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  3. I reported an insecure DKIM key to Deutsche Telekom / T-Systems.

I reported an insecure DKIM key to Deutsche Telekom / T-Systems.

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  • dragonfrog@mastodon.sdf.orgD dragonfrog@mastodon.sdf.org

    @badkeys
    Looks like they've fixed it now (?)

    The TXT record is now
    "v=DKIM1; k=rsa; g=*; s=email; p=MEwwDQYJKoZIhvcNAQEBBQADOwAwOAIxALU5YkGFdl78dThpA8ji+/fQUxRLqG2NnZ9gILYigkIK4e/DVStSSo9MkV4DZz6RgQIDAQAB"

    I really hope they generated a new key, and didn't just switch from publishing the private key to the corresponding public one...

    millie@infosec.exchangeM This user is from outside of this forum
    millie@infosec.exchangeM This user is from outside of this forum
    millie@infosec.exchange
    wrote sidst redigeret af
    #11

    @dragonfrog @badkeys Most people might not be fluent in base64-encoded ASN.1, but a trained eye can see that it's the same key.

    Hint: A sufficiently strong RSA key cannot possibly be that short, and you know it's a DER-encoded pubkey because it starts with "ME" and ends with "AQAB" (0x10001, common RSA public exponent)

    dragonfrog@mastodon.sdf.orgD 1 Reply Last reply
    0
    • buherator@infosec.placeB buherator@infosec.place
      @badkeys My educated guess is they couldn't fit larger keys into their DNS records...
      mcr314@todon.nlM This user is from outside of this forum
      mcr314@todon.nlM This user is from outside of this forum
      mcr314@todon.nl
      wrote sidst redigeret af
      #12

      @buherator @badkeys No, they thought they were generating an ECDSA key, for which a 256 or 384 bit would be strong. But, they didn't provide the right arguments, and wound up with RSA. I think the OP posted the private key that they were able to crack trivially.

      buherator@infosec.placeB 1 Reply Last reply
      0
      • millie@infosec.exchangeM millie@infosec.exchange

        @dragonfrog @badkeys Most people might not be fluent in base64-encoded ASN.1, but a trained eye can see that it's the same key.

        Hint: A sufficiently strong RSA key cannot possibly be that short, and you know it's a DER-encoded pubkey because it starts with "ME" and ends with "AQAB" (0x10001, common RSA public exponent)

        dragonfrog@mastodon.sdf.orgD This user is from outside of this forum
        dragonfrog@mastodon.sdf.orgD This user is from outside of this forum
        dragonfrog@mastodon.sdf.org
        wrote sidst redigeret af
        #13

        @millie @badkeys
        Oh gosh, so they've removed the private key, but it's still the public key that goes with a private key that they already published.

        A sound as if a thousand faces rested in a thousand palms, and a thousand IT people sighed heavily...

        millie@infosec.exchangeM 1 Reply Last reply
        0
        • dragonfrog@mastodon.sdf.orgD dragonfrog@mastodon.sdf.org

          @millie @badkeys
          Oh gosh, so they've removed the private key, but it's still the public key that goes with a private key that they already published.

          A sound as if a thousand faces rested in a thousand palms, and a thousand IT people sighed heavily...

          millie@infosec.exchangeM This user is from outside of this forum
          millie@infosec.exchangeM This user is from outside of this forum
          millie@infosec.exchange
          wrote sidst redigeret af
          #14

          @dragonfrog @badkeys No, the private key was never published by t-systems, but it's so weak that it's very easy to crack. OP cracked and published the private key.

          dragonfrog@mastodon.sdf.orgD 1 Reply Last reply
          0
          • mcr314@todon.nlM mcr314@todon.nl

            @buherator @badkeys No, they thought they were generating an ECDSA key, for which a 256 or 384 bit would be strong. But, they didn't provide the right arguments, and wound up with RSA. I think the OP posted the private key that they were able to crack trivially.

            buherator@infosec.placeB This user is from outside of this forum
            buherator@infosec.placeB This user is from outside of this forum
            buherator@infosec.place
            wrote sidst redigeret af
            #15
            @mcr314 @badkeys Source? I doubt someone who makes a mistake like this knows what ECDSA is.
            1 Reply Last reply
            0
            • millie@infosec.exchangeM millie@infosec.exchange

              @dragonfrog @badkeys No, the private key was never published by t-systems, but it's so weak that it's very easy to crack. OP cracked and published the private key.

              dragonfrog@mastodon.sdf.orgD This user is from outside of this forum
              dragonfrog@mastodon.sdf.orgD This user is from outside of this forum
              dragonfrog@mastodon.sdf.org
              wrote sidst redigeret af
              #16

              @millie @badkeys thank you, I get it now. Iguess I'm having a slow day!

