ILOVEYOU
Email with an infected attachment
Alias	Love Bug, Loveletter
Type	Computer worm
Origin	Manila, Philippines
Authors	Onel de Guzman
Technical details
Platform	Windows 9x, Windows NT 4.0, Windows 2000
Size	10.31 kilobytes
Written in	VBScript

ILOVEYOU, sometimes referred to as the Love Bug or Loveletter, was a computer worm that infected over ten million Windows personal computers on and after 5 May 2000. It started spreading as an email message with the subject line "ILOVEYOU" and the attachment "LOVE-LETTER-FOR-YOU.TXT.vbs".^[1] At the time, Windows computers often hid the latter file extension ("VBS", a type of interpreted file) by default because it is an extension for a file type that Windows knows, leading unwitting users to think it was a normal text file. Opening the attachment activates the Visual Basic script. First, the worm inflicts damage on the local machine, overwriting random files (including Office files and image files; however, it hides MP3 files instead of deleting them), then, it copies itself to all addresses in the Windows Address Book used by Microsoft Outlook, allowing it to spread much faster than any other previous email worm.^[2][3]

Onel de Guzman,^[4] a then-24-year-old computer science student at AMA Computer College^[5] and resident of Manila, Philippines, created the malware. Because there were no laws in the Philippines against making malware at the time of its creation, the Philippine Congress enacted Republic Act No. 8792, otherwise known as the E-Commerce Law, in July 2000 to discourage future iterations of such activity. However, the Constitution of the Philippines prohibits ex post facto laws, and as such de Guzman could not be prosecuted.^[6]

The ILOVEYOU worm was coded by Onel de Guzman, then a student at AMA Computer College of the Philippines. At the time of its creation, de Guzman was poor and struggling to pay for the country's dial-up internet access.^[5] De Guzman believed that internet access was a human right,^[5] and submitted an undergraduate thesis to the college which proposed the development of a trojan to steal internet login details.^[7] He claimed that this would allow users to be able to afford an internet connection, arguing that those affected by it would experience no loss.^[5] The proposal was rejected by the college, which remarked that his proposal was "illegal" and that "they did not produce burglars".^[7] This led de Guzman to claim that his professors were closed-minded,^[4] and he ultimately dropped out of the college and began development of the worm.^[8]

De Guzman wrote ILOVEYOU in VBScript, and the Windows Script Host is utilized to run the code. ILOVEYOU was distributed through malicious email attachments. The worm was found in emails with the subject "ILOVEYOU" and a message of "Kindly check the attached love letter from me!" The attachment LOVE-LETTER-FOR-YOU.TXT.vbs contained the worm.^[9]

Upon opening the file, the worm copies itself into relevant directories so it will be run upon reboot of the computer. Two of the three copies masquerade as legitimate Microsoft Windows library files, named MSKernel32.vbs and Win32DLL.vbs. The other copy retains the original LOVE-LETTER-FOR-YOU.TXT.vbs name.^[10]

The worm attempts to download a trojan horse named WIN-BUGSFIX.exe. To achieve this, the victim's Internet Explorer homepage is set to a URL that downloads the trojan upon opening the browser. If the download is successful, the trojan is set to run upon reboot and the Internet Explorer homepage is set to a blank page. The trojan fulfils Guzman's primary aim by stealing passwords.^[10]

The worm sends its trademark email to all contacts in the victim's address book. To prevent multiple emails being sent to one person from each successive run of the worm, a registry key is generated for each address book entry once an email has been sent. The worm will only send an email if the registry key is not present. This also allows for emails to be sent to new contacts placed in the address book. ILOVEYOU also has the capability to spread via Internet Relay Chat channels.^[10]

The worm searches connected drives for files to modify. All VBScript files it finds (.vbs, .vbe) are overwritten with the worm's code. Files with extensions .jpg, .jpeg, .js, .jse, .css, .wsh, .sct, .doc and .hta are replaced with copies of the worm that have the same base file name but appended with the .vbs extension. Copies for .mp2 and .mp3 files are similarly produced, but the original files are hidden instead of removed.^[10]

The email format is considered to be one of the first examples of malware using social engineering,^[11] by encouraging victims to open the attached file under the pretext they had a lover who was attempting to contact them.^[12] This was exacerbated by the fact that emails appeared to come from close contacts as a result of the worm's use of its previous victim's contact lists.^[13] The worm's subsequent success has resulted in the use of social engineering in many modern-day malware attacks.^[11] The attachment exploited a feature of Microsoft Outlook where only one file extension would be displayed. As the file name was parsed from left to right, which would be stopped after the first period, to victims the attachment would appear to be an inconspicuous .txt file incapable of holding malware. The worm's real .vbs extension was hidden.^[13] De Guzman also claimed that a bug in Windows 95, where code in email attachments was automatically run upon being clicked, contributed to the worm's success.^[5]

The fact that the worm was written in VBScript allowed users to modify it. A user could easily change the worm to replace essential files and destroy the system, allowing more than 25 variations of ILOVEYOU to spread across the Internet, each doing different kinds of damage.^[14] Most of the variations had to do with what file extensions were affected by the worm. Others modified the email subject to target a specific audience, like the variant "Cartolina" ("postcard") in Italian or "BabyPic" for adults. Some others only changed the credits to the author, which were initially included in the standard version of the virus, removing them entirely or referencing false authors.^[14] Others overwrote "EXE" and "COM" files, and the user's computer would then be unbootable upon restarting.^{[citation needed]}

