Information Exposure

Affecting openssl1.0 package, versions <1.0.2r-1~deb9u1

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Overview

If an application encounters a fatal protocol error and then calls SSL_shutdown() twice (once to send a close_notify, and once to receive one) then OpenSSL can respond differently to the calling application if a 0 byte record is received with invalid padding compared to if a 0 byte record is received with an invalid MAC. If the application then behaves differently based on that in a way that is detectable to the remote peer, then this amounts to a padding oracle that could be used to decrypt data. In order for this to be exploitable "non-stitched" ciphersuites must be in use. Stitched ciphersuites are optimised implementations of certain commonly used ciphersuites. Also the application must call SSL_shutdown() twice even if a protocol error has occurred (applications should not do this but some do anyway). Fixed in OpenSSL 1.0.2r (Affected 1.0.2-1.0.2q).

References

CVSS Score

5.9
medium severity
  • Attack Vector
    Network
  • Attack Complexity
    High
  • Privileges Required
    None
  • User Interaction
    None
  • Scope
    Unchanged
  • Confidentiality
    High
  • Integrity
    None
  • Availability
    None
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
CVE
CVE-2019-1559
CWE
CWE-203
Snyk ID
SNYK-DEBIAN9-OPENSSL10-338102
Disclosed
27 Feb, 2019
Published
27 Feb, 2019