              1 Reply Last reply
              0
              • badkeys@infosec.exchangeB badkeys@infosec.exchange

                I reported an insecure DKIM key to Deutsche Telekom / T-Systems. They first asked me to further explain things (not sure why 'Here's your DKIM private key' needs more explanation, but whatever...). Then they told me it's out of scope for their bugbounty.

                I guess then there's really no reason not to tell you: They have a 384 bit RSA DKIM key configured at: dkim._domainkey.t-systems.nl

                384 bit RSA is... how shall I put it? I think 512 bit is the lowest RSA key size that was ever really used. 384 bit RSA is crackable in a few hours on a modern PC (using cado-nfs). The private key is:
                -----BEGIN RSA PRIVATE KEY-----
                MIHxAgEAAjEAtTliQYV2Xvx1OGkDyOL799BTFEuobY2dn2AgtiKCQgrh78NVK1JK
                j0yRXgNnPpGBAgMBAAECMF0t+TBZUCi8xATSMij7VLTxv5Xi5OIXesNiXOKtYIRP
                LkpYfR5PggaMScfbmqSssQIZAMwOhm9d7Y7Qi7I2j1AlYbiqdtqO54T7FQIZAONa
                9dJFkC6lM3EPXR+0SZ4dqwwpiM0nvQIYYgz8thi5JK264ohq9sTvnu9yKvUN9I09
                AhgfgMYZKcxtujRjkSZtMzUUNLYzzDmJe90CGDKwqcBI0v9ChaR8WHht+/chMdxj
                7ez94w==
                -----END RSA PRIVATE KEY-----

                irelephant@app.wafrn.netI This user is from outside of this forum
                irelephant@app.wafrn.netI This user is from outside of this forum
                irelephant@app.wafrn.net
                wrote sidst redigeret af
                #17

                @badkeys@infosec.exchange

                send an email coming from them.

                1 Reply Last reply
                0
                • kkarhan@jorts.horseK kkarhan@jorts.horse

                  @momo @badkeys sadly this is being normalized today.

                  • #Microsoft literally demands people to self-d0x or they just silently drop all eMails, even replies to their customers.
                    • And OFC neither @BNetzA nor @EUCommission did anything about this.
                  bebef@mastodon.socialB This user is from outside of this forum
                  bebef@mastodon.socialB This user is from outside of this forum
                  bebef@mastodon.social
                  wrote sidst redigeret af
                  #18

                  @kkarhan @momo @badkeys @BNetzA @EUCommission Had the same issue just recently. I wonder how this can even be legal. 🤔

                  I wanted to ask a lawyer about this, but never came around doing so.

                  yacc143@mastodon.socialY 1 Reply Last reply
                  0
                  • q@glauca.spaceQ This user is from outside of this forum
                    q@glauca.spaceQ This user is from outside of this forum
                    q@glauca.space
                    wrote sidst redigeret af
                    #19

                    @16af93 @badkeys for once, its not the Germans

                    sys64738@www.librepunk.clubS 1 Reply Last reply
                    0
                    • badkeys@infosec.exchangeB badkeys@infosec.exchange

                      I reported an insecure DKIM key to Deutsche Telekom / T-Systems. They first asked me to further explain things (not sure why 'Here's your DKIM private key' needs more explanation, but whatever...). Then they told me it's out of scope for their bugbounty.

                      I guess then there's really no reason not to tell you: They have a 384 bit RSA DKIM key configured at: dkim._domainkey.t-systems.nl

                      384 bit RSA is... how shall I put it? I think 512 bit is the lowest RSA key size that was ever really used. 384 bit RSA is crackable in a few hours on a modern PC (using cado-nfs). The private key is:
                      -----BEGIN RSA PRIVATE KEY-----
                      MIHxAgEAAjEAtTliQYV2Xvx1OGkDyOL799BTFEuobY2dn2AgtiKCQgrh78NVK1JK
                      j0yRXgNnPpGBAgMBAAECMF0t+TBZUCi8xATSMij7VLTxv5Xi5OIXesNiXOKtYIRP
                      LkpYfR5PggaMScfbmqSssQIZAMwOhm9d7Y7Qi7I2j1AlYbiqdtqO54T7FQIZAONa
                      9dJFkC6lM3EPXR+0SZ4dqwwpiM0nvQIYYgz8thi5JK264ohq9sTvnu9yKvUN9I09
                      AhgfgMYZKcxtujRjkSZtMzUUNLYzzDmJe90CGDKwqcBI0v9ChaR8WHht+/chMdxj
                      7ez94w==
                      -----END RSA PRIVATE KEY-----

                      yacc143@mastodon.socialY This user is from outside of this forum
                      yacc143@mastodon.socialY This user is from outside of this forum
                      yacc143@mastodon.social
                      wrote sidst redigeret af
                      #20

                      @badkeys
                      That was crackable with private entity resources decades ago.

