{
	"id": "c814f72f-4b3c-4fae-814a-44025464e01e",
	"created_at": "2026-04-06T00:18:44.423403Z",
	"updated_at": "2026-04-10T13:11:41.620735Z",
	"deleted_at": null,
	"sha1_hash": "ee106013b53811e01ad1552b629594e4f6c468dc",
	"title": "Replay Attack | Bugcrowd",
	"llm_title": "",
	"authors": "",
	"file_creation_date": "0001-01-01T00:00:00Z",
	"file_modification_date": "0001-01-01T00:00:00Z",
	"file_size": 57853,
	"plain_text": "Replay Attack | Bugcrowd\r\nArchived: 2026-04-05 20:31:51 UTC\r\nA replay attack is a form of network attack in which cyber attackers identify and detect a data transmission and\r\nthen delay it or repeat it. The data transmission is delayed or repeated by the cyber attacker. Once the data is\r\nintercepted, it is retransmitted to the original destination, where the attacker now pretends to be the original\r\nsender. The party receives the authenticated message, but it is the message sent by the attacker. Of course, the\r\nmessage is received twice – this is why it is called a replay attack. The replay attack is particularly harmful in that\r\nthe cyber attacker need not even decrypt the message they resend. However, they can still deceive the message\r\nrecipient into believing that the received message is legitimate. Replay attacks enable cyber attackers to access\r\ntargeted networks where they can access information that would not have been easily accessible. \r\nHow would a Replay Attack Work?\r\nIn this hypothetical example, Party A wants to request that Party B transfer $100 to Party A’s account. Party A\r\nsends a legitimate message to Party B in support of this request. Since Party B believes that Party A’s request is\r\nhttps://www.bugcrowd.com/glossary/replay-attack/\r\nPage 1 of 3\n\nlegitimate, Party B sends the amount requested. \r\nInstead, Party A’s initial transfer message was intercepted by a cyber attacker that, in turn, resends the message to\r\nParty B. Once again, Party B thinks the message is from Party A, so Party B transfers the amount requested again.\r\nHowever, this time, Party B transmits the amount of money requested to the cyber attacker, not Party A. This is\r\none example of how replay attacks can be used.\r\nNetworks and computers vulnerable to replay attacks will determine the attack process as legitimate messages.\r\nOne example of a replay attack is to replay the message sent to a network by an attacker, which an authorized user\r\nearlier sent. Consider that the messages might be encrypted. A replay attack provides access to valuable resources\r\nby replaying an authentication message and confusing the recipient host.\r\nHow can Replay Attacks be Prevented?\r\nOne best practice in defense of the replay attack is to provide timestamps or sequence numbers for each message\r\nsent. Recipients can then identify a message with a repeated timestamp or sequence number and then discard it.\r\nAnother best practice is the use of digital signatures. Digital signatures allow the recipient to authenticate the\r\nsender. \r\nAnother best practice to mitigate replay attacks is to use random-session session keys. Random-session keys are\r\ngenerally time-specific. Therefore, these keys will change over time, making it difficult for the cyber attacker to\r\ndeceive a recipient.\r\nOne-time passwords are another excellent best practice that can also be used to mitigate replay attacks. A one-time\r\npassword is an automatically generated alphanumeric string of characters that authenticates a user for only one\r\ntransaction or login session. One-time passwords are much more secure than typical passwords.\r\nHow Does the Internet Protocol Security (IPsec) Impact Replay Attacks?\r\nIPsec is a suite of protocols and algorithms that secure data transmitted over the internet. The IETF developed\r\nIPsec protocols to secure the IP layer using authentication and encryption of IP network packets. IPsec’s first\r\ndefinitions referred to two protocols to secure IP packets. These included the Authentication Header for data\r\nintegrity and anti-replay services and the Encapsulating Security Payload, which encrypts and authenticates data. \r\nThe IPsec suite also includes an Internet Key Exchange used to generate shared security keys to establish a\r\nsecurity association. Security associations are used by the encryption and decryption processes to create a security\r\nlevel between two entities. Typically, a firewall between two networks handles the security association process.\r\nWant to learn more? Check out our FREE Bugcrowd University to sharpen your hacking skills.\r\nOrganizations the world over need your help! Join our researcher community to connect with hundreds of\r\norganization programs focused on finding their security vulnerabilities. Our vast directory includes programs for\r\nall skill levels across many industries and from around the world.\r\nhttps://www.bugcrowd.com/glossary/replay-attack/\r\nPage 2 of 3\n\nSource: https://www.bugcrowd.com/glossary/replay-attack/\r\nhttps://www.bugcrowd.com/glossary/replay-attack/\r\nPage 3 of 3",
	"extraction_quality": 1,
	"language": "EN",
	"sources": [
		"MITRE"
	],
	"origins": [
		"web"
	],
	"references": [
		"https://www.bugcrowd.com/glossary/replay-attack/"
	],
	"report_names": [
		"replay-attack"
	],
	"threat_actors": [],
	"ts_created_at": 1775434724,
	"ts_updated_at": 1775826701,
	"ts_creation_date": 0,
	"ts_modification_date": 0,
	"files": {
		"pdf": "https://archive.orkl.eu/ee106013b53811e01ad1552b629594e4f6c468dc.pdf",
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		"img": "https://archive.orkl.eu/ee106013b53811e01ad1552b629594e4f6c468dc.jpg"
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}