Ukrposhta

It was a DDoS (distributed denial-of-service) attack that caused such disruptions.

Ukrposhta along with internet providers tried to restore both the online store and systems.

However, Moscow has been consistently denying accusations it has launched cyberattacks on Ukraine.

Source: https://www.reuters.com/world/europe/ukraines-postal-service-hit-by-cyberattack-after-sales-warship-stamp-go-online-2022-04-22/

TPRM report: https://scoringcyber.rankiteo.com/company/ukrposhta

"id": "ukr04123422",
"linkid": "ukrposhta",
"type": "Cyber Attack",
"date": "04/2022",
"severity": "100",
"impact": "9",
"explanation": "Attack that could bring to a war"

{'affected_entities': [{'industry': 'Postal and Logistics',
                        'location': 'Ukraine',
                        'name': 'Ukrposhta',
                        'type': 'Government-owned postal service'}],
 'attack_vector': 'DDoS',
 'description': 'A DDoS (distributed denial-of-service) attack caused '
                "significant disruptions to Ukrposhta's online store and "
                'systems.',
 'impact': {'operational_impact': 'Significant disruptions',
            'systems_affected': ['Online store', 'Internal systems']},
 'motivation': 'Disruption of services',
 'response': {'recovery_measures': 'Attempted to restore both the online store '
                                   'and systems',
              'third_party_assistance': 'Internet providers'},
 'threat_actor': 'Unspecified, with Moscow denying involvement',
 'title': 'DDoS Attack on Ukrposhta',
 'type': 'DDoS Attack'}