Dionaea

dionaea

  catches bugs

Dionaea is meant to be a nepenthes successor, embedding python as scripting language, using libemu to detect shellcodes, supporting ipv6 and tls

* Development <#development>
* Compiling & Installation <#compiling>
* Running <#running>
* Configuration <#configuration>
* Honors <#honorem>
* Links <#links>
* FAQ <#FAQ>
* Segfault <#segfault>
* Support <#support>
* Blog <http://carnivore.it>

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How it works

dionaea intention is to trap malware exploiting vulnerabilities exposed by services offerd to a network, the ultimate goal is gaining a copy of the malware.

  Security

As Software is likely to have bugs, bugs in software offering network services can be exploitable, and dionaea is software offering network services, it is likely dionaea has exploitable bugs. Of course we try to avoid it, but if nobody would fail when trying hard, we would not need software such as dionaea. So, in order to minimize the impact, dionaea can drop privileges, and chroot. To be able to run certain actions which require privileges, after dionaea dropped them, dionaea creates a child process at startup, and asks the child process to run actions which require elevated privileges. This does not guarantee anything, but it should be harder to get gain root access to the system from an unprivileged user in a chroot environment.

  Network Connectivity

Given the softwares intented use, network io is crucial. All network io is within the main process in a so called non-blocking manner. To understand nonblocking, imagine you have many pipes infront of you, and these pipes can send you something, and you can put something into the pipe. If you want to put something into a pipe, while it is crowded, you'd have to wait, if you want to get something from a pipe, and there is nothing, you'd have to wait too. Doing this pipe game non-blocking means you won't wait for the pipes to be write/readable, you'll get something off the pipes once data arrives, and write once the pipe is not crowded. If you want to write a large chunk to the pipe, and the pipe is crowded after a small piece, you note the rest of the chunk you wanted to write, and wait for the pipe to get ready. DNS resolves are done using libudns, which is a neat non-blocking dns resolving library with support for AAAA records and chained cnames. So much about non-blocking. dionaea uses libev to get notified once it can act on a socket, read or write. dionaea can offer services via tcp/udp and tls for IPv4 and IPv6, and can apply rate limiting and accounting limits per connections to tcp and tls connections - if required.

  Protocols

Network services speak a certain language, this language is called protocol. When we started deploying honeypots, you could trap worms just by opening a single port, and wait for them to connect and send you an url where you could download a copy of the worm. The service getting attacked was the backdoor of the bagle mailworm, and it did not require and interaction. Later on, the exploitations of real services got more complex, and you had to reply something to the worm to fool him. Nowadays worms use API to access services, before sending their payload. To allow easy adjustments to the procotol, dionaea implements the protocols in python. There is a glue between the network layer which is done in the c programming language and the embedded python scripting language, which allows using the non-blocking connections in python. This has some benefits, for example we can use non-blocking tls connections in python, and we even get rate limiting on them (if required), where pythons own io does not offer such things. On the other hand, it is much more comfortable to implement protocols in python than doing the same in c.

    SMB

The main protocol offerd by dionaea is SMB. SMB has a decent history of remote exploitable bugs, and is a very popular target for worms. dionaeas SMB implementation makes use of an python3 adapted version of scapy. As scapys own version of SMB was pretty limited, almost everything but the Field declarations had to be rewritten. The SMB emulation written for dionaea is used by the mwcollectd http://code.mwcollect.org low interaction honeypot too. Besides the known attacks on SMB dionaea supports uploading files to smb shares. Adding new DCE remote procedure calls is a good start to get into dionaea code, you can use:

SELECT COUNT(), dcerpcrequests.dcerpcrequest_uuid, dcerpcservice_name, dcerpcrequest_opnum FROM dcerpcrequests JOIN dcerpcservices ON(dcerpcrequests.dcerpcrequest_uuid == dcerpcservices.dcerpcservice_uuid) LEFT OUTER JOIN dcerpcserviceops ON(dcerpcserviceops.dcerpcserviceop_opnum = dcerpcrequest_opnum AND dcerpcservices.dcerpcservice = dcerpcserviceops.dcerpcservice )
WHERE dcerpcserviceop_name IS NULL GROUP BY
dcerpcrequests.dcerpcrequest_uuid,dcerpcservice_name,dcerpcrequest_opnum ORDER BY COUNT() DESC;

to identify potential usefull targets of unknown dcerpc calls using the data you gathered and stored in your logsql database. Patches are appreciated.

