Proxy-url-file-3a-2f-2f-2f May 2026

Squid access logs might show: 1698741234.123 0 TCP_DENIED/400 3818 GET proxy-url-file:///invalid - HIER_NONE/- text/html If the log formatter escapes slashes, you'd see proxy-url-file-3A-2F-2F-2Finvalid.

proxy-url-file-3A-2F-2F-2F

If we interpret 3A as %3A and 2F as %2F, we can rewrite the string as: proxy-url-file-3A-2F-2F-2F

proxy-url-file-%3A%2F%2F%2F

Now decode the percent-encoded part:

%3A → :
%2F → /
%2F → /
%2F → /

Result: proxy-url-file:///

If you need the actual URL that was intended:

Manual restoration: proxy-url-file-3A-2F-2F-2F → proxy-url-file%3A%2F%2F%2F → Decode → proxy-url-file:/// Squid access logs might show: 1698741234

Attackers sometimes inject encoded strings to bypass WAF (Web Application Firewall) rules. Seeing 3A-2F-2F-2F instead of :/// might slip past naive filters.