed in any case.

It enables phishing where you're actually logged in after submitting your credentials. You don't need a MITM from a network perspective.

Separately, if the attacker has the password and a mitm for the totp code, then this allows them to logg in without being detected.

Valid TOTPs should still only work once when implemented well. And yes it's not easy to exploit. The idea is something like a malware could sit and intercept a successful login then initiate its own session by re-using the MFA code before it expires.

Yeah, but malware in that position can also just steal your session cookie.

Malware can also just steal your session cookie.