OpenSSL Fixes HollowByte Memory Exhaustion Bug
Okta disclosed HollowByte, an 11-byte OpenSSL flaw that lets remote attackers exhaust server memory and trigger denial-of-service attacks. Okta’s Red Team disclosed a denial-of-service vulnerability in OpenSSL they named HollowByte, and the attack payload is exactly 11 bytes. A remote, unauthenticated attacker sends that payload and the server allocates up to 131 KB of memory […]
Okta’s Red Team disclosed a denial-of-service vulnerability in OpenSSL they named HollowByte, and the attack payload is exactly 11 bytes. A remote, unauthenticated attacker sends that payload and the server allocates up to 131 KB of memory before the TLS handshake even begins, then blocks a worker thread waiting for data that never arrives. No credentials required, no prior access, no exploit chain.
“When a rogue header lands, the state machine triggers an unvalidated allocation.” reads the advisory. “When the malicious 11-byte payload arrives, the TLS state machine reads the 4-byte handshake header and triggers an unvalidated pre-allocation based on the header’s 3-byte length declaration:
Source: https://securityaffairs.com/195588/hacking/openssl-fixes-hollowbyte-memory-exhaustion-bug.html
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