Some mail messages sent by ILOVEYOU include:

• VIRUS ALERT!!^[15]
• Important! Read Carefully!!^[15]

Originally designing the worm to only work in Manila, De Guzman removed this geographic restriction out of curiosity, which allowed the worm to spread worldwide. De Guzman did not expect this worldwide spread.^[5]

The worm originated in the Pandacan neighborhood of Manila in the Philippines on 4 May 2000,^[16] thereafter moving westward through corporate email systems as employees began their workday that Friday morning – moving first to Hong Kong, then to Europe, and finally the United States.^[17][18] 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.^[19]

The outbreak was estimated to have caused US$5.5–8.7 billion in damages worldwide,^{[20][21][better source needed]} and estimated to cost US$10–15 billion to remove the worm.^[22][23] Within ten days, over fifty million infections had been reported,^[24] and it is estimated that 10% of Internet-connected computers in the world had been affected.^[22] Damage cited was mostly the time and effort spent getting rid of the infection and recovering files from backups. At the time, it was one of the world's most destructive computer related disasters ever.^[25][26][27]

In the United Kingdom, the worm reached the email servers of the House of Commons on 4 May.^[7] The servers were shut down for two hours in response.^[17] The worm affected the banking system of Belgium.^[28]

The worm affected most federal government agencies and caused disruption to multiple, including the Department of Justice, the Department of Labor and the Social Security Administration.^[28] Operations of the Department of Defence were significantly obstructed,^[28] with the Central Intelligence Agency additionally affected^[17] and the United States Army having 2258 infected workstations which cost approximately US$79,200 to recover.^[29] The Veterans Health Administration received 7,000,000 ILOVEYOU emails during the outbreak, requiring 240 man-hours of work to resolve the problems created.^[28] Files at the National Aeronautics and Space Administration were damaged, and in some cases unrecoverable from backups.^[28]

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.^{[citation needed]}

"I love you [rev.eng]" exhibited in July 2006 is a revamped and expanded version of an exhibition shown in June 2002 in the Museum for Applied Art in Frankfurt, in February 2003 at transmediale in Berlin, in August 2004 at the Watson Institute of the Brown University USA and in October 2004 at the Museum for Communication Copenhagen, Denmark.^[30] In 2009, Kiat Kiat Projects curated an email exhibition entitled "How to Prevent Hair Loss" inspired by ILOVEYOU.^[31][32]

The worm inspired the 2011 movie Subject: I Love You starring Jericho Rosales and Briana Evigan.^[33] In 2019, The Persistence of Chaos, a laptop infected with six viruses including ILOVEYOU was sold at auction by Chinese artist Guo O Dong.^[34] In November 2024, The Museum of Malware Art in Helsinki, Finland included a sculpture about ILOVEYOU.^[35]

On 5 May 2000, de Guzman and another young Filipino programmer named Reonel Ramones became targets of a criminal investigation by agents of the Philippines' National Bureau of Investigation (NBI).^[36] 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.^[37]

De Guzman attempted to hide the evidence by removing his computer from his apartment, but he accidentally left some disks behind that contained the worm, as well as information that implicated a possible co-conspirator.^[5]

After surveillance and investigation by Darwin Bawasanta of Sky Internet, the NBI traced a frequently appearing telephone number^{[clarification needed]} to Ramones' apartment in Manila. His residence was searched and Ramones was arrested and placed under investigation by the Department of Justice (DOJ). De Guzman was also charged in absentia.^{[citation needed]}

At that point, the NBI was unsure of what felony or crime would apply.^[36] It was suggested they be charged with violating Republic Act 8484 (the Access Device Regulation Act), a law designed mainly to penalize credit card fraud, since both used pre-paid (if not stolen) Internet cards to purchase access to ISPs. Another idea was that they could 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 might have unwittingly released the worm.^[4] At a press conference organized by his lawyer on 11 May, he said "It is possible" when asked whether he might have done so.^[5]

To show intent, the NBI investigated AMA Computer College, where de Guzman had dropped out at the very end of his final year.^[36]

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.^[38] To address this legislative deficiency,^[36] the Philippine Congress enacted Republic Act No. 8792,^[39] otherwise known as the E-Commerce Law, in July 2000, months after the worm outbreak.^[6]

In 2012, the Smithsonian Institution named ILOVEYOU one of the top ten most virulent computer viruses in history.^[12]

De Guzman did not want public attention. His last known public appearance was at the 2000 press conference, where he obscured his face and allowed his lawyer to answer most questions; his whereabouts remained unknown for 20 years afterward. In May 2020, investigative journalist Geoff White revealed that while researching his cybercrime book Crime Dot Com, he had found de Guzman working at a mobile phone repair stall in Manila. De Guzman admitted to creating and releasing the virus.^[40] He claimed he had initially developed it to steal internet access passwords, since he could not afford to pay for access. He also stated that he created it alone, clearing the two others who had been accused of co-writing the worm.^[41][42]

• Christmas Tree EXEC
• Code Red worm
• Computer virus
• NewLove
• Nimda
• Timeline of notable computer viruses and worms
• The Persistence of Chaos (artwork)

• The Love Bug - A Retrospect
• ILOVEYOU Virus Lessons Learned Report, Army Forces Command (archive)
• Radsoft: The ILOVEYOU Roundup
• "No 'sorry' from Love Bug author" at The Register
• CERT Advisory CA-2000-04 Love Letter Worm (archive)