August 2020 - dovecot

CVE-2020-12100: Receiving mail with deeply nested MIME parts leads to resource exhaustion.
by Aki Tuomi 12 Aug '20

12 Aug '20

Open-Xchange Security Advisory 2020-08-12 Affected product: Dovecot IMAP server Internal reference: DOP-1849 (Bug ID) Vulnerability type: Uncontrolled recursion (CWE-674) Vulnerable version: 2.0 Vulnerable component: submission, lmtp, lda Fixed version: 2.3.11.3 Report confidence: Confirmed Solution status: Fix available Vendor notification: 2020-04-23 CVE reference: CVE-2020-12100 CVSS: 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) Vulnerability Details: Receiving mail with deeply nested MIME parts leads to resource exhaustion as Dovecot attempts to parse it. Risk: Malicious actor can cause denial of service to mail delivery by repeatedly sending mails with bad content. Workaround: Limit MIME structures in MTA. Solution: Upgrade to fixed version. Best regards, Aki Tuomi Open-Xchange oy

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Dovecot v2.3.11.3 released
by Aki Tuomi 12 Aug '20

12 Aug '20

We are pleased to release v2.3.11.3. Please find it from locations below: https://dovecot.org/releases/2.3/dovecot-2.3.11.3.tar.gz https://dovecot.org/releases/2.3/dovecot-2.3.11.3.tar.gz.sig Binary packages in https://repo.dovecot.org/ Docker images in https://hub.docker.com/r/dovecot/dovecot Aki Tuomi Open-Xchange oy --- * CVE-2020-12100: Parsing mails with a large number of MIME parts could have resulted in excessive CPU usage or a crash due to running out of stack memory. * CVE-2020-12673: Dovecot's NTLM implementation does not correctly check message buffer size, which leads to reading past allocation which can lead to crash. * CVE-2020-10967: lmtp/submission: Issuing the RCPT command with an address that has the empty quoted string as local-part causes the lmtp service to crash. * CVE-2020-12674: Dovecot's RPA mechanism implementation accepts zero-length message, which leads to assert-crash later on. * Events: Fix inconsistency in events. See event documentation in https://doc.dovecot.org. * imap_command_finished event's cmd_name field now contains "unknown" for unknown commands. A new "cmd_input_name" field contains the command name exactly as it was sent. * lib-index: Renamed mail_cache_compress_* settings to mail_cache_purge_*. Note that these settings are mainly intended for testing and usually shouldn't be changed. * events: Renamed "index" event category to "mail-index". * events: service:<name> category is now using the name from configuration file. * dns-client: service dns_client was renamed to dns-client. * log: Prefixes generally use the service name from configuration file. For example dict-async service will now use "dict-async(pid): " log prefix instead of "dict(pid): " * *-login: Changed logging done by proxying to use a consistent prefix containing the IP address and port. * *-login: Changed disconnection log messages to be slightly clearer. + dict: Add events for dictionaries. + lib-index: Finish logging with events. + oauth2: Support local validation of JWT tokens. + stats: Add support for dynamic histograms and grouping. See https://doc.dovecot.org/configuration_manual/stats/. + imap: Implement RFC 8514: IMAP SAVEDATE + lib-index: If a long-running transaction (e.g. SORT/FETCH on a huge folder) adds a lot of data to dovecot.index.cache file, commit those changes periodically to make them visible to other concurrent sessions as well. + stats: Add OpenMetrics exporter for statistics. See https://doc.dovecot.org/configuration_manual/stats/openmetrics/. + stats: Support disabling stats-writer socket by setting stats_writer_socket_path="". - auth-worker: Process keeps slowly increasing its memory usage and eventually dies with "out of memory" due to reaching vsz_limit. - auth: Prevent potential timing attacks in authentication secret comparisons: OAUTH2 JWT-token HMAC, imap-urlauth token, crypt() result. - auth: Several auth-mechanisms allowed input to be truncated by NUL which can potentially lead to unintentional issues or even successful logins which should have failed. - auth: When auth policy returned a delay, auth_request_finished event had policy_result=ok field instead of policy_result=delayed. - auth: auth process crash when auth_policy_server_url is set to an invalid URL. - auth: Lua passdb/userdb leaks stack elements per call, eventually causing the stack to become too deep and crashing the auth or auth-worker process. - dict-ldap: Crash occurs if var_expand template expansion fails. - dict: If dict client disconnected while iteration was still running, dict process could have started using 100% CPU, although it was still handling clients. - doveadm: Running doveadm commands via proxying may hang, especially when doveadm is printing a lot of output. - imap: "MOVE * destfolder" goes to a loop copying the last mail to the destination until the imap process dies due to running out of memory. - imap: Running "UID MOVE 1:* Trash" on an empty folder goes to infinite loop. - imap: SEARCH doesn't support $. - lib-compress: Buffer over-read in zlib stream read. - lib-dns: If DNS lookup times out, lib-dns can cause crash in calling process. - lib-index: Fixed several bugs in dovecot.index.cache handling that could have caused cached data to be lost. - lib-index: Writing to >=1 GB dovecot.index.cache files may cause assert-crashes: Panic: file mail-index-util.c: line 37 (mail_index_uint32_to_offset): assertion failed: (offset < 0x40000000) - lib-mail: v2.3.11 regression: MIME parts not returned correctly by Dovecot MIME parser. - lib-ssl-iostream: Fix buggy OpenSSL error handling without assert-crashing. If there is no error available, log it as an error instead of crashing: Panic: file iostream-openssl.c: line 599 (openssl_iostream_handle_error): assertion failed: (errno != 0) - lib-ssl-iostream: ssl_key_password setting did not work. - pop3-login: Login didn't handle commands in multiple IP packets properly. This mainly affected large XCLIENT commands or a large SASL initial response parameter in the AUTH command. - pop3: pop3_deleted_flag setting was broken, causing: Panic: file seq-range-array.c: line 472 (seq_range_array_invert): assertion failed: (range[count-1].seq2 <= max_seq) - pop3-login: Login would fail with "Input buffer full" if the initial response for SASL was too long. - submission: A segfault crash may occur when the client or server disconnects while a non-transaction command like NOOP or VRFY is still being processed. - virtual: Copying/moving mails with IMAP into a virtual folder assert-crashes: Panic: file cmd-copy.c: line 152 (fetch_and_copy): assertion failed: (copy_ctx->copy_count == seq_range_count(&copy_ctx->saved_uids))

