- dovecot - dovecot.org

under some kind of attack
by mj 21 Jul '17

21 Jul '17

Hi all, It seems we are under some kind of password guessing attack: > Jul 18 21:33:33 auth: Info: ldap(username1,103.6.223.61,<W7wLl5xUfABnBt89>): invalid credentials (given password: 1q2w3e4r5t) > Jul 18 21:34:16 auth: Info: ldap(username1,221.4.61.180,<89WnmZxUrADdBD20>): invalid credentials (given password: 1q2w3e4r5t) > Jul 18 21:36:13 auth: Info: ldap(username2,117.243.180.225,<ESWBoJxUdQB187Th>): invalid credentials (given password: 1q2w3e4r) > Jul 18 21:36:50 auth: Info: ldap(username2,58.59.103.230,<j7fQopxUNgA6O2fm>): invalid credentials (given password: 1q2w3e4r) > Jul 18 21:36:56 auth: Info: ldap(username4,58.215.13.154,<gtY5o5xUlQA61w2a>): invalid credentials (given password: 1q2w3e4r5t) > Jul 18 21:37:18 auth: Info: ldap(username3,220.175.154.205,<lFxppJxUFADcr5rN>): invalid credentials (given password: 1q2w3e4r) > Jul 18 21:37:25 auth: Info: ldap(username5,14.142.29.142,<40zopJxUSgAOjh2O>): invalid credentials (given password: 1q2w3e4r) > Jul 18 21:37:27 auth: Info: ldap(username4,119.1.98.121,<JDQOpZxUCwB3AWJ5>): invalid credentials (given password: 1q2w3e4r5t) > Jul 18 21:37:54 auth: Info: ldap(username3,218.76.156.11,<OMqtppxUMADaTJwL>): invalid credentials (given password: 1q2w3e4r) Different IPs, different usernames, but all (almost) the same password. Any idea what we can do about this?? Any advice you could give us would be very much appreciated. MJ

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application specific passwords
by mj 21 Jul '17

21 Jul '17

Hi, Further to the other thread about password guessing activities against our dovecot, I would like to implement application specific passwords on our dovecot. Googling results in some documents, but they are all a bit older: > https://www.happyassassin.net/2014/08/26/adding-application-specific-passwo… > https://www.dgsiegel.net/news/2013_05_21-application_specific_passwords_for… > http://www.justinbuchanan.com/blog/category/RoundCube > http://www.justinbuchanan.com/blog/post/2012/12/02/Application-Specific-Pas… Those articles are interesting, but also rather old. (I realse that this does not neccesarily mean: irrelevant or bad) Is there anone here with some additional notes, ideas, tips, trics on setting up application specific passwords with dovecot with virtual users? We are using samba AD as an authentication backend. MJ

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Re: under some kind of attack
by Joseph Tam 21 Jul '17

21 Jul '17

> I would like to create a fail2ban filer, that scans for these lines: > >> Jul 20 11:10:09 auth: Info: ldap(user1,60.166.35.162,<cDFXHbxUQgA8piOi>): invalid credentials (given password: password) >> Jul 20 11:10:19 auth: Info: ldap(user2,61.53.66.4,<V+nyHbxU+wA9NUIE>): invalid credentials (given password: password) > > (as you can see, I have enabled auth_verbose_passwords to do this, > making me very uncomfortable...) > > Anyway: since there are only a few password variations, I would like to > block anyone using those passwords. With all the constraints and processing, I'll offer yet another option: use the checkpassword password authentication scheme. This will bypass post-authentcation log-sniffing and allow you direct access to username, password and client IP (the last I'm not positive about) at authentication time. Now you'll have everything you need to do any wild and crazy auth processing, including database searches and triggering firewall blocking based on whatever crietria you want (including common password use). As to how to integrate it into your dovecot, I'm not sure whether it's best to supplant the LDAP method and authenticate within the checkpassword script, or to put it as the first authentication method (ahead of LDAP) to get first crack at inspect at authentication data, or the fallback authentication method (after LDAP) to pick up all the failures. However, after running honeypots, I can tell you that although BFD attackers will common use passwords, any static list of abused passwords will miss a lot. (A common one they use is $password=variations($user) or variation($domain)). Number of auth failure limits should also be a criteria for banning. Extinct users are also good candidates for instant banning. Joseph Tam <jtam.home(a)gmail.com>

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2.2.devel (0bee280) crashdump virtual plugin
by Thomas Leuxner 20 Jul '17

20 Jul '17

#0 0x00007f497ecdb067 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56 resultvar = 0 pid = 10092 selftid = 10092 #1 0x00007f497ecdc448 in __GI_abort () at abort.c:89 save_stage = 2 act = {__sigaction_handler = {sa_handler = 0xfffe, sa_sigaction = 0xfffe}, sa_mask = {__val = {1024, 140722499998576, 94791001010256, 513, 139953641023651, 140722499998368, 94791001010256, 513, 11573297580199803136, 139953644744448, 139953641204307, 94791001010256, 140722499998464, 0, 139953641204665, 94791001010256}}, sa_flags = 2131669786, sa_restorer = 0x7ffc829fd301} sigs = {__val = {32, 0 <repeats 15 times>}} #2 0x00007f497f0f05b6 in default_fatal_finish (type=<optimized out>, status=status@entry=0) at failures.c:201 backtrace = 0x56363ff17088 "/usr/lib/dovecot/libdovecot.so.0(+0x9f5be) [0x7f497f0f05be] -> /usr/lib/dovecot/libdovecot.so.0(+0x9f6ac) [0x7f497f0f06ac] -> /usr/lib/dovecot/libdovecot.so.0(i_fatal+0) [0x7f497f080fde] -> /usr/lib/d"... #3 0x00007f497f0f06ac in i_internal_fatal_handler (ctx=0x7ffc829fd350, format=<optimized out>, args=<optimized out>) at failures.c:670 status = 0 #4 0x00007f497f080fde in i_panic (format=format@entry=0x7f497f47af00 "file %s: line %d (%s): assertion failed: (%s)") at failures.c:275 ctx = {type = LOG_TYPE_PANIC, exit_status = 0, timestamp = 0x0, timestamp_usecs = 0} args = {{gp_offset = 40, fp_offset = 48, overflow_arg_area = 0x7ffc829fd450, reg_save_area = 0x7ffc829fd390}} #5 0x00007f497f3cb6dc in mailbox_notify_changes_stop (box=<optimized out>) at mail-storage.c:1950 __FUNCTION__ = "mailbox_notify_changes_stop" #6 0x00007f497dc5aa6f in virtual_notify_changes (box=0x5636400cdbd8) at virtual-storage.c:696 bboxp_end = 0x563640015708 mbox = 0x5636400cdbd8 bboxp = 0x563640015180 #7 0x000056363f5e2652 in idle_finish (ctx=ctx@entry=0x56363ff64160, done_ok=<optimized out>, free_cmd=free_cmd@entry=true) at cmd-idle.c:46 client = 0x56363ff39e68 #8 0x000056363f5e2783 in idle_client_handle_input (ctx=ctx@entry=0x56363ff64160, free_cmd=free_cmd@entry=true) at cmd-idle.c:67 line = <optimized out> #9 0x000056363f5e284d in idle_client_input_more (ctx=0x56363ff64160) at cmd-idle.c:100 client = 0x56363ff39e68 #10 idle_client_input (ctx=0x56363ff64160) at cmd-idle.c:107 client = 0x56363ff39e68 #11 0x00007f497f105b22 in io_loop_call_io (io=0x56363ffae400) at ioloop.c:599 ioloop = 0x56363ff1f9b0 t_id = 2 __FUNCTION__ = "io_loop_call_io" #12 0x00007f497f10717a in io_loop_handler_run_internal (ioloop=ioloop@entry=0x56363ff1f9b0) at ioloop-epoll.c:223 ctx = 0x56363ff214d0 io = <optimized out> tv = {tv_sec = 3, tv_usec = 496715} events_count = <optimized out> msecs = <optimized out> ret = 1 i = 0 j = <optimized out> call = <optimized out> __FUNCTION__ = "io_loop_handler_run_internal" #13 0x00007f497f105bbc in io_loop_handler_run (ioloop=ioloop@entry=0x56363ff1f9b0) at ioloop.c:648 No locals. #14 0x00007f497f105d68 in io_loop_run (ioloop=0x56363ff1f9b0) at ioloop.c:623 __FUNCTION__ = "io_loop_run" #15 0x00007f497f08b6d3 in master_service_run (service=0x56363ff1f850, callback=<optimized out>) at master-service.c:666 No locals. #16 0x000056363f5de1d3 in main (argc=1, argv=0x56363ff1f5e0) at main.c:491 set_roots = {0x56363f8096c0 <imap_setting_parser_info>, 0x7f497f8d5540 <lda_setting_parser_info>, 0x0} login_set = {auth_socket_path = 0x56363ff17048 "\001", postlogin_socket_path = 0x0, postlogin_timeout_secs = 60, callback = 0x56363f5f92b0 <login_client_connected>, failure_callback = 0x56363f5f8bf0 <login_client_failed>, request_auth_token = 1} service_flags = <optimized out> storage_service_flags = <optimized out> username = 0x0 auth_socket_path = 0x56363f602074 "auth-master" c = <optimized out>

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SRS and vacation message
by Kacper Guzik 20 Jul '17

