Provided by: certspotter_0.18.0-1_amd64 
NAME
certspotter-script - Certificate Transparency Log Monitor (hook script)
DESCRIPTION
certspotter-script is any program that is executed by certspotter(8) when it needs to notify you about an
event, such as detecting a certificate for a domain on your watch list.
Scripts are placed in the $CERTSPOTTER_CONFIG_DIR/hooks.d directory (~/.certspotter/hooks.d by default),
or specified on the command line using the -script argument.
ENVIRONMENT
Event information
The following environment variables are set for all types of events:
EVENT
One of the following values, indicating the type of event:
• discovered_cert - certspotter has discovered a certificate for a domain on your watch list.
• malformed_cert - certspotter can’t determine if a certificate matches your watch list because the
certificate or the log entry is malformed.
• error - a problem is preventing certspotter from monitoring all logs.
Additional event types may be defined in the future, so your script should be able to handle unknown
values.
SUMMARY
A short human-readable string describing the event. This is the same string used in the subject line
of emails sent by certspotter.
Discovered certificate information
The following environment variables are set for discovered_cert events:
WATCH_ITEM
The item from your watch list which matches this certificate. (If more than one item matches, the
first one is used.)
LOG_URI
The URI of the log containing the certificate.
ENTRY_INDEX
The index of the log entry containing the certificate.
TBS_SHA256
The hex-encoded SHA-256 digest of the TBSCertificate, as defined in RFC 6962 Section 3.2.
Certificates and their corresponding precertificates have the same TBS_SHA256 value.
CERT_SHA256
The hex-encoded SHA-256 digest (sometimes called fingerprint) of the certificate. The digest is
computed over the ASN.1 DER encoding.
PUBKEY_SHA256
The hex-encoded SHA-256 digest of the certificate’s Subject Public Key Info.
CERT_FILENAME
Path to a file containing the PEM-encoded certificate chain. Not set if -no_save was used.
JSON_FILENAME
Path to a JSON file containing additional information about the certificate. See below for the format
of the JSON file. Not set if -no_save was used.
TEXT_FILENAME
Path to a text file containing information about the certificate. This file contains the same text
that certspotter uses in emails. You should not attempt to parse this file because its format may
change in the future. Not set if -no_save was used.
NOT_BEFORE, NOT_BEFORE_UNIXTIME, NOT_BEFORE_RFC3339
The not before time of the certificate, in a human-readable format, seconds since the UNIX epoch, and
RFC3339, respectively. These variables may be unset if there was a parse error, in which case
VALIDITY_PARSE_ERROR is set.
NOT_AFTER, NOT_AFTER_UNIXTIME, NOT_AFTER_RFC3339
The not after (expiration) time of the certificate, in a human-readable format, seconds since the UNIX
epoch, and RFC3339, respectively. These variables may be unset if there was a parse error, in which
case VALIDITY_PARSE_ERROR is set.
VALIDITY_PARSE_ERROR
Error parsing not before and not after, if any. If this variable is set, then the NOT_BEFORE and
NOT_AFTER family of variables are unset.
SUBJECT_DN
The distinguished name of the certificate’s subject. This variable may be unset if there was a parse
error, in which case SUBJECT_PARSE_ERROR is set.
SUBJECT_PARSE_ERROR
Error parsing the subject, if any. If this variable is set, then SUBJECT_DN is unset.
ISSUER_DN
The distinguished name of the certificate’s issuer. This variable may be unset if there was a parse
error, in which case ISSUER_PARSE_ERROR is set.
ISSUER_PARSE_ERROR
Error parsing the issuer, if any. If this variable is set, then ISSUER_DN is unset.
SERIAL
The hex-encoded serial number of the certificate. Prefixed with a minus (-) sign if negative. This
variable may be unset if there was a parse error, in which case SERIAL_PARSE_ERROR is set.
SERIAL_PARSE_ERROR
Error parsing the serial number, if any. If this variable is set, then SERIAL is unset.
Malformed certificate information
The following environment variables are set for malformed_cert events:
LOG_URI
The URI of the log containing the malformed certificate.
ENTRY_INDEX
The index of the log entry containing the malformed certificate.
LEAF_HASH
The base64-encoded Merkle hash of the leaf containing the malformed certificate.
PARSE_ERROR
A human-readable string describing why the certificate is malformed.
ENTRY_FILENAME
Path to a file containing the JSON log entry. The file contains a JSON object with two fields,
leaf_input and extra_data, as described in RFC 6962 Section 4.6.
