• Home
  • Latest
  • Fortune 500
  • Finance
  • Tech
  • Leadership
  • Lifestyle
  • Rankings
  • Multimedia
TechDeloitte

Deloitte Gets Hacked: What We Know So Far

Jeff John Roberts
By
Jeff John Roberts
Jeff John Roberts
Editor, Finance and Crypto
Down Arrow Button Icon
Jeff John Roberts
By
Jeff John Roberts
Jeff John Roberts
Editor, Finance and Crypto
Down Arrow Button Icon
September 25, 2017, 6:17 PM ET

A bombshell report on Monday revealed that Deloitte was hit by a major cyber attack that compromised its email system and certain client records. The news is a major black eye for one of the world’s “big four” accountancy and consulting firms—especially since a major part of Deloitte’s business is selling cyber security.

The full extent of the hacking episode isn’t clear, but details are beginning to trickle out, including from Brian Krebs, a well-respected security journalist who says he has heard from sources close to the Deloitte. Here’s a Q&A about we know and don’t know about the latest high profile security attack.

What did the hackers steal?

The initial report of the Deloitte breach came from the Guardian, which revealed hackers had compromised the “confidential emails and plans of some of its blue-chip clients.” In response, the firm confirmed it had suffered a cyber-attack, but played down the significance by saying “only very few clients were impacted.”

Krebs, however, cites sources close to Deloitte who suggest the hack was likely more severe than that. The sources claimed the hackers accessed the entirety of the firm’s internal email database, and all administrative accounts. Worse, it appears the hackers transferred or copied a significant amount of that confidential data:

This same source said forensic investigators identified several gigabytes of data being exfiltrated to a server in the United Kingdom. The source further said the hackers had free reign in the network for “a long time” and that the company still does not know exactly how much total data was taken.

Meanwhile, Krebs’ sources say Deloitte has yet to identify the full pervasiveness of the attack.

What companies are affected?

Deloitte has only said it notified six companies and some government agencies, but it has not identified them. The Guardian adds that those companies are household names, but likewise doesn’t provide further details.

A firm like Deloitte advises giant multinationals in sectors like finance, pharma, and media, so the length of potential victims is long. It’s also possible the list of actual victims will come to number more than six—especially if Deloitte has yet to get to the bottom of the hack.

How bad is this?

For Deloitte, it’s very bad. The reputation of company’s cyber-security consulting business will take a hit, and not just because it got breached. If details in the Guardian’s report are true, Deloitte failed to deploy elementary security measures such as requiring two-factor authentication. The firm also appears to have guarded large pools of data with a single password.

For Deloitte’s clients, the extent of the harm is less clear. If hackers indeed got hold of all of Deloitte’s emails, those messages may have revealed their client’s secret corporate strategies or sensitive intellectual property. Meanwhile, all of those email addresses would provide crooks with ample opportunities for spear-phishing scams targeted at top executives.

Who are the hackers?

No one has claimed responsibility, but the nature of the attacks suggest the hackers were commercially motivated, and seeking confidential information to sell or use for insider trading. This fits the pattern of Russian criminal gangs who plot jobs in secret Internet forums, as well as hackers sponsored by the Chinese government—as Fortune reported last year, China was behind a series of infiltrations targeting white shoe law firms and their clients.

When will we know more?

Reports suggests Deloitte knew something was amiss as long ago as last October so the firm almost certainly knows more than it is disclosing. In response to the Guardian’s report, the company issued a statement but has yet to address the additional details described by Krebs.

Look for more information to trickle out in coming days from the company, but also in the form of leaks from the security community and beyond.

About the Author
Jeff John Roberts
By Jeff John RobertsEditor, Finance and Crypto
LinkedIn iconTwitter icon

Jeff John Roberts is the Finance and Crypto editor at Fortune, overseeing coverage of the blockchain and how technology is changing finance.

