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CID-4118: Validate webhook signature #136

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Merged
mohamedlajmileanix merged 1 commit into from
Jul 31, 2025
Merged

CID-4118: Validate webhook signature #136

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7 changes: 7 additions & 0 deletions src/main/kotlin/net/leanix/githubagent/services/GitHubWebhookService.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,13 @@ class GitHubWebhookService(
logger.error("Invalid signature format, expected 'sha256=' prefix")
throw InvalidEventSignatureException()
}

val signatureWithoutPrefix = signature256.removePrefix("sha256=")
if (!signatureWithoutPrefix.matches(Regex("^[a-fA-F0-9]{64}$"))) {
logger.error("Invalid signature format, expected a 64-character hexadecimal string after 'sha256='")
throw InvalidEventSignatureException()
}

val hashedSecret = hmacSHA256(gitHubEnterpriseProperties.webhookSecret, payload)
val isEqual = timingSafeEqual(signature256.removePrefix("sha256="), hashedSecret)
if (!isEqual) throw InvalidEventSignatureException()
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23 changes: 23 additions & 0 deletions src/test/kotlin/net/leanix/githubagent/services/GitHubWebhookServiceTest.kt
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Expand Up @@ -99,4 +99,27 @@ class GitHubWebhookServiceTest {
gitHubWebhookService.handleWebhookEvent("PUSH", "known.host", "invalid_signature", "{}")
}
}

@Test
fun `should process event with valid signature from event json`() {
val payload = """{
"action": "created",
"installation": {
"id": 30,
"account": {
"login": "test-org",
"id": 20
}
}
}"""
val secret = "secret"
val validSignature = "sha256=042fb14dec4f623e224b1b574e40ff776c341fcd883756256d786a1b95bb3aa8"
every { gitHubEnterpriseProperties.baseUrl } returns "known.host"
every { gitHubEnterpriseProperties.webhookSecret } returns secret
every { webhookEventService.consumeWebhookEvent(any(), any()) } returns Unit

gitHubWebhookService.handleWebhookEvent("PUSH", "known.host", validSignature, payload)

verify { webhookEventService.consumeWebhookEvent("PUSH", payload) }
}
}
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