TEXT_FILENAME
Path to a text file containing a description of the malformed certificate. This file contains the
same text that certspotter uses in emails.
Error information
The following environment variables are set for error events:
TEXT_FILENAME
Path to a text file containing a description of the error. This file contains the same text that
certspotter uses in emails.
JSON FILE FORMAT
Unless -no_save is used, certspotter saves a JSON file for every discovered certificate under
$CERTSPOTTER_STATE_DIR, and puts the path to the file in $JSON_FILENAME. Your script can read the JSON
file, such as with the jq(1) command, to get additional information about the certificate which isn’t
appropriate for environment variables.
The JSON file contains an object with the following fields:
tbs_sha256
A string containing the hex-encoded SHA-256 digest of the TBSCertificate, as defined in RFC 6962
Section 3.2. Certificates and their corresponding precertificates have the same tbs_sha256 value.
pubkey_sha256
A string containing the hex-encoded SHA-256 digest of the certificate’s Subject Public Key Info.
dns_names
An array of strings containing the DNS names for which the certificate is valid, taken from both the
DNS subject alternative names (SANs) and the subject common name (CN). Internationalized domain names
are encoded in Punycode.
ip_addresses
An array of strings containing the IP addresses for which the certificate is valid, taken from both
the IP subject alternative names (SANs) and the subject common name (CN).
not_before
A string containing the not before time of the certificate in RFC3339 format. Null if there was an
error parsing the certificate’s validity.
not_after
A string containing the not after (expiration) time of the certificate in RFC3339 format. Null if
there was an error parsing the certificate’s validity.
Additional fields will be added in the future based on user feedback. Please open an issue at
https://github.com/SSLMate/certspotter if you have a use case for another field.
EXAMPLES
Example environment variables for a discovered_cert event:
CERT_FILENAME=/home/andrew/.certspotter/certs/3c/3cdc83b3932c194fcdf17aa2bf1abc34e8438b293c3d5c70693e175b38ff128a.pem
CERT_SHA256=3cdc83b3932c194fcdf17aa2bf1abc34e8438b293c3d5c70693e175b38ff128a
ENTRY_INDEX=6464843
EVENT=discovered_cert
ISSUER_DN=C=GB, ST=Greater Manchester, L=Salford, O=Sectigo Limited, CN=Sectigo RSA Domain Validation Secure Server CA
JSON_FILENAME=/usr2/andrew/.certspotter/certs/3c/3cdc83b3932c194fcdf17aa2bf1abc34e8438b293c3d5c70693e175b38ff128a.v1.json
LOG_URI=https://ct.cloudflare.com/logs/nimbus2024/
NOT_AFTER='2024-01-26 03:47:26 +0000 UTC'
NOT_AFTER_RFC3339=2024-01-26T03:47:26Z
NOT_AFTER_UNIXTIME=1706240846
NOT_BEFORE='2023-01-31 03:47:26 +0000 UTC'
NOT_BEFORE_RFC3339=2023-01-31T03:47:26Z
NOT_BEFORE_UNIXTIME=1675136846
PUBKEY_SHA256=33ac1d9b9e56005ccac045eac2398b3e9dd6b3f5b66ae6260f2d478c7c0d82c8
SERIAL=c170fbf3bf27481e5c351a4db6f2dc5f
SUBJECT_DN=CN=sslmate.com
SUMMARY='certificate discovered for .sslmate.com'
TBS_SHA256=2388ee81c6f45cffc73e68a35fa8921e839e20acc9a98e8e6dcaea07cbfbdef8
TEXT_FILENAME=/usr2/andrew/.certspotter/certs/3c/3cdc83b3932c194fcdf17aa2bf1abc34e8438b293c3d5c70693e175b38ff128a.txt
WATCH_ITEM=.sslmate.com
Example JSON file for a discovered certificate:
{
"dns_names": [
"sslmate.com",
"www.sslmate.com"
],
"ip_addresses": [],
"not_after": "2024-01-26T03:47:26Z",
"not_before": "2023-01-31T03:47:26Z",
"pubkey_sha256": "33ac1d9b9e56005ccac045eac2398b3e9dd6b3f5b66ae6260f2d478c7c0d82c8",
"tbs_sha256": "2388ee81c6f45cffc73e68a35fa8921e839e20acc9a98e8e6dcaea07cbfbdef8"
}
SEE ALSO
certspotter(8)
COPYRIGHT
Copyright © 2016-2023 Opsmate, Inc.
BUGS
Report bugs to https://github.com/SSLMate/certspotter.
2023-11-17 certspotter-script(8)