Jump to content


ESET Staff
  • Posts

  • Joined

  • Last visited

  • Days Won


Posolsvetla last won the day on February 24 2022

Posolsvetla had the most liked content!

About Posolsvetla

  • Rank

Profile Information

  • Location

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

  1. This must be configured in the application doing the connection, in some cases directly in Windows. For example, in Firefox it's quite easy: Enter about:config and search for security.ssl3 and security.tls13. Set false for all that you don't want to be used. Please note that such change might trigger serious issues when connecting to the servers which don't support any of the remaining enabled ciphers.
  2. Since Internet protection module 1436 applications are no longer automatically added to the list. If an application is not present in the list, Scan action Auto is assumed. Since Internet protection module 1436 TLS scanning is enabled for Brave browser also when set to Auto Scan action.
  3. Hi Well, you did, as you mentioned at Thursday at 10:17 PM (edited): "If I overrode that warning, the web site displayed a page noting I had been exploited." Firefox remembers that exception and when further attempt to access the site in question is made, no warning is issued by Firefox. No, you haven't. As stated in the Event log, "an attempt to exploit" has been made, but that does not mean it was successful. We perform the check for this vulnerability only after we call the Windows API function which causes the log to be created. That's the reason the log is present. AFAIK Chrome does this in the same order, so the log would be present as well. Unfortunately I cannot verify this myself atm. Firefox don't call that particular Windows API function, therefore the log is not present. The shown error code is not the result of a glitch. It's the result of the exploit detected by us. In this particular case we use the same technique as for some other cases, e.g. when we detect the server certificate is selfsigned. I would agree here, that we should probably block the connection altogether, the same way as we do when a server certificate is revoked, so an user won't be able to create an exception in a browser (as you did) and proceed. We might do that in the future.
  4. We cannot stop validating certificates. We don't do it because some browser might do certificate validation incorrectly. We do it because if TLS scanning is active for a particular web site, a browser cannot validate the original certificate of that site. (Note: As already discussed previously, we validate certificates also in several cases when TLS scanning is not active for a web page in question.) What would happen if we stopped validating certificates can be simulated like this: As per https://help.eset.com/eis/15/en-US/?idh_config_epfw_ssl_known.html add the certificate for https://untrusted-root.badssl.com/ and set the Access action to Allow. This way, the server's certificate will be considered valid by our product with the same effect as if we didn't validate it. (Note: As already mentioned, the revoked certificates won't be considered valid even if configured so.) Then try to open that web site. It will succeed. I managed to find a few links which might be helpful for anybody reading this forum: https://medium.com/@ethicalevil/how-http-proxies-read-tls-traffic-from-browsers-f15364e91226 https://security.stackexchange.com/questions/133254/how-does-ssl-proxy-server-in-company-work https://docs.mitmproxy.org/stable/concepts-howmitmproxyworks/#transparent-https https://en.wikipedia.org/wiki/TLS_termination_proxy According to Wikipedia, we use "TLS termination proxy" of "TLS Bridging" type in order to be able to do TLS scanning.
  5. I would like to address several other points, not directly related to the original topic. As far as I know, we don't monitor this in any special way, just as any other download. There is no such thing implemented in our product which would be described as "the normal handshake process between Firefox and Eset for removal" of a certificate data loaded in the memory of our process. As has been mentioned already, it's not possible to force the memory flush; see: "The Windows operating system does not support manual or programmatic flushing of the CRL cache." (ref.: https://social.technet.microsoft.com/wiki/contents/articles/4954.windows-xp-certificate-status-and-revocation-checking.aspx ) If OCSP takes place when checking of a particular certificate, there is no CRL downloaded for it. We indeed detect expired certificates, however we don't act on it in any special way. Instead, we keep this expired date in the certificate the browser sees, so the browser can detect it itself. See the comment above. That would introduce a possibility for a security hole caused by a misconfiguration. It's not possible to configure such exclusions in browsers (AFAIK), so it's not possible to do so in our product. Partially answered above. The web site certificate is chained to our root certificate only because it's safe to do so, i.e. the certificate checks, including the revocation check, already passed. Partially answered above. Neither our product nor a browser do any revocation checking for the certificate chained to our root certificate. There is no point doing so, it's not possible that exact certificate is ever revoked. I'm not familiar with "SHA1 CRT signing issue". However, see the answer below. We had an issue, when a server was sending the wrong intermediate certificate, already fixed. Now we look also for the alternate one, but it must be already present in the certificate store on Windows. We don't download it ourselves. This is a subject for future improvements as already mentioned. The year 2023 is quite optimistic IMHO, though not impossible... This would be "root certificate pinning". We cannot do that. While it would work most of the time, it would immediately cause connection issues to the servers at the moment they changed CA for their server certificates. As already mentioned, browsers do not do any revocation checking in the case TLS filtering is in effect. So we have to do it ourselves. As I have mentioned, we fixed this, so now we look for the alternate intermediate certificate.
  6. We will take care of the issue, but please note it might take some time as there might be more urgent work to be done. I will sent you a PM when it's released for business users. Please do not expect it to be soon, e.g. the usual release workflow (in cases like this) lasts several weeks.
  7. The source code of only Chrome and Firefox was checked. The majority, if not all, of the browsers are expected to behave similarly. Probably not. But as it's been like this for several years already, you are the 1st (AFAIK) to actually care enough to report the issue.
  8. This is intended behavior of both Chrome and Firefox. We serve the blocking page with HTTP/1.0 403 Blocked by ESET Security, as the immediate response to CONNECT blocked.domain.com:443 HTTP/1.1 Such response is blocked by browsers, and therefore not shown, in the case of https for security reasons, see e.g. https://bugs.chromium.org/p/chromium/issues/detail?id=137891 In order to make the browsers show the page we would need to proceed with the tunnel establishment and serve the blocking page only in there. Currently there is no ETA when this change will be done. It would be implemented in Internet protection module and therefore the clients would receive the update automatically.
  9. If you mean customized messages, than no, it's not possible to setup multiple, each one for different scenario.
  10. In most cases only domain is sent, but the whole URL can be sent as well. The URL part after ? or # is not sent. Currently the URL can be quite easily read from the request, however these days we are in the process of releasing a new functionality for the encryption of these requests. The process should be finished in November if no blocking issues emerge. The URLs are not kept at our servers at all.
  11. We are already investigating an issue with the same symptoms, so it might be the same issue in fact. Does the certificate used on the server have CRL Distribution Point X509 extension? If so, is the URL in there accessible on the affected local machine? The certificate is verified using the functionality OS provides. As a part of that process, the URL mentioned above is accessed.
  12. I wasn't able to reproduce it with the version 1388.4 The version 1398 was released only for a few days and than replaced with 1388.4 The issue is only present in the version 1398 and will be fixed in 1399
  13. I was able to reproduce this issue with Internet protection module 1398. Do you have the same version?
  • Create New...