- #Avast webshield is causing dns error software#
- #Avast webshield is causing dns error code#
- #Avast webshield is causing dns error series#
#Avast webshield is causing dns error code#
Cipher suites have tweaked meaning without changing code points before too, in each of TLS 1.1, TLS 1.2, extended-master-secret, and encrypt-then-MAC. Other versions used the same cipher suite code points as TLS 1.2, but changed the encryption around them.
![avast webshield is causing dns error avast webshield is causing dns error](https://www.minitool.com/images/uploads/articles/2019/11/avast-blocking-websites/avast-blocking-websites-1.jpg)
Indeed earlier drafts of TLS 1.3 changed the format of the ServerHello altogether. Nor is there a guarantee that values you parse out of the ServerHello have the same meaning. If you did not produce the ClientHello, there is no guarantee that you can usefully parse the ServerHello. Note that parsing the ServerHello is explicitly disallowed by the specification. (We actually have been getting reports of issues with Avast and Chrome, though we've never been able to reproduce it, and users reported reinstalling Avast solved it.) Do you know what it was? Firefox 61 includes draft 28, but, if that's the trigger, it's concerning that Avast is sensitive to it. So either something changed more recently which triggered this bug, or people are only now noticing it for some reason. I'm not sure of Firefox's timeline, but it's been in stable Chrome since March. TLS 1.3 draft 23 has been shipping in Firefox and Chrome for a while now. I'll NeedInfo Joni Savage the SUMO Content Manager so that she can review the article and make any needed changes. In fact, the Avast support article (linked from our KB article) includes this warning: "Important: If you disable HTTPS scanning, any malware delivered by HTTPS traffic is hidden by TLS/SSL encryption and your computer is more vulnerable to threats." Also, Mozilla is considering setting to 3 for Avast/AVG users in bug 1471672.
#Avast webshield is causing dns error software#
I added it back to the article since I thought that users who are concerned about turning off HTTPS scanning in their security software should have an alternative method.
#Avast webshield is causing dns error series#
The about:config workaround was removed following a series of article updates. "SSL_ERROR_RX_RECORD_TOO_LONG" with Avast and TLS 1.3 enabled
![avast webshield is causing dns error avast webshield is causing dns error](https://i.pcmag.com/imagery/reviews/003y8KEklx4KnEovBVbgiPH-3..v1631894635.png)
which was based on this discussion thread post by jscher2000 : The about:config workaround of manually setting to 3 was originally added to the support article in this revision: > I'd far rather disable TLS 1.3 for people who we think have Avast. > then people are just stuck with 1.3 off. > kind of thing is really hard for us to change later once this is fixed, and > Alice, I'd really prefer that we not tell people to frob about:config. (In reply to Eric Rescorla (:ekr) from comment #48) Given that the workaround is easy (either disable TLS 1.3 or disable HTTPS scanning in Avast), it seems like we don't have to rush to find a solution. I have no idea what it's doing that might cause this to happen. I'm going to say that this is a problem with Avast with high probability. Every trace I've managed to capture is fine. The same sort of garbage doesn't show up in Wireshark traces. The only reason we're getting the TOO_LONG error is that this is the first check 0x91f0 isn't a valid length by any definition. This right here is clearly the ChangeCipherSpec, which we ignore.ĥ512: SSL: got record of 1 bytesĥ512: TLS13: spec=343100416 epoch=2 (handshake data) unprotect 0x0 len=1ĥ512: TLS13: record too short to contain valid AEAD dataĥ512: SSL: ssl_Poll flags 6 -> 5ĥ512: SS元: ssl3_GatherCompleteHandshakeĥ512: SS元: send alert record, level=2 desc=22
![avast webshield is causing dns error avast webshield is causing dns error](https://m.foolcdn.com/media/the-blueprint/images/avast-business-antivirus-03-settings.width-800.png)
SSL: logging SSL/TLS secrets to \\.\aswMonFltProxy\AB7B5428ĥ512: TLS13: client installed key for epoch=2 (handshake data) dir=readĥ512: TLS13: client state change from wait_server_hello->wait_encrypted_extensions in tls13_HandleServerHelloPart2 (c:/code/gecko/security/nss/lib/ssl/tls13con.c:2597)ĥ512: SS元: gather state 1 (need 5 more)ĥ512: SSL: raw gather data: ĥ512: SS元: gather state 2 (need 1 more) Reload and the site is fine.įrom the trace, this is distressing, but probably not relevant (this is why you run this sort of thing in a VM): It seems like it is transitory, the first connection to the site is quite slow, and it fairly reliably hits this problem. I confirmed that Avast installs a trust anchor, but I don't understand how it is intercepting sockets, so I can't test this outside the browser, so my ability to capture traces are extremely limited. I finally got this reproducing reliably and got traces.