2013
- January 2: Anonymous released an incriminating video, photographs, tweets, and hacked emails related to the Steubenville High School football team during the investigation of the Steubenville High School rape case.
- January 13: Anonymous Mexico penetrated the website of the Mexico army, SEDENA, disclosed information including usernames and passwords, and replaced the site content with a video referencing riots during Peña Nieto's presidential inauguration and the Zapatista Army of National Liberation. (See also: Yo Soy 132)
- January 26: Anonymous defaced the website of the United States Sentencing Commission multiple times following the suicide of Aaron Swartz, causing the site to crash under heavy traffic. Swartz had been accused of stealing materials from the Massachusetts Institute of Technology with intent to distribute them freely.
- February 3: Anonymous hacked the Federal Reserve and released data obtained from the breach.
- March: During the 2013 Lahad Datu standoff, cyberattacks were exchanged between Philippine and Malaysian hacking groups. Philippine sources reported that Malaysian hackers defaced Philippine websites and posted threats. In response, the Philippine Cyber Army defaced 175 Malaysian websites, including state-owned pages. McAfee researchers later listed the Philippine Cyber Army as a global hacktivist threat, noting its ties to Anonymous.
- April: After Cleveland police fired 137 rounds at a car in December 2012, killing its two occupants, Anonymous released personal information of the officers involved in April 2013. Twelve officers were later fired or disciplined, and criminal charges were considered by a grand jury.
- April 2: Anonymous announced "Operation Free Korea," calling for political changes in North Korea and threatening cyberattacks if demands were not met. On April 3, the group claimed to have stolen 15,000 user passwords. On April 4, Anonymous claimed responsibility for hacking the Uriminzokkiri website and its associated Twitter and Flickr accounts. A defaced image of Kim Jong Un was posted on the group's Flickr page, and The Jester (hacktivist) separately claimed attacks on Air Koryo and other North Korean sites. On June 22, Anonymous claimed to have stolen North Korean military documents and said they would be released on June 25, though no documents were published. (See also: 2013 Korean crisis and Cyberactivism in North Korea)
- April 6: (OpIsrael) Anonymous-affiliated groups and other anti-Israel actors carried out coordinated cyberattacks against Israeli websites to coincide with Holocaust Remembrance Day. The campaign consisted mainly of denial of service attacks and targeted government, banking, media, and small business websites. Most attacks were repelled, though the Central Bureau of Statistics site may have been briefly taken offline. Some sites were defaced with anti-Israel slogans, while various social media accounts associated with the attackers made false claims of large-scale damage, including fabricated financial losses and nationwide outages. Israeli hackers responded by taking down the OpIsrael website, replacing it with pro-Israel messages and the national anthem Hatikvah, and by targeting sites associated with Hezbollah, Islamic Jihad, and individuals involved in the operation.
- April 12: Following the suicide of Rehtaeh Parsons, Anonymous threatened to release personal information about individuals alleged to have assaulted her, but later withdrew the threat after a request from Parsons' mother. The group also held protests outside the Royal Canadian Mounted Police headquarters in Halifax. (See also:
Anonymous muscle in on Canadian teen rape case at Wikinews)
- May 10: After a Philippine Coast Guard vessel fired on the Taiwanese fishing boat Guang Da Xing No. 28 on May 9, killing a fisherman, hackers identifying as "AnonTAIWAN" attacked Philippine government websites and leaked account information. The attacks caused disruptions to government websites during the Philippine general election.
- May 28: Anonymous published personal information belonging to members of the English Defence League (a far right street protest movement) in what the group described as an effort to destroy the organization.
- June 7: Anonymous released documents they described as secret NSA files, though the materials were already publicly available.
- June 30: After a Hawthorne, California police officer shot a dog during an arrest, Anonymous issued a video threat directed at the police department. The city website also experienced a DDoS attack, though it is unclear whether Anonymous was responsible.
- July 4: Anonymous hacked the national website of Nigeria after the passage of legislation imposing prison sentences of up to 14 years for same-sex relationships.
- July: Anonymous NZ conducted DDoS attacks on the website of the Government Communications Security Bureau, websites linked to the New Zealand National Party, and on websites belonging to politicians who supported legislation expanding the agency's surveillance powers.
- August–November: (Operation Singapore) Between August 20 and November 5, Anonymous carried out attacks on multiple Singaporean websites, including those of Ang Mo Kio Town Council, the National Museum of Singapore—from which they leaked 3,600 emails, IP addresses, and names—PAP Community Foundation, and The Straits Times. (See also: 2013 Singapore cyberattacks)
- November: Anonymous Philippines hacked 115 government websites during protests against the Priority Development Assistance Fund (PDAF), prompting investigations by Philippine law enforcement agencies. The NBI was ordered to investigate the attacks. Some senators downplayed the incidents but acknowledged the grievances raised, while Senator Trillanes IV expressed concern about the potential impact of such attacks on government systems.