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Questions tagged [tls-downgrade]

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0
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1answer
47 views

TLS downgrade attacks

I'm currently looking at e-mail security and wondered whether server to server e-mail communication that enforces TLS, will prevent the risk of TLS downgrade attacks?
2
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1answer
67 views

Why is TLS1.2 wrapped in TLS1.3?

I was just curious about TLS1.3 which Cloudflare is one of the companies leading the implementation. I then visited blog.cloudflare.com and turned on my Wireshark. I am not 100% clear about all ...
0
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2answers
181 views

How to prevent TLS downgrade on client side?

Today I noticed by experiment that Google Chrome (69.0.3497.100) and Firefox (62.0.3) both were willing to connect to a server which only supported TLS 1.0, even though the corresponding support was ...
0
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1answer
64 views

How can I know the protocol versions supported at OpenSSL1.1.0g

How can I identify the versions (TLSv1.2, TLSv1.1, TLSv1.0, SSLv3, etc.) supported in OpenSSL1.1.0g when I manually compile it from its source (NOT the one shipped with the OS like ubuntu) without ...
1
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1answer
507 views

Why would TLSv1.0 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA still be used?

First, I may be asking a dumb question. I am trying to learn, so please, take it easy on me. Second, if this is not the right place for this question, or you can link me elsewhere, please tell me/ ...
1
vote
1answer
38 views

SSL - Does Change_cipher protects against downgrade ?

An excerpt of one of my courses about SSL/TLS says the following, This excerpt is just after the Handshake finish phase of SSL (with change_cipher_spec and finished messages). Role of the finish ...
1
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1answer
130 views

Why TLS does not sign ciphersuite?

TLS negotiates a ciphersuite and TLS version to use during handshake. It confirms the handshake was not tampered with and the ciphersuite and TLS version were not downgraded using the negotiated ...
4
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2answers
773 views

What happens if STARTTLS dropped in SMTP?

SMTP uses STARTTLS extension to upgrade SMTP to SMTP Secure (STMPS). According the the RFC, the client and server starts TLS as follows: S: <waits for connection on TCP port 25> C: <opens ...
1
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1answer
446 views

What are the benefits and disadvantage of disabling <TLS1.2 client side (in browser)?

We are considering disabling TLS1.0 and TLS1.1 in the policies for a browser used organization-wide. We already have a primary browser, where >=TLS1.0 is enabled (i.e. SSLv3 is disabled). We do not ...
3
votes
1answer
145 views

Security implications of a missing SCSV, but with only TLS 1.2 allowed

Similar to this security stackexchange question, I was wondering if there's any downside, considering the services/servers security, if only TLS 1.2 allowed, but TLS Fallback Signaling Cipher Suite ...
2
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1answer
36 views

Objectives of TLS_FALL_SCSV and finished-message

I'm not sure, I can tell the purpose of a TLS_FALLBACK_SCSV. Can it prevent any attack that the finished-message can't? As far as I understand, the FIN message acts as an authentication code that ...
1
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0answers
355 views

Downgrading TLS 1.0 to SSLv3 - Handshake error (40)

I have a device that functions as a server and uses OpenSSL - it supports SSLv3 and TLS 1.0. That same device also functions as a client to some other servers - I am trying to see if I can downgrade ...
2
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1answer
7k views

How to enable ONLY TLS 1.2 in Java, blocking SSL TLS1.0 and TLS 1.1 [closed]

I'm creating my SSL context like this: SSLContext ret = SSLContext.getInstance("TLSv1.2"); When I went in firefox and forced it to disable TLS1.2, I noticed the page still loaded using TLS1.1 I ...
1
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0answers
274 views

SSLv3 downgrading attack - avoiding fallback alert

I know it won't work on every server because some don't allow SSLv3 but I tried many servers and my attack doesn't seem to work. For now, I attempt to downgrade to TLS 1.0 (also recognized by the ...
2
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1answer
657 views

Restrict cipher suites within specific protocol versions

I need to disable the weak ciphers within a weak protocol version, namely TLS1.0, on a windows server 2012 R2 running IIS. I understand that cipher suites are tied to protocol, i.e. ...
1
vote
1answer
2k views

How can an attacker downgrade/modify the cipher suites when they are MACed? (Freak, Logjam use downgrade attacks)

In the Finished handshake of TLS all previous messages exchanged are sent from the client to the server (and reverse) and protected by a MAC. This is what also "prevents" TLS_FALLBACK_SCSV from being ...
5
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1answer
4k views

Is TLS_FALLBACK_SCSV useless if only TLS (1.0, 1.1, 1.2) is supported?

Ssllabs does not give A+ (highest) rating if the server does not support TLS_FALLBACK_SCSV to prevent downgrade attack. But I am wondering, is it really any useful if the server legitimately provide ...
-4
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3answers
84 views

What is the community doing for supporting downgrading TLS? [closed]

There is not much an average end-user can do about their internet connection or available hardware/software. If you live in Kazakhstan, you'll have all https MitM'ed since 2016-01-01, since the ...
13
votes
2answers
9k views

Should I use SSL/TLS renegotiation?

Should I use SSL/TLS renegotiation? In other words: does SSL/TLS renegotiation enhance or weaken the security?