                      That's not even funny.

                      1 Reply Last reply
                      0
                      • q@glauca.spaceQ q@glauca.space

                        @16af93 @badkeys for once, its not the Germans

                        sys64738@www.librepunk.clubS This user is from outside of this forum
                        sys64738@www.librepunk.clubS This user is from outside of this forum
                        sys64738@www.librepunk.club
                        wrote sidst redigeret af
                        #21

                        @q @16af93 @badkeys iirc 256-bit rsa is satcomms 'standards'

                        1 Reply Last reply
                        0
                        • badkeys@infosec.exchangeB badkeys@infosec.exchange

                          I reported an insecure DKIM key to Deutsche Telekom / T-Systems. They first asked me to further explain things (not sure why 'Here's your DKIM private key' needs more explanation, but whatever...). Then they told me it's out of scope for their bugbounty.

                          I guess then there's really no reason not to tell you: They have a 384 bit RSA DKIM key configured at: dkim._domainkey.t-systems.nl

                          384 bit RSA is... how shall I put it? I think 512 bit is the lowest RSA key size that was ever really used. 384 bit RSA is crackable in a few hours on a modern PC (using cado-nfs). The private key is:
                          -----BEGIN RSA PRIVATE KEY-----
                          MIHxAgEAAjEAtTliQYV2Xvx1OGkDyOL799BTFEuobY2dn2AgtiKCQgrh78NVK1JK
                          j0yRXgNnPpGBAgMBAAECMF0t+TBZUCi8xATSMij7VLTxv5Xi5OIXesNiXOKtYIRP
                          LkpYfR5PggaMScfbmqSssQIZAMwOhm9d7Y7Qi7I2j1AlYbiqdtqO54T7FQIZAONa
                          9dJFkC6lM3EPXR+0SZ4dqwwpiM0nvQIYYgz8thi5JK264ohq9sTvnu9yKvUN9I09
                          AhgfgMYZKcxtujRjkSZtMzUUNLYzzDmJe90CGDKwqcBI0v9ChaR8WHht+/chMdxj
                          7ez94w==
                          -----END RSA PRIVATE KEY-----

                          keksdosenmann@mastodon.socialK This user is from outside of this forum
                          keksdosenmann@mastodon.socialK This user is from outside of this forum
                          keksdosenmann@mastodon.social
                          wrote sidst redigeret af
                          #22

                          @badkeys Telekom. Die machen das.

                          christianrickert@23.socialC 1 Reply Last reply
                          0
                          • bebef@mastodon.socialB bebef@mastodon.social

                            @kkarhan @momo @badkeys @BNetzA @EUCommission Had the same issue just recently. I wonder how this can even be legal. 🤔

                            I wanted to ask a lawyer about this, but never came around doing so.

                            yacc143@mastodon.socialY This user is from outside of this forum
                            yacc143@mastodon.socialY This user is from outside of this forum
                            yacc143@mastodon.social
                            wrote sidst redigeret af
                            #23

                            @Bebef
                            It's probably not, some countries have really tough laws that they apply to email delivery and privacy that makes even spam filtering a legally dicey proposition

                            But let me put it like this, who wants to sue a company that has a legal budget bigger than the whole government budget of some of the poorer EU MS?

                            And in the end as long as the users won't start moving their fat posteriors away from the big tech monopolies, ...
                            @kkarhan @momo @badkeys @BNetzA @EUCommission

                            yacc143@mastodon.socialY 1 Reply Last reply
                            0
                            • badkeys@infosec.exchangeB badkeys@infosec.exchange

                              I reported an insecure DKIM key to Deutsche Telekom / T-Systems. They first asked me to further explain things (not sure why 'Here's your DKIM private key' needs more explanation, but whatever...). Then they told me it's out of scope for their bugbounty.

                              I guess then there's really no reason not to tell you: They have a 384 bit RSA DKIM key configured at: dkim._domainkey.t-systems.nl

                              384 bit RSA is... how shall I put it? I think 512 bit is the lowest RSA key size that was ever really used. 384 bit RSA is crackable in a few hours on a modern PC (using cado-nfs). The private key is:
                              -----BEGIN RSA PRIVATE KEY-----
                              MIHxAgEAAjEAtTliQYV2Xvx1OGkDyOL799BTFEuobY2dn2AgtiKCQgrh78NVK1JK
                              j0yRXgNnPpGBAgMBAAECMF0t+TBZUCi8xATSMij7VLTxv5Xi5OIXesNiXOKtYIRP
                              LkpYfR5PggaMScfbmqSssQIZAMwOhm9d7Y7Qi7I2j1AlYbiqdtqO54T7FQIZAONa
                              9dJFkC6lM3EPXR+0SZ4dqwwpiM0nvQIYYgz8thi5JK264ohq9sTvnu9yKvUN9I09
                              AhgfgMYZKcxtujRjkSZtMzUUNLYzzDmJe90CGDKwqcBI0v9ChaR8WHht+/chMdxj
                              7ez94w==
                              -----END RSA PRIVATE KEY-----