20 Jul '17

Hi i have similiar problem like here: http://www.iredmail.org/forum/topic11833-iredmail-support-vocation-respone-… email send : from : web123(a)gmail.com to : jacka(a)mail.com vocation sent back from : jacka(a)mail.com to : srs0=hmc8=v7=gmail.com=web123(a)mail.com postsrsd changing return-path from web123(a)gmail.com to srs0=hmc8=v7= gmail.com=web123(a)mail.com this is no problem for me but sieve: Vacation's messages are always addressed to the Return-Path address it is possible some how change this ugly to header to normal? dovecot --version 2.2.29.1 (e0b76e3) # 2.2.29.1 (e0b76e3): /usr/local/etc/dovecot/dovecot.conf # Pigeonhole version 0.4.18 (29cc74d) doveconf: Warning: service auth { client_limit=125000 } is lower than required under max. load (150000) # OS: Linux 3.10.0-514.16.1.el7.x86_64 x86_64 CentOS Linux release 7.3.1611 (Core) auth_master_user_separator = * auth_mechanisms = plain login auth_worker_max_count = 60 default_client_limit = 125000 default_process_limit = 25000 dict { quotadict = mysql:/etc/dovecot/dovecot-used-quota.conf } disable_plaintext_auth = no listen = * log_path = /var/log/dovecot.log login_trusted_networks = xxx mail_fsync = never mail_gid = 2000 mail_location = maildir:/%Lh/Maildir/:INDEX=/%Lh/Maildir/ mail_max_userip_connections = 128 mail_plugins = quota zlib expire mail_uid = 2000 maildir_broken_filename_sizes = yes managesieve_notify_capability = mailto managesieve_sieve_capability = fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify environment mailbox date ihave namespace inbox { inbox = yes location = mailbox Drafts { auto = subscribe special_use = \Drafts } mailbox Junk { auto = subscribe autoexpunge = 30 days special_use = \Junk } mailbox Sent { auto = subscribe special_use = \Sent } mailbox Trash { auto = subscribe autoexpunge = 30 days special_use = \Trash } prefix = } passdb { args = /etc/dovecot/dovecot-mysql.conf driver = sql } plugin { acl = vfile acl_shared_dict = proxy::acl auth_socket_path = /var/run/dovecot/auth-master quota = dict:user::proxy::quotadict sieve = /home/sieve/%Ld/%Ln/dovecot.sieve sieve_after = /home/sieve/dovecot.sieve sieve_default = /home/sieve/dovecot.sieve sieve_dir = /home/sieve/%Ld/%Ln sieve_global_dir = /home/sieve sieve_global_path = /home/sieve/dovecot.sieve sieve_max_redirects = 25 zlib_save = gz zlib_save_level = 9 } protocols = pop3 imap sieve lmtp service auth { service_count = 0 unix_listener auth-master { group = vmail mode = 0666 user = vmail } unix_listener auth-userdb { group = vmail mode = 0660 user = vmail } } service dict { unix_listener dict { group = vmail mode = 0777 user = vmail } } service imap-login { process_min_avail = 16 service_count = 0 vsz_limit = 64 M } service imap { process_limit = 4096 } service lmtp { executable = lmtp -L inet_listener lmtp { port = 24 } user = vmail } service pop3-login { process_min_avail = 16 service_count = 0 } service quota-warning { executable = script /usr/local/bin/dovecot-quota-warning.sh unix_listener quota-warning { group = root mode = 0666 user = root } user = root } ssl_ca = </etc/ssl/ca-bundle.crt ssl_cert = </etc/ssl/xxx.crt ssl_key = # hidden, use -P to show it submission_host = xxx userdb { args = /etc/dovecot/dovecot-mysql.conf driver = sql } protocol imap { imap_client_workarounds = tb-extra-mailbox-sep mail_plugins = quota imap_quota mail_log notify zlib } protocol pop3 { mail_plugins = quota zlib expire pop3_client_workarounds = outlook-no-nuls oe-ns-eoh pop3_uidl_format = %08Xu%08Xv } protocol lmtp { info_log_path = /var/log/dovecot-lmtp.log mail_fsync = optimized mail_plugins = quota sieve zlib postmaster_address = xxx } remote xxx { mail_max_userip_connections = 51200 }

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Dovecot imap
by nlekkas＠gmail.com 20 Jul '17

20 Jul '17

Hello there to all ! Here is the doveconf - a as asked by Aki Tuomi.. Do you see anything wrong..? I would appreciate mush in anyone could help ... # OS: Linux 2.6.32-696.1.1.el6.x86_64 x86_64 CentOS release 6.9 (Final) auth_mechanisms = plain login disable_plaintext_auth = no mail_location = maildir:~/Maildir mail_plugins = " quota" mbox_write_locks = fcntl passdb { driver = pam } plugin { quota = fs:User quota quota_grace = 10%% quota_status_nouser = DUNNO quota_status_overquota = 552 5.2.2 Mailbox is full quota_status_success = DUNNO } protocols = imap pop3 userdb { driver = passwd } protocol imap { mail_plugins = " quota imap_quota" } protocol pop3 { pop3_uidl_format = %08Xu%08Xv }

