You will get these missions if you accept Arunmor's proposal when it is offered to you after ARC ask you to destroy Arunmor's system.

Finish Special Missions, and get little awards.
Backfire 
Mission Description: Send a File
Payment: 15000c
Software Requirements: Revelation
Description: After accepting the offer from ARC, wait for Arunmor to give you a counter-offer. Reply to the mail they send you, with Revelation attached, and they will give you 15000c. After completing this mission, you will be on the Arunmor side of the storyline.
Tracer 
Mission Description: Upload and run a file.
Payment: 10000c
Software Requirements: File Copier, Password Breaker, Monitor Bypass v5, Proxy Bypass v5, Firewall Bypass v5
Description: First, connect to the Arunmor File Server, and copy the RevelationTracer to your memory. Next, connect to ARC Internal Services Machine, and bypass all the Monitor, Proxy and Firewall. Break the password and enter the File Server. Run your file copier on the RevelationTracer, then copy it to the File Server, then go to the Console. Enter the usr directory (type 'cd usr') and the run the RevelationTracer (type 'run revelationtracer') and wait for it to say the program is hiding itself. Once this is done, disconnect, clear your logs and reply to the email.
TakeMeToYourLeader 
Mission Description: Upload and run a file.
Payment: 30000c
Software Requirements: File Copier, Password Breaker, Monitor Bypass v5, Proxy Bypass v5, Firewall Bypass v5
Description: This mission is almost identical to the last one. If you still have the copy of Revelation that ARC sent you, you can proceed with the mission. Otherwise you will need to connect to Arunmor File Server and get a copy before hand. Connect to Arunmor Internal Services Machine and bypass the Monitor, Proxy and Firewall. Break the password and enter the File Server. Run your file copier on Revelation, then copy it to the File Server, then go to the Console. Enter the usr directory (type 'cd usr') and the run Revelation (type 'run revelation') and wait for the Virus to become active. You will automatically be disconnected when it does, and a red square will appear on the world map. Once this is done, disconnect, clear your logs and reply to the email.
ARCInfiltration 
Mission Description: Copy a Database.
Payment: 30000c
Software Requirements: File Copier, Password Breaker, Monitor Bypass v5, Proxy Bypass v5, LAN Scan, LAN Probe, LAN Spoof, Voice Analyser, Decypher, Decrypter v5
Other Requirements: 90Gq Memory Space
Description: Before you connect to ARC Local Area Network, you will need to get the Voice Pattern of the ARC Admin, so go to the ARC Public Access Server to get his number, then connect and record his voice.
Now, go to ARC Local Area Network, and Bypass the Monitor and Proxy. You will now need to work your way through the LAN Since the LAN is randomly generated each time, there is no set way to do this, but you should aim for the Main Server system (Refer to Section 3.1 if you need help getting through LANs). When you are in the system, enter the File Server, and at the bottom should be 9 files, 10Gq each, named ARC-Revelation x.dat. These are the files you need to copy. Copy all the files to your memory, disconnect, and clear your logs. Now, connect to the Arunmor File Server and copy all of the files onto it. If there isn't enough space, delete any useless files that may have appeared. Once you have copied all of the files, use the Decrypter on them, and then you can reply to the mail and finish the mission. If you didn't have enough memory space for all the files, you will need to make 2 trips.
CounterAttack 
Mission Description: Destroy Revelation
Payment: 50000c
Required Software: Faith, Revelation Tracker, IP Lookup, Voice Analyser, Decypher, Monitor Bypass v5, Proxy Bypass v5, Firewall Bypass v5, File Copier.
Description: The final Arunmor mission. There is only one way to do this one, and that is quickly. First of all, go to Arunmor's File Server, and get a copy of Faith and Revelation Tracker. Run Revelation Tracker straight away, as that will give you IP's of infected systems. Use your IP lookup to get the link from each IP, and connect to the system. Break through what ever security the system has, and enter the file server. Copy Faith to the system, then go into the console and run it. A few seconds later, Revelation should be cleared from the system. Disconnect, and continue doing the same thing until the mission is complete. You do not have time to clear your logs on this one, so make sure you have a Motion Sensor and Gateway Nuke, and that the Motion Sensor is running.
HINTS: Don't bother with Banks or Central Mainframes. Leave them and let Revelation spread to a system that you can hack quicker (Internal Services).
Don't waste time. Revelation only needs 2 minutes to be able to spread to 2 other systems. Disinfect a system and then move on to the next one.
After you have finished the mission, keep an eye on your Motion Sensor. Since you didn't have time to cover your logs, you will be traced, so you will need to Nuke your gateway. Its also worth noting that ARC may try and frame you a while after this mission, so you should keep your eye on your motion sensor at all times, or you may well find yourself Disavowed for hacking ARC Central Mainframe when you didn't do it. You will also have a criminal record that needs clearing if this happens.
Alternate Ways of Fighting Revelation
On the forums, several other ways of fighting the virus have been put forward. Though I've not tested these myself, I'm told they work by others. So, here they are.
1. Instead of running faith on a system, go straight to the console, and shut the system down (by deleting the sys directory and then using the shutdown command). Revelation will still show up on the map, but when the 2 minutes pass, since the system is no longer running, the virus cannot spread and the infection will disappear.
2. When the Revelation outbreak occurs, connect to ARC Central mainframe and crash the system. This will stop the virus from spreading to other computers.
You should note that people have said, using this method, that Revelation will start again when the system comes back online.

Revelation in action

Don't let Revelation infect your computer
This is the end of the Arunmor side of the storyline. After you have finished this mission, keep your eye on the news for the ending of the story.