    http

Dionaea supports http on port 80 as well as https, but there is no code making use of the data gathered on these ports. For https, the self-signed ssl certificate is created at startup.

    ftp

Dionaea provives a basic ftp server on port 21, it can create directories and upload and download files. From my own experience there are very little automated attacks on ftp services and I'm yet to see something interesting happening on port 21.

    tftp

Written to test the udp connection code, dionaea provides a tftp server on port 69, which can serve files. Even though there were vulnerabilities in tftp services, I'm yet to see an automated attack on tftp services.

    MSSQL

This module implements the Tabular Data Stream protocol which is used by Microsoft SQL Server. It listens to tcp/1433 and allows clients to login. It can decode queries run on the database, but as there is no database, dionaea can't reply, and there is no further action. Typically we always get the same query:

exec sp_server_info 1 exec sp_server_info 2 exec sp_server_info 500 select 501,NULL,1 where 'a'='A' select 504,c.name,c.description,c.definition from master.dbo.syscharsets c,master.dbo.syscharsets c1,master.dbo.sysconfigures f where f.config=123 and f.value=c1.id and c1.csid=c.id set textsize 2147483647 set arithabort on

Refer to the blog http://carnivore.it/2010/09/11/mssql_attacks_examined for more information. Patches would be appreciated.

    SIP (VoIP)

This is a VoIP module for the honeypot dionaea. The VoIP protocol used is SIP since it is the de facto standard for VoIP today. In contrast to some other VoIP honeypots, this module doesn't connect to an external VoIP registrar/server. It simply waits for incoming SIP messages (e.g. OPTIONS or even INVITE), logs all data as honeypot incidents and/or binary data dumps (RTP traffic), and reacts accordingly, for instance by creating a SIP session including an RTP audio channel. As sophisticated exploits within the SIP payload are not very common yet, the honeypot module doesn't pass any code to dionaea's code emulation engine. This will be implemented if we spot such malicious messages. The main features of the VoIP module are:

* Support for most SIP requests (OPTIONS, INVITE, ACK, CANCEL, BYE)
* Support for multiple SIP sessions and RTP audio streams
* Record all RTP data (optional)
* Set custom SIP username and secret (password)
* Set custom useragent to mimic different phone models
* Uses dionaea's incident system to log to SQL database

Currently the module does not really play nice with scanning software like sipvicious, and could really need some love. If you want to volunteer, just send me patches.

  Exploitation

Attackers do not seek your service, attackers want to exploit you, they'll chat with the service for some packets, and afterwards sent a payload. dionaea has to detect and evaluate the payload to be able to gain a copy of the malware. In order to do so, dionaea uses libemu. Given certain circumstances, libemu can detect shellcode, measure the shellcode, and if required even execute the shellcode. Shellcode detection is done by making use of GetPC heuristics, others wrote papers about it, we decided to write libemu to do so. This detection is rather time consuming, and therefore done using threads. The part of dionaea which takes care of the network io can create a copy of all in/output run for a connection, this copy is passed to the detection facility, which is a tree of detection facilities, at this moment there is only a single leaf, the emu plugin. The emu plugin uses threads and libemu to detect and profile/measure shellcode. Shellcode measurement/profiling is done by running the shellcode in the libemu vm and recording API calls and arguments. For most shellcode profiling is sufficient, the recorded API calls and arguments reveal enough information to get an idea of the attackers intention and act upon them. For multi-stage shellcode, where the first exploitation stage of the shellcode would retrieve a second shellcode from the attacker, profiling is not sufficient, as we lack the information 'what to do' from the second stage of the shellcode, in this case we need to make use of shellcode execution. Shellcode execution is basically the same as shellcode profiling, the only difference is not recording the api calls, and we allow the shellcode to take certain actions, for example creating a network connection.

    Payloads

Once we have the payload, and the profile, dionaea has to guess the intention, and act upon it

      Shells - bind/connectback

This payload offers a shell