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Client shows incorrect message counts
by Antonio Leding 11 Aug '20

11 Aug '20

Hello all… First, a disclaimer…I am aware that this is very likely not a Dovecot related issue but I am truly pulling whatever hair I have left out of my head and given the brain-power of this mailer, I thought someone might know what is going in here. The issues is this… I check the message counts for a given account using doveadm and get a given number. I then configure the same account in 3 mail clients: Apple Mail, Mailmate, and Thunderbird. Both the Mailmate and Thunderbird message counts match exactly with the doveadm numbers. Apple Mail is low in almost all cases. I have tried every idea I have found including: — Delete and recreate the mail account — Rebuild mailbox — Resync mailbox — Reindex Spotlight — Removing the "~/Library/Mail/V*/Envelope*” files; restart Mail — Remove the entire "~/Library/Mail/V*” directory; restart Mail So, at wit’s end and again, apologies for this not being a Dovecot-centric issue but I know you are all on top of this stuff and may have an idea… Thanks in advance...

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Thanks, got replys
by Chris Bennett 11 Aug '20

11 Aug '20

I've got a mix of some receive only, some send only. I tried to slam together two different configs really fast. This helped. I'll look things over and post some configs after a bit. Thanks again! Chris Bennett

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Test on sending only
by Chris Bennett 10 Aug '20

10 Aug '20

I had to move off of a server to this one too fast. Having problems If this goes through, if someone could reply to chris(a)bennettconstruction.us instead of on-list. Thanks, Chris Bennett

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IMAP Permissions per IP
by Jorge Bastos 10 Aug '20

10 Aug '20

Howdy, Is it possible to define IMAP permissions per IT? What i would like to do is: * IP 1.1.1.1 IS THE ONLY ONE that has permission for EXPUNGE Is it possible? Thanks in advanced,

