In the World of AI: Week of 21 July 2026, A Worm Hidden in Copilot for Word

A security researcher has shown that hidden instructions can spread between Word documents through Copilot, a free national AI helpline has opened for small businesses, and the tax regulator has set out how tax professionals may use AI. This is the week from 22 to 28 July 2026, with one step for each story.

1. A worm can spread between Word documents through Copilot

Norwegian researcher Håkon Måløy published his findings on 28 July. He hid instructions in a document, such as white text in a small font. When a victim uses that document as source material in Copilot for Word, Copilot follows the instructions, and in his proof of concept it halved the financial figures in a report. It also copies the hidden instructions into the new document, which becomes a carrier, so the original file is no longer needed. Måløy says Microsoft confirmed the behaviour and shipped fixes on 3 April and 14 July, but he reproduced the broader attack with modified payloads and reports that no robust mitigation for the broader vulnerability class is available.

Why it matters: The risk is quiet changes to numbers in documents that look normal, such as quotes, budgets and reports. Reading the output is the main defence available to you.

This week: Treat documents from outside your business as untrusted before Copilot uses them, and check anything Copilot has edited before you send it. Our guide to human review for AI output sets out a simple routine.

2. A free national AI helpline opens for small businesses

Technology Decisions reported on 22 July that SMEC AI, a federally backed body, has launched a free AI Information Line under the government's AI Adopt program, co-hosted with the National AI Centre. IT Brief's account says an AI voice agent takes a plain-language description of a business problem, suggests general AI options and texts a summary of next steps. The line identifies itself as an AI assistant, gives general information rather than professional, legal, financial or tax advice, and says it takes no commissions from providers it mentions. The number is 1800 517 403.

Why it matters: It is a free place to test an idea before you spend money, with the limits that come from a general-purpose service.

This week: If you have a specific problem in mind, call with the problem described in general terms, and keep client names and figures out of the conversation.

3. The Tax Practitioners Board issues AI guidance

SMS Magazine reported on 23 July that the Tax Practitioners Board has issued a guidance statement explaining how the Code of Professional Conduct applies when tax practitioners use AI. It covers competence, reasonable care, confidentiality, record-keeping, professional judgment and supervision. Practitioners generally need each client's permission before sharing client information with a third party, and the statement says that can include entering client data into AI tools, depending on how they are configured and used. AI should support rather than replace professional judgment, and practitioners stay accountable for their services.

Why it matters: If your tax agent or BAS agent uses AI, your financial information may be going into it. The guidance makes clear that permission and care apply.

This week: Ask your tax or BAS agent whether they use AI tools with client data and what controls they have. The same question applies inside your own business, which our answer on staff pasting confidential data into AI covers. This is general information, so get advice on your own situation.

4. Anthropic launches Claude Opus 5

VentureBeat reported that Anthropic released Claude Opus 5 on Friday 24 July. The API price is $5 per million input tokens and $25 per million output tokens, the same as Opus 4.8. It is the new default on Claude Max and the strongest model on Claude Pro. Anthropic says it comes near Fable 5's intelligence at about half the cost, while acknowledging that Fable 5 remains its most capable model. The benchmark scores in the report are the company's own.

Why it matters: A new model usually arrives with strong claims from its maker. The claims come from benchmark tests, which say little about your invoices or customer emails.

This week: Take five real examples of work your team does with AI, run them through your current model and the new one, and compare. Our guide to measuring whether AI is working shows how.

What to do this week

• Check anything Copilot has edited before it leaves your business.
• Treat documents from outside your business as untrusted before Copilot uses them.
• Decide whether the free AI helpline is worth a call, keeping client details out of it.
• Ask your tax or BAS agent how they handle client data in AI tools.
• Test any new model on five real tasks before switching.

Sources

• Håkon Måløy, "Context Collapse, Part 3: AI Worming through Word", 28 July 2026: enklypesalt.com
• Technology Decisions, "Government launches AI adoption advice hotline for SMEs", 22 July 2026: technologydecisions.com.au
• IT Brief Australia, "SMEC AI launches national line to aid SME AI adoption", 22 July 2026: itbrief.com.au
• SMS Magazine, "TPB releases AI guidance for members", 23 July 2026: smsmagazine.com.au
• VentureBeat, "Anthropic launches Claude Opus 5, a cheaper AI model for coding, agents and enterprise workflows", 24 July 2026: venturebeat.com