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splunk-malware-filter
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splunk-malware-filter/README.md

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# malware-filter Add-on (Splunk)
- [Installation](#installation)
- [Usage](#usage)
- [geturlhausfilter](#geturlhausfilter)
- [getphishingfilter](#getphishingfilter)
- [getpupfilter](#getpupfilter)
- [getvnbadsitefilter](#getvnbadsitefilter)
- [getbotnetfilter](#getbotnetfilter)
- [getbotnetip](#getbotnetip)
- [getopendbl](#getopendbl)
- [Disable individual commands](#disable-individual-commands)
- [Build](#build)
- [Download failover](#download-failover)
Provide custom search commands to update [malware-filter](https://gitlab.com/malware-filter) lookups. Each command downloads from a source CSV and emit rows as events which can then be piped to a lookup file or used as a subsearch. Each command is exported globally and can be used in any app. This add-on currently does not have any UI.
[Lookup files](./lookups/) can be updated using the bundled scheduled reports every 12 hours, every 15 minutes for botnet_ip.csv and opendbl_ip.csv. The scheduled reports are disabled by default. Enable the relevant schedule that corresponds to the required lookup file. Modify the search string to add [optional arguments](#usage).
Source CSVs will be downloaded via a proxy if configured in "$SPLUNK_HOME/etc/system/local/[server.conf](https://docs.splunk.com/Documentation/Splunk/latest/Admin/Serverconf#Splunkd_http_proxy_configuration)".
Refer to [this article](https://mdleom.com/blog/2023/04/16/splunk-lookup-malware-filter/) for a more comprehensive guide on detecting malicious domain, URL, IP and CIDR range.
Tested on Splunk 9.x.
## Installation
Releases are available at [Splunkbase](https://splunkbase.splunk.com/app/6970) and [GitLab](https://gitlab.com/malware-filter/splunk-malware-filter/-/releases)
Instruction to build the main branch is available at the [Build](#build) section.
## Usage
```
| geturlhausfilter wildcard_prefix=<string> wildcard_suffix=<string> wildcard_affix=<string> message=<string>
| outputlookup override_if_empty=false urlhaus-filter-splunk-online.csv
```
Optional arguments:
- **wildcard_prefix** `<string>`: list of column names to have wildcard "\*" prefixed to their _non-empty_ value. New column(s) named "{column_name}\_wildcard_prefix" will be created. Non-existant column will be silently ignored. Accepted values: `"column_name"`, `"columnA,columnB"`.
- **wildcard_suffix** `<string>`: Same as wildcard_prefix but have the wildcard suffixed instead.
- **wildcard_affix** `<string>`: Same as wildcard_prefix but have the wildcard prefixed and suffixed.
- **message** `<string>`: Add custom message column. New column "custom_message" will be created.
Example:
```
| geturlhausfilter
| outputlookup override_if_empty=false urlhaus-filter-splunk-online.csv
```
| host | path | message | updated |
| ------------ | ---------- | ----------------------------------------- | -------------------- |
| example2.com | /some-path | urlhaus-filter malicious website detected | 2022-12-21T12:34:56Z |
```
| geturlhausfilter wildcard_prefix=path message="lorem ipsum"
| outputlookup override_if_empty=false urlhaus-filter-splunk-online.csv
```
| host | path | message | updated | path_wildcard_prefix | message |
| ------------ | ---------- | ----------------------------------------- | -------------------- | -------------------- | ----------- |
| example2.com | /some-path | urlhaus-filter malicious website detected | 2022-12-21T12:34:56Z | \*/some-path | lorem ipsum |
| example.com | | urlhaus-filter malicious website detected | 2022-12-21T12:34:56Z | | lorem ipsum |
## Lookup files
Lookup files are bundled but they are empty, run the relevant `| getsomething | outputlookup some-filter.csv` to get the latest lookup before using any of them.
- urlhaus-filter-splunk-online.csv
- phishing-filter-splunk.csv
- pup-filter-splunk.csv
- vn-badsite-filter-splunk.csv
- botnet-filter-splunk.csv
- botnet_ip.csv
- opendbl_ip.csv
## geturlhausfilter
```
| geturlhausfilter wildcard_prefix=<string> wildcard_suffix=<string> wildcard_affix=<string> message=<string>
| outputlookup override_if_empty=false urlhaus-filter-splunk-online.csv
```
Output columns are listed here https://gitlab.com/malware-filter/urlhaus-filter#splunk
## getphishingfilter
```
| getphishingfilter wildcard_prefix=<string> wildcard_suffix=<string> wildcard_affix=<string> message=<string>
| outputlookup override_if_empty=false phishing-filter-splunk.csv
```
Output columns are listed here https://gitlab.com/malware-filter/phishing-filter#splunk
## getpupfilter
```
| getpupfilter wildcard_prefix=<string> wildcard_suffix=<string> wildcard_affix=<string> message=<string>
| outputlookup override_if_empty=false pup-filter-splunk.csv
```
Output columns are listed here https://gitlab.com/malware-filter/pup-filter#splunk
## getvnbadsitefilter
```
| getvnbadsitefilter wildcard_prefix=<string> wildcard_suffix=<string> wildcard_affix=<string> message=<string>
| outputlookup override_if_empty=false vn-badsite-filter-splunk.csv
```
Output columns are listed here https://gitlab.com/malware-filter/vn-badsite-filter#splunk
## getbotnetfilter
Highly recommend to use [`getbotnetip`](#getbotnetip) instead.