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Re: under some kind of attack
by Joseph Tam 20 Jul '17

20 Jul '17

mj <lists(a)merit.unu.edu> writes: >>> However, it seems almost all IPs are different, and I don't think I can >>> keep the above settings permanently. >> >> Why not? Limited by firewall rules overload? You could probably use >> a persistent DB, can't you? > > I meant: keep the "block after the first failed attempt" setting. People > need the chance to change their password, so I have increased it to two. A timeout feature is handy here; even though you allow attackers several kicks at the can, it will allow your users to eventually gain control to their accounts again after a suitable penalty period. >> You can also use a third party RBL that specialized in brute forcers like >> blocklist.de. You can also feed back fail2ban data and crowdsource BFD >> data to them. > > Yes, I will look into that now. > ... > > Anyone aware of other blocklists that are worth bocking? Because the > list.blocklist.de/lists/all.txt blocks some, but not anywhere near all. There are other RBLs that overlap with this (like CBL), but they include entries will produce false positives. There was OpenBL but that is defunct. The different lists at blocklist.de have varying efficacy: the ssh and smtp BFD detection are fairly good (they have a 90+% hit rate at my site), but the IMAP/POP BFD detection not as good (maybe 20%). However, if people start feeding IMAP/POP fail2ban data back to blocklist.de, that will get better. > I now know how to block large lists of ips, so if anyone has additional > lists to block? Yeah, all of ChinaNet. May produce false positives. Joseph Tam <jtam.home(a)gmail.com>

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Dovecot imap
by Nick Lekkas 19 Jul '17

19 Jul '17

Hello there ! Is there anything wrong in the config i have sent earlier ..? __________ Information from ESET Endpoint Antivirus, version of detection engine 15774 (20170719) __________ The message was checked by ESET Endpoint Antivirus. Email message - is OK http://www.eset.com

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Re: under some kind of attack
by Joseph Tam 19 Jul '17

19 Jul '17

On Tue, 18 Jul 2017, dovecot-request(a)dovecot.org wrote: > Thanks for the quick follow-ups! Much appreciated. After posting this, I > immediately started working on fail2ban. And between my initial posting > and now, fail2ban already blocked 114 IPs. > > I have fail2ban with maxretry=1 and bantime=1800 > > However, it seems almost all IPs are different, and I don't think I can > keep the above settings permanently. Why not? Limited by firewall rules overload? You could probably use a persistent DB, can't you? You can also use a third party RBL that specialized in brute forcers like blocklist.de. You can also feed back fail2ban data and crowdsource BFD data to them. Joseph Tam <jtam.home(a)gmail.com>

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Dovecot imap
by Nick Lekkas 19 Jul '17

19 Jul '17

Hello to all !!! I have some issues with some users that login to the same account through imap from many devices like: mobile,desktop/tablet !!! Issues like: 1. When a new email is arrived is not appearing to all devices... 2. New email is arriving to some other devices after a long period of time ... Generally issues like that .... Does anyone have an idea of how to solve this ..? thanks in advance for your time ... __________ Information from ESET Endpoint Antivirus, version of virus signature database 14893 (20170206) __________ The message was checked by ESET Endpoint Antivirus. Email message - is OK http://www.eset.com __________ Information from ESET Endpoint Antivirus, version of virus signature database 14911 (20170209) __________ The message was checked by ESET Endpoint Antivirus. Email message - is OK http://www.eset.com __________ Information from ESET Endpoint Antivirus, version of virus signature database 14939 (20170215) __________ The message was checked by ESET Endpoint Antivirus. Email message - is OK http://www.eset.com __________ Information from ESET Endpoint Antivirus, version of virus signature database 14964 (20170220) __________ The message was checked by ESET Endpoint Antivirus. Email message - is OK http://www.eset.com __________ Information from ESET Endpoint Antivirus, version of virus signature database 15008 (20170228) __________ The message was checked by ESET Endpoint Antivirus. Email message - is OK http://www.eset.com __________ Information from ESET Endpoint Antivirus, version of virus signature database 15037 (20170305) __________ The message was checked by ESET Endpoint Antivirus. Email message - is OK http://www.eset.com __________ Information from ESET Endpoint Antivirus, version of detection engine 15767 (20170718) __________ The message was checked by ESET Endpoint Antivirus. Email message - is OK http://www.eset.com __________ Information from ESET Endpoint Antivirus, version of detection engine 15767 (20170718) __________ The message was checked by ESET Endpoint Antivirus. Email message - is OK http://www.eset.com

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