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extend and refact script-side of NTP analyzer

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This commit is contained in:
Palumbo Mauro 2019-06-03 17:50:32 +02:00
parent 411908a102
commit ce07b10aa8
3 changed files with 180 additions and 105 deletions
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3
scripts/base/protocols/ntp/__load__.zeek
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@ -1,3 +1,2 @@
# Generated by binpac_quickstart
@load ./main
@load ./consts
#@load-sigs ./dpd.sig

2
scripts/base/protocols/ntp/dpd.sig
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@ -1,5 +1,3 @@
# Generated by binpac_quickstart
signature dpd_ntp {
ip-proto == udp

236
scripts/base/protocols/ntp/main.zeek
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@ -1,6 +1,10 @@
module NTP;
@load ./consts
# TODO: The recommended method to do dynamic protocol detection
# (DPD) is with the signatures in dpd.sig.
# For the time being, we use port detection.
const ports = { 123/udp };
redef likely_server_ports += { ports };
export {
redef enum Log::ID += { LOG };
@ -12,24 +16,96 @@ export {
uid: string &log;
## The connection's 4-tuple of endpoint addresses/ports.
id: conn_id &log;
## The version of NTP
ver: count &log;
## The stratum (primary, secondary, etc.) of the server
stratum: count &log &optional;
## The precision of the system clock of the client
precision: interval &log &optional;
## The time at the client that the request was sent to the server
org_time: time &log &optional;
## The time at the server when the request was received
rec_time: time &log &optional;
## The time at the server when the reply was sent
xmt_time: time &log &optional;
## The NTP version number (1, 2, 3, 4)
version: count &log;
## The NTP mode being used
mode: count &log;
## The stratum (primary server, secondary server, etc.)
stratum: count &log;
## The maximum interval between successive messages
poll: interval &log;
## The precision of the system clock
precision: interval &log;
## Total round-trip delay to the reference clock
root_delay: interval &log;
## Total dispersion to the reference clock
root_disp: interval &log;
## For stratum 0, 4 character string used for debugging
kiss_code: string &log &optional;
## For stratum 1, ID assigned to the clock by IANA
ref_id: string &log &optional;
## The IP of the server's reference clock
ref_clock: addr &log &optional;
kiss_code: string &optional &log;
## For stratum 1, ID assigned to the reference clock by IANA
ref_id: string &optional &log;
## Above stratum 1, when using IPv4, the IP address of the reference clock
ref_addr: addr &optional &log;
## Above stratum 1, when using IPv6, the first four bytes of the MD5 hash of the
## IPv6 address of the reference clock
ref_v6_hash_prefix: string &optional &log;
## Time when the system clock was last set or correct
ref_time: time &log;
## Time at the client when the request departed for the NTP server
org_time: time &log;
## Time at the server when the request arrived from the NTP client
rec_time: time &log;
## Time at the server when the response departed for the NTP client
xmt_time: time &log;
## Key used to designate a secret MD5 key
key_id: count &optional &log;
## MD5 hash computed over the key followed by the NTP packet header and extension fields
digest: string &optional &log;
## Number of extension fields (which are not currently parsed)
num_exts: count &default=0 &log;
## An integer specifying the command function. Values currently defined includes:
## 1 read status command/response
## 2 read variables command/response
## 3 write variables command/response
## 4 read clock variables command/response
## 5 write clock variables command/response
## 6 set trap address/port command/response
## 7 trap response
## Other values are reserved.
OpCode : count &log;
## The response bit. Set to zero for commands, one for responses.
resp_bit : bool &log;
## The error bit. Set to zero for normal response, one for error response.
err_bit : bool &log;
## The more bit. Set to zero for last fragment, one for all others.
more_bit : bool &log;
## The sequence number of the command or response
sequence : count &log;
## The current status of the system, peer or clock
status : count &log;
## A 16-bit integer identifying a valid association
association_id : count &log;
## An implementation-specific code which specifies the
## operation to be (which has been) performed and/or the
## format and semantics of the data included in the packet.
ReqCode : count &log;
