ZAP! — metactf

Description

Identify the exact NIA ST number of a porcelain electrical insulator from photos.

English summary: the challenge provides several photos of a porcelain suspension insulator and asks for the exact NIA standards number.

Analysis

The assets came from the public DawgCTF spring repository challenge folder for ZAP! (I,II). The photos show a porcelain suspension-disc insulator with a rusty cap/clevis, central pin, and a multi-ring underside.

Recon narrowed it to the 10-inch porcelain suspension family. The hint to focus on small details was important: the answer was not just the general object class, but the exact NIA variant.

• 10-inch class suspension disc silhouette
• incuse LOCKE marking
• engraving/order consistent with 10000 TEST / 20000 M&E
• inset ceramic geometry that differed from nearby ST-4626 variants

The main candidates were ST-4626, ST-4625B, ST-4626A, ST-4626E, ST-3524, ST-4638, ST-4625, and ST-4626F. Previously tested variants ST-4626, ST-4625B, ST-4626A, and ST-4626E were rejected, so the comparison had to focus on engraving order and the way the ceramic body sat inside the cap.

The final match was ST-4626F, whose NIA description fits the observed details in the same 10-inch family:

• LOCKE / 10000 TEST / 20000 M&E

That marking order, together with the inset geometry, distinguishes it from ST-4626 and other nearby catalog entries. This was a catalog-comparison OSINT task, not a generic reverse image search task.

Solution

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