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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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  • 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-----

    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 last edited by
    #8
    @badkeys My educated guess is they couldn't fit larger keys into their DNS records...
    mcr314@todon.nlM 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-----

      wall_e@ioc.exchangeW This user is from outside of this forum
      wall_e@ioc.exchangeW This user is from outside of this forum
      wall_e@ioc.exchange
      wrote last edited by
      #9

      @badkeys bruh

      1 Reply Last reply
      0
      • 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 last edited by
        #10

        @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 last edited by
          #11

          @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 last edited by
            #12

            @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 last edited by
              #13

              @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 last edited by
                #14
                @mcr314 @badkeys Source? I doubt someone who makes a mistake like this knows what ECDSA is.
                J 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 last edited by
                  #15

                  @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 last edited by
                    #16

                    @badkeys@infosec.exchange

                    send an email coming from them.

                    1 Reply Last reply
                    0
                    • K 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 last edited by
                      #17

                      @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.

                      K yacc143@mastodon.socialY stellated@mastodon.sdf.orgS 3 Replies Last reply
                      0
                      • R relay@relay.mycrowd.ca shared this topic
                      • q@glauca.spaceQ q@glauca.space

                        @badkeys You thought 384-bit was bad? I recently found a live, in daily use, 256-bit key in a, shall we say, large government entity that should know better (would rather not say much more publicly as its relevant to a paper under submission).

                        16af93@wetdry.world1 This user is from outside of this forum
                        16af93@wetdry.world1 This user is from outside of this forum
                        16af93@wetdry.world
                        wrote last edited by
                        #18

                        @q @badkeys BSI at it again?

                        q@glauca.spaceQ T 2 Replies Last reply
                        0
                        • 16af93@wetdry.world1 16af93@wetdry.world

                          @q @badkeys BSI at it again?

                          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 last edited by
                          #19

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

                          16af93@wetdry.world1 sys64738@www.librepunk.clubS 2 Replies Last reply
                          0
                          • q@glauca.spaceQ q@glauca.space

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

                            16af93@wetdry.world1 This user is from outside of this forum
                            16af93@wetdry.world1 This user is from outside of this forum
                            16af93@wetdry.world
                            wrote last edited by
                            #20

                            @q @badkeys

                            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 last edited by
                              #21

                              @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
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                                sys64738@www.librepunk.club
                                wrote last edited by
                                #22

                                @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-----

                                  tanja@mastodon.catgirl.cloudT This user is from outside of this forum
                                  tanja@mastodon.catgirl.cloudT This user is from outside of this forum
                                  tanja@mastodon.catgirl.cloud
                                  wrote last edited by
                                  #23

                                  @badkeys@infosec.exchange oooofffff

                                  But why would they turn down the bug bounty????

                                  <img class="not-responsive emoji" src="https://content.mastodon.catgirl.cloud/custom_emojis/images/000/055/198/original/neocat_googly_shocked.png" title=":neocat_googly_shocked:" />

                                  oscherler@tooting.chO 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-----

                                    jane@smolhaj.socialJ This user is from outside of this forum
                                    jane@smolhaj.socialJ This user is from outside of this forum
                                    jane@smolhaj.social
                                    wrote last edited by
                                    #24

                                    @networkexception Now I want T-Systems involved into Synapse Pro development. Have an ISP approved way when your matrix message "is not decryptable" to decrypt it after a few hours of compute time. It's not a bug, it's a feature they provide if their bug bounty rejects this.

                                    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-----

                                      lunareclipse@snug.moeL This user is from outside of this forum
                                      lunareclipse@snug.moeL This user is from outside of this forum
                                      lunareclipse@snug.moe
                                      wrote last edited by
                                      #25

                                      @badkeys bad companies that don't pay out bug bounties can have uncoordinated public disclosure as a treat :3

                                      kbruen@procial.tchncs.deK yama@tech.lgbtY 2 Replies Last reply
                                      1
                                      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 last edited by
                                        #26

                                        @badkeys Telekom. Die machen das.

                                        christianrickert@23.socialC 1 Reply Last reply
                                        1
                                        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.

                                          K This user is from outside of this forum
                                          K This user is from outside of this forum
                                          kkarhan@jorts.horse
                                          wrote last edited by
                                          #27

                                          @Bebef @momo @badkeys Neither did I.

                                          And the next-best qualified lawyer I'd know in that part is @wbs_legal.

                                          • Sadly there's no legal precedent to establish the same "duty to deliver" as with #PostalOperators which ain't allowed to do anything unless explicitly instructed by the reciever or served a warrant by a judge.
                                            • And obviously regulators like @BNetzA & @EUCommission likely ain't even aware of this issue since #ConsumerProtection doesn't apply to #SmallBusinesses!
                                          1 Reply Last reply
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