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is there a way to run doveadm expunge with exception?
by teacup 09 Aug '20

09 Aug '20

is there a way to run this command but with exception to not delete the FLAGGED email? doveadm expunge -u user(a)email.com mailbox Inbox SENTBEFORE 90d -- Sent from: http://dovecot.2317879.n4.nabble.com/

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IPv6 auth failed
by Lefteris Tsintjelis 09 Aug '20

09 Aug '20

I am using latest Windows Thunderbird 68.11.0 and dovecot 2.3.10.1_2 with FreeBSD 12.1-RELEASE-p8. Whenever I enable dovecot IPv6 and I try to login I get auth failed. Aug 09 08:36:11 imap-login: Info: Disconnected: Inactivity (auth failed, 2 attempts in 180 secs): user=<user(a)domain.com>, method=CRAM-MD5, rip=1:2:3:4::5, lip=1:2:3:6::7, TLS, session=<HZeFLGusb8IgAQZ8LNQAEgAAAAAAAAAC> Switching dovecot back to IPv4 only (listen = *) starts to work as expected. Roundcube seems to also have the same problem whenever dovecot IPv6 is enabled.

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Re: [EXT] Re: mail_crypt folder keys without sql database
by Aki Tuomi 06 Aug '20

06 Aug '20

> On 06/08/2020 13:52 secure.light.0417.road <secure.light.0417.road(a)protonmail.com> wrote: > > > Ah, right. The hashed password can't be used to encrypt. > > I want to remove possibility to decrypt mails using materials in mail servers in VPS. I've thought about below scenario: > > 1. The client generates asymmetric keys in local. > 2. The client sends the public key to the dovecot in the mail server. > 3. The dovecot generates a symmetric key. > 4. The dovecot encrypts a received mail with the symmetric key. > 5. The dovecot also encrypts the symmetric key with the public key. > 6. The client get the mail and encrypted symmetric key from server into local and decrypts it using local private key. > You probably want to use PGP then. > Instead of 1 and 2, the way like "the dovecot generates all 3 and removes only private key", can be considered with docker image deployment. mail_crypt plugin is primarily intended to protect storage medium, and not end user as such. While it does support this, it's not perfect tool for it, and can be bit difficult to set up. Dovecot does not support client-supplied private keys. > > Is it possible with mail_crypt? > > narangd > Aki p.s. please keep responses on the list.

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Re: [EXT] Re: mail_crypt folder keys without sql database
by Aki Tuomi 06 Aug '20

06 Aug '20

mail_crypt_private_password cannot be hashed, as it's used to encrypt the key. Aki > On 06/08/2020 10:06 secure.light.0417.road <secure.light.0417.road(a)protonmail.com> wrote: > > > I've tried to append the field "userdb_mail_crypt_private_password=<same-hashed-password-in-passwd-file>" to the end of each user line in userdb as passwd-file. And use the command below to generate keys. > > doveadm -o plugin/mail_crypt_private_password=<not-hashed-user-password> mailbox cryptokey generate -u <username> -U > > I confirmed mail encryption work properly. > > Also I've compared two "dovecot-attribute" files with and without "mail_crypt_require_encrypted_user_key = yes". Seemingly they have no difference. How to check that the private key in dovecot-attribute be encrypted properly? > > narangd > > Sent with ProtonMail Secure Email. > > ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ > On Thursday, August 6, 2020 1:03 AM, Aki Tuomi <aki.tuomi(a)open-xchange.com> wrote: > > > > On 05/08/2020 18:45 secure.light.0417.road secure.light.0417.road(a)protonmail.com wrote: > > > Hello, > > > Can the mail_crypt "folder keys" feature be used with encrypted user keys in passwd-file without sql database? It seems that there is no guide in the docs. > > > Best regards, > > > narangd > > > > Dovecot stores folder and user keys into mail_attribute_dict. This does not have to be SQL database. > > > > You can also add `userdb_mail_crypt_private_password` into passwd-file to provide it if you use passwd-file as userdb. > > > > Aki

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