                              kate@mk.absturztau.beK This user is from outside of this forum
                              kate@mk.absturztau.beK This user is from outside of this forum
                              kate@mk.absturztau.be
                              wrote sidst redigeret af
                              #24

                              @badkeys@infosec.exchange ..OMFG ..​​

                              1 Reply Last reply
                              0
                              • yacc143@mastodon.socialY yacc143@mastodon.social

                                @Bebef
                                It's probably not, some countries have really tough laws that they apply to email delivery and privacy that makes even spam filtering a legally dicey proposition

                                But let me put it like this, who wants to sue a company that has a legal budget bigger than the whole government budget of some of the poorer EU MS?

                                And in the end as long as the users won't start moving their fat posteriors away from the big tech monopolies, ...
                                @kkarhan @momo @badkeys @BNetzA @EUCommission

                                yacc143@mastodon.socialY This user is from outside of this forum
                                yacc143@mastodon.socialY This user is from outside of this forum
                                yacc143@mastodon.social
                                wrote sidst redigeret af
                                #25

                                @Bebef
                                The really odd thing is it's not the oldies that nowadays are a problem, it's the youngsters, we literally had a complaint today about the PIM/office suite we use, our CEO nicely played that one. He's open to all proposals for alternatives from a company headquartered in the EEA for legal reasons.

                                Interestingly the C level has no problem IMAP, and accessing the calendar over CalDAV. But the youngsters have never heard of these @kkarhan @momo @badkeys @BNetzA @EUCommission

                                yacc143@mastodon.socialY 1 Reply Last reply
                                0
                                • yacc143@mastodon.socialY yacc143@mastodon.social

                                  @Bebef
                                  The really odd thing is it's not the oldies that nowadays are a problem, it's the youngsters, we literally had a complaint today about the PIM/office suite we use, our CEO nicely played that one. He's open to all proposals for alternatives from a company headquartered in the EEA for legal reasons.

                                  Interestingly the C level has no problem IMAP, and accessing the calendar over CalDAV. But the youngsters have never heard of these @kkarhan @momo @badkeys @BNetzA @EUCommission

                                  yacc143@mastodon.socialY This user is from outside of this forum
                                  yacc143@mastodon.socialY This user is from outside of this forum
                                  yacc143@mastodon.social
                                  wrote sidst redigeret af
                                  #26

                                  things. And are shocked that email can be provided by something else then Google, outlook or Apple. On which of these is our email hosted I was asked. I had to explain very slowly that we are on the small option "other".
                                  @kkarhan @momo @badkeys @BNetzA @EUCommission @Bebef

                                  1 Reply Last reply
                                  0
                                  • keksdosenmann@mastodon.socialK keksdosenmann@mastodon.social

                                    @badkeys Telekom. Die machen das.

                                    christianrickert@23.socialC This user is from outside of this forum
                                    christianrickert@23.socialC This user is from outside of this forum
                                    christianrickert@23.social
                                    wrote sidst redigeret af
                                    #27

                                    @keksdosenmann @badkeys

                                    Die schaffen uns. 😮‍💨

                                    1 Reply Last reply
                                    0
                                    • momo@social.linux.pizzaM momo@social.linux.pizza

                                      @badkeys
                                      Do they accept mails from noncommercial mailservers at their nl branch or do they refuse them with "554 None/Bad Reputation" as the german branch does, unless the mail admin publishes full personal (!) contact infos on a webserver hosted on the smtp machine? Just asking, because THOSE guys behave like they wrote the SMTP RFCs all by themselves...

                                      bekopharm@indieweb.socialB This user is from outside of this forum
                                      bekopharm@indieweb.socialB This user is from outside of this forum
                                      bekopharm@indieweb.social
                                      wrote sidst redigeret af
                                      #28

                                      @momo Hab mich damit auch schon herum geärgert und mit einem "Musterbrief" frei gekauft: https://beko.famkos.net/2023/06/02/%c2%b7t%c2%b7%c2%b7%c2%b7error/

                                      Die haben doch echt nicht mehr alle Latten am Zaun o0

                                      1 Reply Last reply
                                      0
                                      • kramse@helvede.netK kramse@helvede.net shared this topic
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