## The authenticated bit. If set, this packet is authenticated.
auth_bit : bool &log;
## For a multipacket response, contains the sequence
## number of this packet. 0 is the first in the sequence,
## 127 (or less) is the last. The More Bit must be set in
## all packets but the last.
sequence : count &log;
## The number of the implementation this request code
## is defined by. An implementation number of zero is used
## for requst codes/data formats which all implementations
## agree on. Implementation number 255 is reserved (for
## extensions, in case we run out).
implementation : count &log;
## Must be 0 for a request. For a response, holds an error
## code relating to the request. If nonzero, the operation
## requested wasn't performed.
##
## 0 - no error
## 1 - incompatible implementation number
## 2 - unimplemented request code
## 3 - format error (wrong data items, data size, packet size etc.)
## 4 - no data available (e.g. request for details on unknown peer)
## 5-6 I don't know
## 7 - authentication failure (i.e. permission denied)
err : count &log;
};
## Event that can be handled to access the NTP record as it is sent on
@ -41,79 +117,81 @@ redef record connection += {
ntp: Info &optional;
};
const ports = { 123/udp };
redef likely_server_ports += { ports };
event zeek_init() &priority=5
{
Log::create_stream(NTP::LOG, [$columns=Info, $ev=log_ntp, $path="ntp"]);
Analyzer::register_for_ports(Analyzer::ANALYZER_NTP, ports);
}
event ntp_message(c: connection, is_orig: bool, msg: NTP::Message) &priority=5
{
# Record initialization
{
local info: Info;
if ( c?$ntp )
info = c$ntp;
else
{
info$ts = network_time();
info$uid = c$uid;
info$id = c$id;
info$ver = msg$version;
info$version = msg$version;
info$mode = msg$mode;
if ( msg$mode < 6 ) {
info$stratum = msg$std_msg$stratum;
info$poll = msg$std_msg$poll;
info$precision = msg$std_msg$precision;
info$root_delay = msg$std_msg$root_delay;
info$root_disp = msg$std_msg$root_disp;
if ( info?$kiss_code)
info$kiss_code = msg$std_msg$kiss_code;
if ( info?$ref_id)
info$ref_id = msg$std_msg$ref_id;
if ( info?$ref_addr)
info$ref_addr = msg$std_msg$ref_addr;
if ( info?$ref_v6_hash_prefix)
info$ref_v6_hash_prefix = msg$std_msg$ref_v6_hash_prefix;
info$ref_time = msg$std_msg$ref_time;
info$org_time = msg$std_msg$org_time;
info$rec_time = msg$std_msg$rec_time;
info$xmt_time = msg$std_msg$xmt_time;
if ( info?$key_id)
info$key_id = msg$std_msg$key_id;
if ( info?$digest)
info$digest = msg$std_msg$digest;
info$num_exts = msg$std_msg$num_exts;
}
# From the request, we get the desired precision
if ( is_orig )
{
info$precision = msg$precision;
if ( msg$mode==6 ) {
info$OpCode = msg$control_msg$OpCode;
info$resp_bit = msg$control_msg$resp_bit;
info$err_bit = msg$control_msg$err_bit;
info$more_bit = msg$control_msg$more_bit;
info$sequence = msg$control_msg$sequence;
info$status = msg$control_msg$status;
info$association_id = msg$control_msg$association_id;
}
if ( msg$mode==7 ) {
info$ReqCode = msg$mode7_msg$ReqCode;
info$auth_bit = msg$mode7_msg$auth_bit;
info$sequence = msg$mode7_msg$sequence;
info$implementation = msg$mode7_msg$implementation;
info$err = msg$mode7_msg$err;
}
# Copy the present packet info into the connection record
# If more ntp packets are sent on the same connection, the newest one
# will overwrite the previous
c$ntp = info;
return;
}
# From the response, we fill out most of the rest of the fields.
info$stratum = msg$stratum;
info$org_time = msg$org_time;
info$rec_time = msg$rec_time;
info$xmt_time = msg$xmt_time;
# Stratum 1 has the textual reference ID
if ( msg$stratum == 1 )
info$ref_id = gsub(msg$ref_id, /\x00*/, "");
# Higher stratums using IPv4 have the address of the reference server.
if ( msg$stratum > 1 )
{
if ( is_v4_addr(c$id$orig_h) )
info$ref_clock = msg$ref_addr;
}
c$ntp = info;
}
# Add the service to the Conn::LOG
add c$service["ntp"];
}
event ntp_message(c: connection, is_orig: bool, msg: NTP::Message) &priority=-5
{
if ( ! is_orig )
{
{
# Log every ntp packet into ntp.log
Log::write(NTP::LOG, c$ntp);
delete c$ntp;
}
}
}
event connection_state_remove(c: connection) &priority=-5
{
if ( c?$ntp )
Log::write(NTP::LOG, c$ntp);
}
event zeek_init() &priority=5
{
Analyzer::register_for_ports(Analyzer::ANALYZER_NTP, ports);
event ntp_mode6_message(c: connection, is_orig: bool, opcode: count)
{
print "Mode 6", opcode;
}
Log::create_stream(NTP::LOG, [$columns = Info, $ev = log_ntp]);
}
event ntp_mode7_message(c: connection, is_orig: bool, opcode: count)
{
print "Mode 7", opcode;
}