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REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4541
REF: https://www.rfc-editor.org/rfc/rfc1948.txt
REF: https://www.rfc-editor.org/rfc/rfc6528.txt
REF: https://www.rfc-editor.org/rfc/rfc9293.txt
Bug Overview:
PixieFail Bug #8
CVE-2023-45236
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N
CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
Updates TCP ISN generation to use a cryptographic hash of the
connection's identifying parameters and a secret key.
This prevents an attacker from guessing the ISN used for some other
connection.
This is follows the guidance in RFC 1948, RFC 6528, and RFC 9293.
RFC: 9293 Section 3.4.1. Initial Sequence Number Selection
A TCP implementation MUST use the above type of "clock" for clock-
driven selection of initial sequence numbers (MUST-8), and SHOULD
generate its initial sequence numbers with the expression:
ISN = M + F(localip, localport, remoteip, remoteport, secretkey)
where M is the 4 microsecond timer, and F() is a pseudorandom
function (PRF) of the connection's identifying parameters ("localip,
localport, remoteip, remoteport") and a secret key ("secretkey")
(SHLD-1). F() MUST NOT be computable from the outside (MUST-9), or
an attacker could still guess at sequence numbers from the ISN used
for some other connection. The PRF could be implemented as a
cryptographic hash of the concatenation of the TCP connection
parameters and some secret data. For discussion of the selection of
a specific hash algorithm and management of the secret key data,
please see Section 3 of [42].
For each connection there is a send sequence number and a receive
sequence number. The initial send sequence number (ISS) is chosen by
the data sending TCP peer, and the initial receive sequence number
(IRS) is learned during the connection-establishing procedure.
For a connection to be established or initialized, the two TCP peers
must synchronize on each other's initial sequence numbers. This is
done in an exchange of connection-establishing segments carrying a
control bit called "SYN" (for synchronize) and the initial sequence
numbers. As a shorthand, segments carrying the SYN bit are also
called "SYNs". Hence, the solution requires a suitable mechanism for
picking an initial sequence number and a slightly involved handshake
to exchange the ISNs.
Cc: Saloni Kasbekar <saloni.kasbekar@intel.com>
Cc: Zachary Clark-williams <zachary.clark-williams@intel.com>
Signed-off-by: Doug Flick [MSFT] <doug.edk2@gmail.com>
Reviewed-by: Saloni Kasbekar <saloni.kasbekar@intel.com>
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REF:https://bugzilla.tianocore.org/show_bug.cgi?id=4542
Bug Overview:
PixieFail Bug #9
CVE-2023-45237
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CWE-338 Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)
Use of a Weak PseudoRandom Number Generator
Change Overview:
Updates all Instances of NET_RANDOM (NetRandomInitSeed ()) to either
>
> EFI_STATUS
> EFIAPI
> PseudoRandomU32 (
> OUT UINT32 *Output
> );
>
or (depending on the use case)
>
> EFI_STATUS
> EFIAPI
> PseudoRandom (
> OUT VOID *Output,
> IN UINTN OutputLength
> );
>
This is because the use of
Example:
The following code snippet PseudoRandomU32 () function is used:
>
> UINT32 Random;
>
> Status = PseudoRandomU32 (&Random);
> if (EFI_ERROR (Status)) {
> DEBUG ((DEBUG_ERROR, "%a failed to generate random number: %r\n",
__func__, Status));
> return Status;
> }
>
This also introduces a new PCD to enable/disable the use of the
secure implementation of algorithms for PseudoRandom () and
instead depend on the default implementation. This may be required for
some platforms where the UEFI Spec defined algorithms are not available.
>
> PcdEnforceSecureRngAlgorithms
>
If the platform does not have any one of the UEFI defined
secure RNG algorithms then the driver will assert.
Cc: Saloni Kasbekar <saloni.kasbekar@intel.com>
Cc: Zachary Clark-williams <zachary.clark-williams@intel.com>
Signed-off-by: Doug Flick [MSFT] <doug.edk2@gmail.com>
Reviewed-by: Saloni Kasbekar <saloni.kasbekar@intel.com>
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