From 8614ca8c41a0d868f0d54d219666374216fb70d4 Mon Sep 17 00:00:00 2001 From: Shane Forsythe <2287983+shaneforsythe@users.noreply.github.com> Date: Tue, 2 Oct 2018 17:24:33 -0400 Subject: [PATCH 1/2] Update proftpd.conf proftpd 1.3.5e can leave inconsistent error message if ftp or mod_sftp is used Oct 2 15:45:31 ftp01 proftpd[5516]: 10.10.2.13 (10.10.2.189[10.10.2.189]) - SECURITY VIOLATION: Root login attempted Oct 2 15:45:44 ftp01 proftpd[5517]: 10.10.2.13 (10.10.2.189[10.10.2.189]) - SECURITY VIOLATION: Root login attempted. Fix regex to make trailing period optional, otherwise brute force attacks against root account using ftp are not blocked correctly. --- config/filter.d/proftpd.conf | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/config/filter.d/proftpd.conf b/config/filter.d/proftpd.conf index 303be5e5..feb59f11 100644 --- a/config/filter.d/proftpd.conf +++ b/config/filter.d/proftpd.conf @@ -18,7 +18,7 @@ __suffix_failed_login = (User not authorized for login|No such user found|Incorr failregex = ^%(__prefix_line)s%(__hostname)s \(\S+\[\]\)[: -]+ USER .*: no such user found from \S+ \[\S+\] to \S+:\S+ *$ ^%(__prefix_line)s%(__hostname)s \(\S+\[\]\)[: -]+ USER .* \(Login failed\): %(__suffix_failed_login)s\s*$ - ^%(__prefix_line)s%(__hostname)s \(\S+\[\]\)[: -]+ SECURITY VIOLATION: .* login attempted\. *$ + ^%(__prefix_line)s%(__hostname)s \(\S+\[\]\)[: -]+ SECURITY VIOLATION: .* login attempted\.? *$ ^%(__prefix_line)s%(__hostname)s \(\S+\[\]\)[: -]+ Maximum login attempts \(\d+\) exceeded *$ ignoreregex = From 606bf110c99c0b491b10f336b67675311f279f1a Mon Sep 17 00:00:00 2001 From: sebres Date: Mon, 16 Mar 2020 17:29:09 +0100 Subject: [PATCH 2/2] filter.d/sshd.conf (mode `ddos`): fixed "connection reset" regex (seems to have same syntax now as closed), so both regex's combined now to single RE (closes gh-2662) --- config/filter.d/sshd.conf | 3 +-- .../tests/config/filter.d/zzz-sshd-obsolete-multiline.conf | 3 +-- fail2ban/tests/files/logs/sshd | 3 +++ 3 files changed, 5 insertions(+), 4 deletions(-) diff --git a/config/filter.d/sshd.conf b/config/filter.d/sshd.conf index 12631cb3..7a7f5e48 100644 --- a/config/filter.d/sshd.conf +++ b/config/filter.d/sshd.conf @@ -73,11 +73,10 @@ mdre-normal-other = ^(Connection closed|Disconnected) ^kex_exchange_identification: client sent invalid protocol identifier ^Bad protocol version identification '.*' from - ^Connection reset by ^SSH: Server;Ltype: (?:Authname|Version|Kex);Remote: -\d+;[A-Z]\w+: ^Read from socket failed: Connection reset by peer # same as mdre-normal-other, but as failure (without ) and [preauth] only: -mdre-ddos-other = ^(Connection closed|Disconnected) (?:by|from)%(__authng_user)s %(__on_port_opt)s\s+\[preauth\]\s*$ +mdre-ddos-other = ^(Connection (?:closed|reset)|Disconnected) (?:by|from)%(__authng_user)s %(__on_port_opt)s\s+\[preauth\]\s*$ mdre-extra = ^Received disconnect from %(__on_port_opt)s:\s*14: No supported authentication methods available ^Unable to negotiate with %(__on_port_opt)s: no matching <__alg_match> found. diff --git a/fail2ban/tests/config/filter.d/zzz-sshd-obsolete-multiline.conf b/fail2ban/tests/config/filter.d/zzz-sshd-obsolete-multiline.conf index d61a6520..4ff4ac68 100644 --- a/fail2ban/tests/config/filter.d/zzz-sshd-obsolete-multiline.conf +++ b/fail2ban/tests/config/filter.d/zzz-sshd-obsolete-multiline.conf @@ -57,8 +57,7 @@ mdre-normal = mdre-ddos = ^%(__prefix_line_sl)sDid not receive identification string from ^%(__prefix_line_sl)sBad protocol version identification '.*' from - ^%(__prefix_line_sl)sConnection closed by%(__authng_user)s %(__on_port_opt)s\s+\[preauth\]\s*$ - ^%(__prefix_line_sl)sConnection reset by + ^%(__prefix_line_sl)sConnection (?:closed|reset) by%(__authng_user)s %(__on_port_opt)s\s+\[preauth\]\s*$ ^%(__prefix_line_ml1)sSSH: Server;Ltype: (?:Authname|Version|Kex);Remote: -\d+;[A-Z]\w+:.*%(__prefix_line_ml2)sRead from socket failed: Connection reset by peer%(__suff)s$ mdre-extra = ^%(__prefix_line_sl)sReceived disconnect from %(__on_port_opt)s:\s*14: No supported authentication methods available diff --git a/fail2ban/tests/files/logs/sshd b/fail2ban/tests/files/logs/sshd index 0385f38c..e45ca90d 100644 --- a/fail2ban/tests/files/logs/sshd +++ b/fail2ban/tests/files/logs/sshd @@ -296,6 +296,9 @@ Nov 24 23:46:43 host sshd[32686]: fatal: Read from socket failed: Connection res # failJSON: { "time": "2005-03-15T09:20:57", "match": true , "host": "192.0.2.39", "desc": "Singleline for connection reset by" } Mar 15 09:20:57 host sshd[28972]: Connection reset by 192.0.2.39 port 14282 [preauth] +# failJSON: { "time": "2005-03-16T09:29:50", "match": true , "host": "192.0.2.20", "desc": "connection reset by user (gh-2662)" } +Mar 16 09:29:50 host sshd[19131]: Connection reset by authenticating user root 192.0.2.20 port 1558 [preauth] + # failJSON: { "time": "2005-07-17T23:03:05", "match": true , "host": "192.0.2.10", "user": "root", "desc": "user name additionally, gh-2185" } Jul 17 23:03:05 srv sshd[1296]: Connection closed by authenticating user root 192.0.2.10 port 46038 [preauth] # failJSON: { "time": "2005-07-17T23:04:00", "match": true , "host": "192.0.2.11", "user": "test 127.0.0.1", "desc": "check inject on username, gh-2185" }