See full bioRight Arrow Button Icon

Latest in Tech

Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025

Most Popular

Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Finance
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam
By Fortune Editors
October 20, 2025
Fortune Secondary Logo
Rankings
  • 100 Best Companies
  • Fortune 500
  • Global 500
  • Fortune 500 Europe
  • Most Powerful Women
  • Future 50
  • World’s Most Admired Companies
  • See All Rankings
Sections
  • Finance
  • Fortune Crypto
  • Features
  • Leadership
  • Health
  • Commentary
  • Success
  • Retail
  • Mpw
  • Tech
  • Lifestyle
  • CEO Initiative
  • Asia
  • Politics
  • Conferences
  • Europe
  • Newsletters
  • Personal Finance
  • Environment
  • Magazine
  • Education
Customer Support
  • Frequently Asked Questions
  • Customer Service Portal
  • Privacy Policy
  • Terms Of Use
  • Single Issues For Purchase
  • International Print
Commercial Services
  • Advertising
  • Fortune Brand Studio
  • Fortune Analytics
  • Fortune Conferences
  • Business Development
About Us
  • About Us
  • Editorial Calendar
  • Press Center
  • Work At Fortune
  • Diversity And Inclusion
  • Terms And Conditions
  • Site Map
Fortune Secondary Logo
  • About Us
  • Editorial Calendar
  • Press Center
  • Work At Fortune
  • Diversity And Inclusion
  • Terms And Conditions
  • Site Map
  • Facebook icon
  • Twitter icon
  • LinkedIn icon
  • Instagram icon
  • Pinterest icon

Latest in Tech

roth
CommentaryLeadership
The AI resource reallocation challenge: How can companies capture the value of time?
By Erik RothFebruary 27, 2026
2 hours ago
Nvidia CEO Jensen Huang during the Nvidia GTC keynote address at the SAP Center
InvestingMarkets
U.S. stocks are being battered by ‘AI derangement syndrome,’ and CEOs are learning not to talk about it
By Jim EdwardsFebruary 27, 2026
2 hours ago
NewslettersTerm Sheet
Exclusive: Flux, backed by 8VC, raises $37 million to vibe code electronics
By Allie GarfinkleFebruary 27, 2026
3 hours ago
NewslettersFortune Tech
Salesforce’s Marc Benioff does not fear the ‘SaaS-pocalypse’
By Alexei OreskovicFebruary 27, 2026
4 hours ago
Chinese students working on laptops
SuccessCareers
Walmart exec says the U.S. needs to get tougher on training its next generation of workers in AI: ‘Look at China, 5-year-olds are learning DeepSeek’
By Preston ForeFebruary 27, 2026
5 hours ago
broker
EconomyMarkets
Citadel Securities demolishes viral AI doomsday essay, arguing the real ‘Global Intelligence Crisis’ is ignorance of macro fundamentals
By Nick LichtenbergFebruary 26, 2026
16 hours ago

Most Popular

placeholder alt text
Innovation
An MIT roboticist who cofounded bankrupt robot vacuum maker iRobot says Elon Musk’s vision of humanoid robot assistants is ‘pure fantasy thinking’
By Marco Quiroz-GutierrezFebruary 25, 2026
2 days ago
placeholder alt text
Success
Jeff Bezos says being lazy, not working hard, is the root of anxiety: ‘The stress goes away the second I take that first step’
By Sydney LakeFebruary 25, 2026
2 days ago
placeholder alt text
Economy
Trump claims America is ‘winning so much.’ The IMF agrees, adding that Trump’s trade policies are the only thing holding it back from even more
By Tristan BoveFebruary 26, 2026
18 hours ago
placeholder alt text
Success
Gen Z Olympic champion Eileen Gu says she rewires her brain daily to be more successful—and multimillionaire founder Arianna Huffington says it really does work
By Orianna Rosa RoyleFebruary 25, 2026
2 days ago
placeholder alt text
AI
Jamie Dimon says society should start preparing for AI job displacement: ‘Now’s the time to start thinking about’ it
By Marco Quiroz-GutierrezFebruary 25, 2026
2 days ago
placeholder alt text
Success
Ex–presidential candidate Andrew Yang warns that millions of white-collar workers will lose their jobs within 18 months: ‘The AI jobpocalypse is here’
By Preston ForeFebruary 25, 2026
2 days ago

© 2026 Fortune Media IP Limited. All Rights Reserved. Use of this site constitutes acceptance of our Terms of Use and Privacy Policy | CA Notice at Collection and Privacy Notice | Do Not Sell/Share My Personal Information
FORTUNE is a trademark of Fortune Media IP Limited, registered in the U.S. and other countries. FORTUNE may receive compensation for some links to products and services on this website. Offers may be subject to change without notice.