|Common name||Love Letter|
|Point of origin||Philippines|
|Operating system(s) affected||Windows 95, Windows 98, Windows NT, Windows 2000, Windows ME|
ILOVEYOU, sometimes referred to as Love Bug or Love Letter, was a computer worm that attacked tens of millions of Windows personal computers on and after 5 May 2000 local time in the Philippines when it started spreading as an email message with the subject line "ILOVEYOU" and the attachment "LOVE-LETTER-FOR-YOU.txt.vbs". The latter file extension ('vbs', a type of interpreted file) was most often hidden by default on Windows computers of the time (as it is an extensions for a file type that is known by Windows), leading unwitting users to think it was a normal text file. Opening the attachment activated the Visual Basic script. The worm did damage on the local machine, overwriting random types of files (including Office files, image files, and audio files; however after overwriting MP3 files the virus would hide the file), and sent a copy of itself to all addresses in the Windows Address Book used by Microsoft Outlook. In contrast, the Melissa virus only sent copies to the first 500 contacts. This made it spread much faster than any other previous email worm.
Key to success
On the machine system level, ILOVEYOU relied on the scripting engine system setting (which runs scripting language files such as .vbs files) being enabled, and took advantage of a feature in Windows that hid file extensions by default, which malware authors would use as an exploit. Windows would parse file names from right to left, stopping at the first period character, showing only those elements to the left of this. The attachment, which had two periods, could thus display the inner fake "txt" file extension. Text files are considered to be innocuous, as they are normally incapable of running executable code. The worm also used social engineering to entice users to open the attachment (out of actual desire to connect or simple curiosity) to ensure continued propagation. Systemic weaknesses in the design of Microsoft Outlook and Microsoft Windows were exploited that allowed malicious code capable of complete access to the operating system, secondary storage, and system and user data simply by unwitting users clicking on an icon.
Messages generated in the Philippines began to spread westwards through corporate email systems. Because the worm used mailing lists as its source of targets, the messages often appeared to come from acquaintances and were therefore often regarded as "safe" by their victims, providing further incentive to open them. Only a few users at each site had to access the attachment to generate millions more messages that crippled mail systems and overwrote millions of files on computers in each successive network.
The malware originated in the Pandacan neighborhood of Manila in the Philippines on May 5, 2000, thereafter following daybreak westward across the world, moving first to Hong Kong, then to Europe, and finally the United States, as employees began their workday that Friday morning.  The outbreak was later estimated to have caused US$5.5–8.7 billion in damages worldwide, and estimated to cost US$15 billion to remove the worm. Within ten days, over fifty million infections had been reported, and it is estimated that 10% of internet-connected computers in the world had been affected. Damage cited was mostly the time and effort spent getting rid of the infection and recovering files from backups. To protect themselves, The Pentagon, CIA, the British Parliament and most large corporations decided to completely shut down their mail systems. The ILOVEYOU virus infected computers all over the world. At the time it was one of the world's most destructive computer related disasters ever.
The events inspired the song E-mail on the Pet Shop Boys' UK top-ten album of 2002, Release, the lyrics of which play thematically on the human desires which enabled the mass destruction of this computer infection.
The ILOVEYOU Script (the attachment) was written in Microsoft Visual Basic Scripting (VBS) which runs in Microsoft Outlook and was enabled by default. The script added Windows Registry data for automatic startup on system boot.
The worm then searched connected drives and replaced files with extensions JPG, JPEG, VBS, VBE, JS, JSE, CSS, WSH, SCT, DOC, HTA, MP2, and MP3 with copies of itself, while appending the additional file extension VBS, making the user's computer unbootable. However, MP3s and other sound related files were hidden rather than overwritten.
The worm propagated itself by sending out one copy of the payload to each entry in the Microsoft Outlook address book (Windows Address Book). It also downloaded the Barok trojan renamed for the occasion as "WIN-BUGSFIX.EXE".
The fact that the virus was written in VBS provided users a way to modify the virus. A user could easily modify the virus to replace important files in the system, and destroy it. This allowed many variations of ILOVEYOU to spread across the internet, each one doing different kinds of damage.
Some mail messages sent by ILOVEYOU:
On 5 May 2000, two young Filipino computer programmers named Reonel Ramones and Onel de Guzman became targets of a criminal investigation by agents of the Philippines' National Bureau of Investigation (NBI). Local Internet service provider Sky Internet had reported receiving numerous contacts from European computer users alleging that malware (in the form of the "ILOVEYOU" worm) had been sent via the ISP's servers.
After surveillance and investigation by Darwin Bawasanta of Sky Internet, the NBI traced a frequently appearing telephone number to Ramones' apartment in Manila. His residence was searched and Ramones was arrested and placed on inquest investigation before the Department of Justice (DOJ). Onel de Guzman was likewise charged in absentia.
At that point, the NBI were unsure what felony or crime would apply. It was suggested they be charged with violating Republic Act 8484 (the Access Device Regulation Act), a law designed mainly to penalise credit card fraud, since both used pre-paid (if not stolen) Internet cards to purchase access to ISPs. Another idea was that they be charged with malicious mischief, a felony (under the Philippines Revised Penal Code of 1932) involving damage to property. The drawback here was that one of its elements, aside from damage to property, was intent to damage, and de Guzman had claimed during custodial investigations that he may have unwittingly released the worm.
To show intent, the NBI investigated AMA Computer College, where de Guzman had dropped out at the very end of his final year. They found that, for his undergraduate thesis, de Guzman had proposed the implementation of a trojan to steal Internet login passwords. This way, he proposed, users would finally be able to afford an Internet connection. The proposal was rejected by the College of Computer Studies board, prompting de Guzman to cancel his studies the day before graduation.
Since there were no laws in the Philippines against writing malware at the time, both Ramones and de Guzman were released with all charges dropped by state prosecutors. To address this legislative deficiency, the Philippine Congress enacted Republic Act No. 8792, otherwise known as the E-Commerce Law, in July 2000, just two months after the worm outbreak. In 2002, the ILOVEYOU virus obtained a world record for being the most virulent computer virus at the time.
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