Knowledge vs Information

One way to conceptualize the difference between knowledge and information is this: knowledge involves some metric of computational difficulty to arrive at, while mere information lacks this property.

mapcidr patch

Project Discovery’s mapcidr had a bug when converting IP addresses. The “-ip-format” flag did not properly work for one of the cases. For example, echo '127.0.0.1' | mapcidr -ip-format 5 would incorrectly return the integer representation or decimal value 281472812449793, when it should have returned the decimal value 2130706433. The problem could be seen in the Go function here which uses functionality imported from the math library.

func IPToInteger(ip net.IP) (*big.Int, int, error) {
	val := &big.Int{}
	val.SetBytes([]byte(ip))

	if len(ip) == net.IPv4len {
		return val, 32, nil //nolint
	} else if len(ip) == net.IPv6len {
		return val, 128, nil //nolint
	} else {
		return nil, 0, fmt.Errorf("unsupported address length %d", len(ip))

The function was easily fixed by removing the early "setBytes" value and rewriting it to correctly set the bytes conditionally for each if-statement, depending on the IP type.

func IPToInteger(ip net.IP) (*big.Int, int, error) {

	val := new(big.Int)

	// check if the ip is v4 => convert to 4 bytes representation
	if ipv4 := ip.To4(); ipv4 != nil {
		val.SetBytes(ipv4)
		return val, 32, nil
	}

	// check if the ip is v6 => convert to 16 bytes representation
	if ipv6 := ip.To16(); ipv6 != nil {
		val.SetBytes(ipv6)
		return val, 128, nil
	}

	return nil, 0, fmt.Errorf("unsupported IP address format")
}

Pull request #258.

DMARC

Lately I've overheard some people discussing email spoofing with regard to organizations that don't implement DMARC. Namely, "APTs" taking advantage of organizations that don't utilize Domain-based Message Authentication, Reporting and Conformance.

Enumerating TLS Certificates with jq and Bash

Doubling back to share some more notes about web application security adjacent stuff. This is a bash script for reconnaissance that uses some tooling from Project Discovery - mapcidr and tlsx - in combination with jq and Bash, to enumerate TLS certificates.

Using Bash to Sort IPs by Subnet Uniqueness

This is a helpful Bash script to parse IP addresses by the uniqueness of their subnets. This can be quite helpful in various scenarios.

Binary, IPv4, and Subnets

The IPv4 protocol which we broadly (but not totally) use today rests on an addressing system that was designed in the 1970s and formally published in 1980.

The Etymology of 'Deadline'

The word 'deadline' has a popular etymology story around 19th century prison culture. The explanation of the meaning behind the word 'deadline' often goes something like this — as many etymologists and US dictionaries frequently cite it: