NullBulge says motive is to expose potential corporate malpractices
Ticketmaster says it uses dynamic barcodes that refresh every few seconds
Group says it carried out a penetration test 'with post-payment'
Other leaked data includes ID documents, payment information and phone numbers
But no sensitive data was compromised
ShinyHunters claims to have credit card numbers for 28 million individuals
Company says compromised data originated from a third-party vendor
Hackers posted dozens of confidential documents on dark web
Patches have been made available by Ivanti