[IntelMQ-users] IEP03: IntelMQ Data Format - Multiple Values
Sebastian Waldbauer
waldbauer at cert.at
Tue Mar 30 17:53:47 CEST 2021
Dear IntelMQ Developers and Users,
an evaluation of current challenges with the internal data format led to
the idea of allowing multiple values for one field in IntelMQ 3.0
(scheduled for June 2021)[0].
The idea is described below, including various advantages and
disadvantages. We appreciate your input, opinion and analysis of further
implications on this idea.
We plan to evaluate the feedback that emerged in two weeks.
[0]
https://github.com/certtools/intelmq/blob/version-3.0-ideas/docs/architecture-3.0.md#user-content-general-requirements
"The new IDF shall support (sorted) lists of IPs, domains,
taxonomy categories, etc. By convention the most relevant item in such a
list MUST be the first item in the sorted list."
https://github.com/certtools/intelmq/blob/version-3.0-ideas/docs/architecture-3.0.md#user-content-interoperability-with-certpls-[0]:
n6-system
"Since the new IDF shall support multiple values, mapping to n6
should be rather easy."
## Use-cases
### Network information
IntelMQ's format currently allows for *exactly one* value per field. For
example, every event can have *one* `source.ip` and *one* `source.fqdn`.
In some use-cases, multiple values can be useful, for example when
querying DNS information. One domain (`source.fqdn`) can point to
multiple IP addresses (`source.ip`). The other way round, multiple
domains point to the same IP address is also very common. The use-case
first appeared was that one IP address can be part of multiple
Autonomous systems (`source.asn`).[1][2][3]
See the examples below in section Format.
[1]: "Multiple ASNs/networks per IP? #543"
https://github.com/certtools/intelmq/issues/543
[2]: "BOT: DNS lookup #373" https://github.com/certtools/intelmq/issues/373
[3]: "reverse DNS: Only first record is used
"https://github.com/certtools/intelmq/issues/877
### Classification
Another use-case is to use multiple classifications.[5] For example, if
a website was hacked and used for a phishing page, it can be assigned
two classifications:
For the hacking: Taxonomy: information-content-security, type:
unauthorised-modification-of-information
For the phishing page: Taxonomy: fraud, type: phishing
Another example are reachable networks services, which should not be
accessible by the internet. Shadowserver provides a lot of this data.
Open XDMCP instances are both DDoS amplifiers and Potentially unwanted
accessible systems. Therefore both classifications apply:
Taxonomy: vulnerable, type: ddos-amplifier
Taxonomy: vulnerable, type: potentially-unwanted-accessible-system
A list of all fields on the RSIT can be found in the RSIT repository[6]
[5]:
https://github.com/enisaeu/Reference-Security-Incident-Taxonomy-Task-Force/blob/master/Documentation/Usage.md#user-content-multiple-classifications
[6]:
https://github.com/enisaeu/Reference-Security-Incident-Taxonomy-Task-Force/blob/master/working_copy/humanv1.md
## Format
Some examples:
{"source.ip": ["192.0.43.8"], "source.asn": [16876, 40528]}
{"source.ip": ["10.0.0.1", "10.0.0.2"], "source.url":
["http://example.com/", "http://example.net"]}
{"classification.taxonomy": ["information-content-security", "fraud"],
"classification.type": ["unauthorised-modification-of-information",
"phishing"], "source.url": ["http://example.com/"], "source.ip":
["10.0.0.1", "10.0.0.2"]}
In the bots' code multiple values need to be taken car of. For example,
instead of:
ip_addr = event["source.ip"]
# do stuff
it is necessary to loop over the values:
for ip_addr in event["source.ip"]:
# do stuff
This logic is required for *all* fields which can have multiple values,
therefore nested loops may be necessary.
Everything which processes IntelMQ data needs to be adapted, including
data bases. See the "Disadvantages" section below.
### Optional back-conversion ("value-explosion")
One variant/option of this IEP is to create a conversion layer from the
new multi-value format to the old one-value format by creating multiple
events with only one value per field. Using this conversion,
compatibility with external components can be kept, while the advantages
only exist inside the IntelMQ core (ie. the bots).
Examples:
{"source.ip": ["127.0.0.1", "127.0.0.2"], "source.fqdn": ["example.com"]}
-> {"source.ip": "127.0.0.1", "source.fqdn": ["example.com"]},
{"source.ip": "127.0.0.2", "source.fqdn": ["example.com"]}
{"source.ip": ["127.0.0.1", "127.0.0.2"], "source.fqdn": ["example.com",
"example.org"]}
-> {"source.ip": "127.0.0.1", "source.fqdn": "example.com"},
{"source.ip": "127.0.0.1", "source.fqdn": "example.org"}, {"source.ip":
"127.0.0.2", "source.fqdn": "example.com"}, {"source.ip": "127.0.0.2",
"source.fqdn": "example.org"}
### What will change?
We'll change the behaviour of the current IntelMQ internal parsing
process, i. e. you'll be able to add multiple IP addresses to on field,
which will be handled as multiple events, but merged into one event.
This will allow us to combine i. e. a domain with multiple IP addresses
to one event.
### Advantages
Supporting multiple values allows us to add multiple IP addresses to one
event. As opposed to using multiple events with nearly similar data, the
multiple-value approach reduces data duplication and has less overhead,
while on the other hand the complexity increases.
If multiple events would be used instead, related events would need to
be linked together by other means (see section Alternative below).
### Disadvantages (breaking behaviour)
The complexity in IntelMQ and all linked components increases without
doubt. All components dealing with the IntelMQ-data need to be adapted
to deal with multiple values. This includes all bots, but IntelMQ
administrators need to adapt their configurations (e.g. filters, etc.)
as well.
Without the explosion-variant, all connected databases need to be
adapted (e.g. PostgreSQL, SQLite, Elastic, MongoDB etc.) additionally
and all software which is processing data from IntelMQ need to be
adapted. PostgreSQL support arrays for columns, but the scheme
conversion can be complex and resource-hungry.
IntelMQ followed the KISS ("keep it simple, stupid")[4] principle from
its beginning. It is disputable if multiple values breaks with this
principle.
[4]: https://en.wikipedia.org/wiki/KISS_principle
## Alternatives
An alternative to using multiple values per field is to set unique
identifiers (e.g. UUID) per event and let events with the same origin
have the same "parent" identifier. This way, related events can be
linked and compatibility is easier. Relating the events to each other
requires extra steps although, but keeps the KISS principle. This
approach will be described in IEP04.
To solve the use-case of multiple classifications per event, the primary
and most important classification can be used instead of multiple ones.
A possible solution for the classification use-case above would be to
some sort of tagging - in short "tags". I. e.
{
"source.ip": ["192.0.43.8"],
"source.asn": [16876, 40528],
"tags": ["ddos-amplifier", "info-disclosure", "mirai-botnet"]
}
## Other IoC processing formats
For reference, we describe the formats of other IoC-processing systems
similar to IntelMQ. Both formats, IDEA and n6 do support multiple values
in different kinds. If you know of other similar formats supporting
multiple values, please speak up!
### "IDEA"
The IDEA-format, used by CESNET-developed Warden, supports multiple
values for some fields. But the data format structure differs clearly
from IntelMQ's, as you can see in the example below. The classification
is defined per address and network ranges are possible as addresses,
what is not supported in IntelMQ.
IDEA was designed from scratch to overcome disadvantages of Warden's
previous data format.
Example:
"Source": [
{
"Type": ["Phishing"],
"IP4": ["192.168.0.2-192.168.0.5", "192.168.0.10/25"],
"IP6": ["2001:0db8:0000:0000:0000:ff00:0042::/112"],
"Hostname": ["example.com"],
"URL": ["http://example.com/cgi-bin/killemall"],
"Proto": ["tcp", "http"],
"AttachHand": ["att1"],
"Netname": ["ripe:IANA-CBLK-RESERVED1"]
}
],
"Target": [
{
"Type": ["Backscatter",
"OriginSpam"],
"Email": ["innocent at example.com"],
"Spoofed": true
},
{
"IP4": ["10.2.2.0/24"],
"Anonymised": true
}
]
Upstream documentation:
https://idea.cesnet.cz/en/index
https://warden.cesnet.cz/en/index
### n6
In the n6 format, the addr field is a list of arrays with `ip`, `asn`,
`cc` and `dir` fields. `addr` is similar to IntelMQ's `source`
namespace, but the size of `addr` is much lower and the "direction" of
the address is given by a field inside the addr item.
Example:
[{"ipv6": "abcd::1", "cc": "PL", "asn": 12345, "dir": "dst"}]
Upstream documentation:
https://n6sdk.readthedocs.io/en/latest/tutorial.html#field-class-addressfield
https://n6sdk.readthedocs.io/en/latest/tutorial.html#field-class-extendedaddressfield
--
// Sebastian Waldbauer <waldbauer at cert.at> - T: +43 1 5056416 7202
// CERT Austria - https://www.cert.at/
// Eine Initiative der nic.at GmbH - https://www.nic.at/
// Firmenbuchnummer 172568b, LG Salzburg
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