```
| getbotnetfilter message=<string>
| outputlookup override_if_empty=false botnet-filter-splunk.csv
```
Output columns are listed here https://gitlab.com/malware-filter/botnet-filter#splunk
## getbotnetip
Recommend to update the lookup file "botnet_ip.csv" every 5 minutes (cron `*/5 * * * *`).
```
| getbotnetip message=<string>
| outputlookup override_if_empty=false botnet_ip.csv
```
Columns:
| first_seen_utc | dst_ip | dst_port | c2_status | last_online | malware | updated |
| ------------------- | ------------- | -------- | --------- | ----------- | ------- | -------------------- |
| 2021-01-17 07:44:46 | 51.178.161.32 | 4643 | online | 2023-01-26 | Dridex | 2023-01-25T17:41:16Z |
Source: https://feodotracker.abuse.ch/downloads/ipblocklist.csv
## getopendbl
Recommend to update the lookup file "opendbl_ip.csv" every 15 minutes (cron `*/15 * * * *`).
```
| getopendbl message=<string>
| outputlookup override_if_empty=false opendbl_ip.csv
```
| start | end | netmask | cidr_range | name | updated |
| --------------- | --------------- | ------- | ------------------ | ----------------------------------------- | -------------------- |
| 187.190.252.167 | 187.190.252.167 | 32 | 187.190.252.167/32 | Emerging Threats: Known Compromised Hosts | 2023-01-30T08:03:00Z |
| 89.248.163.0 | 89.248.163.255 | 24 | 89.248.163.0/24 | Dshield | 2023-01-30T08:01:00Z |
Source: https://opendbl.net/
## Example usage
```
| tstats summariesonly=true allow_old_summaries=true count FROM datamodel=Web WHERE Web.action="allowed"
BY Web.user, Web.src, Web.dest, Web.site, Web.url, Web.category, Web.action, index, _time span=1s
| rename Web.* AS *
| lookup urlhaus-filter-splunk-online host AS site, host AS dest OUTPUT message AS description, updated
| lookup urlhaus-filter-splunk-online path_wildcard_prefix AS vendor_url, host AS site, host AS dest OUTPUT message AS description2, updated AS updated2
| lookup phishing-filter-splunk host AS site, host AS dest OUTPUT message AS description3, updated AS updated3
| lookup phishing-filter-splunk path_wildcard_prefix AS vendor_url, host AS site, host AS dest OUTPUT message AS description4, updated AS updated4
| lookup pup-filter-splunk host AS site, host AS dest OUTPUT message AS description5, updated AS updated5
| lookup vn-badsite-filter-splunk host AS site, host AS dest OUTPUT message AS description6, updated AS updated6
| lookup botnet_ip dst_ip AS dest OUTPUT malware AS description7, updated AS updated7
| eval Description=coalesce(description, description2, description3, description4, description5, description6, description7)
| search Description=*
| eval updated=coalesce(updated, updated2, updated3, updated4, updated5, updated6, updated7), "Signature Last Updated"=strftime(strptime(updated." +0000","%Y-%m-%dT%H:%M:%SZ %z"),"%Y-%m-%d %H:%M:%S %z"), Time=strftime(_time, "%Y-%m-%d %H:%M:%S %z"), "Source IP"=src, Username=user, Domain=site, "Destination IP"=dest, URL=url, Action=action
| table Time, index, "Signature Last Updated", "Source IP", Username, Domain, "Destination IP", Description, Action, URL
```
It is not recommended to use subsearch (e.g. `[| inputlookup urlhaus-filter-splunk-online.csv | fields host ]`) for these [lookup tables](./lookups/) especially [urlhaus-filter](./lookups/urlhaus-filter-splunk-online.csv) and [phishing-filter](./lookups/phishing-filter-splunk.csv) because they usually have more than 30,000 rows, which exceed the soft-limit of [10,000 rows](https://docs.splunk.com/Documentation/SplunkCloud/latest/Search/Aboutsubsearches#Subsearch_performance_considerations) returned by subsearch.
## Disable individual commands
Settings -> All configurations -> filter by "malware_filter" app
## Build
```
git clone https://gitlab.com/malware-filter/splunk-malware-filter
cd splunk-malware-filter
python build.py
```
## Download failover
For `get*filter` search commands, the script will attempt to download from the following domains **in sequence** (check out the `DOWNLOAD_URLS` constant in each script):
- malware-filter.gitlab.io
- curbengh.github.io
- curbengh.github.io
- malware-filter.gitlab.io
- malware-filter.pages.dev
- \*-filter.pages.dev
It is not necessary to allow outbound connection to all the above domains, it just depends how much redundancy you prefer.
## Disclaimer
`getbotnetip.py` and `getopendbl.py` are included simply for convenience, their upstream sources are not affiliated with malware-filter.
## Repository Mirrors
https://gitlab.com/curben/blog#repository-mirrors
## License
[Creative Commons Zero v1.0 Universal](LICENSE-CC0.md) and [MIT License](LICENSE)
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