A Suspicious Supplier Email, a Reorder Column and a Stale Backup
A workshop store tracks consumables in a spreadsheet with columns A Item, B Unit, C Quantity in stock, D Reorder level and E Status; data runs from row 2 to row 41. On Monday morning the store clerk, who has had no computer training, receives an email that appears to come from an approved supplier: 'Please find attached invoice.exe for the electrode consignment. Kindly open and update our new bank account number before today's payment run.' The message is addressed to 'Dear Customer', the supplier's usual address ends with co.in but this one is written with a hyphen, and the sender asks the clerk to keep the matter confidential from the accounts officer. The clerk has already downloaded the file and asks you whether to open it. He also wants to know how the sheet can mark items that have fallen to or below the reorder level. There is no IT support within 30 km, and the store's only backup was taken four months ago.
1. List the phishing indicators in this email and set out exactly what the clerk should do now.
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Indicators. (1) The sender's domain is a lookalike, with a hyphen where the genuine domain has none. (2) The attachment is a program, invoice.exe, not a document; Windows often hides known extensions, so 'invoice.pdf.exe' can display as 'invoice.pdf'. (3) Generic salutation 'Dear Customer' instead of the usual named contact. (4) Manufactured urgency: 'before today's payment run'. (5) A request to change bank details, the classic payment-diversion pattern. (6) A demand for secrecy from the accounts officer, which is designed to bypass the one person who would check.
Action now. Do not open or run the file. Stop using that machine if the file has already been executed, and report immediately to the post commander and the nearest signals or IT detachment. Verify the supplier by telephone on a number already held in the ledger, never a number given in the email. Send the email headers and the file to the IT cell for analysis, then delete it from the mailbox and from the downloads folder. Record the incident in the store register. Any change of bank details must be authenticated by a documented call-back and a fresh cancelled-cheque or mandate verification before payment.
2. Write the formula the clerk needs in column E, explain what happens when it is copied down, and how to get a count of items needing reorder.
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Formula. In E2: =IF(C2<=D2,"REORDER","OK"). This compares the quantity in stock with the reorder level and returns the word REORDER when stock is at or below the level, which is the condition the clerk described; using < alone would miss the exact-equal case.
Copying down. C2 and D2 are relative references, so when the formula is filled down to E41 they become C3/D3, C4/D4 and so on. No dollar signs are needed because both references should shift row by row. If the formula is typed as text, the cell will show the formula itself; check that the cell is formatted as General, not Text. Text taken from another sheet may need TRIM to remove stray spaces.
Counting. =COUNTIF(E2:E41,"REORDER") gives the number of items to be indented. For visibility, also apply conditional formatting to E2:E41 so that REORDER cells turn red; the clerk then reads colours, not formulas. Lock the formula column so that it is not overwritten during data entry, and keep one blank template copy.
3. The last backup is four months old. Set out a realistic backup and record-keeping routine for a store with no local IT support.
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Immediate step. Make a fresh copy of the workbook today on a separate external drive, keep the existing file untouched, and check that the copy opens and the figures are intact. An untested backup is not a backup.
Routine. Follow the 3-2-1 idea in a simple form: the working file on the store computer, a daily copy on an external drive or pen drive kept separately from the machine, and a weekly copy handed to the office or uploaded to the unit's official storage if permitted. Keep at least four weekly copies rather than overwriting one file.
Naming. Include the date in the file name, for example store-stock-2025-06-02.xlsx, so that versions are obvious and an older version can be restored without confusion.
Controls. Store the external drive in a locked cupboard, away from heat and dust, and record in a register who took a backup and when. Restrict the formula column. When sending the rate list outside, convert to PDF so that rates cannot be edited, and use BCC for bulk mail so that recipients do not see each other's addresses.