OpenSSL up to 1.0.x crypto/mdc2/mdc2dgst.c MDC2_Update out-of-bounds write

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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8.4$0-$5k0.00

A vulnerability, which was classified as critical, was found in OpenSSL up to 1.0.x (Network Encryption Software). This affects the function MDC2_Update of the file crypto/mdc2/mdc2dgst.c. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. CWE is classifying the issue as CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Integer overflow in the MDC2_Update function in crypto/mdc2/mdc2dgst.c in OpenSSL before 1.1.0 allows remote attackers to cause a denial of service (out-of-bounds write and application crash) or possibly have unspecified other impact via unknown vectors.

The bug was discovered 09/16/2016. The weakness was shared 09/16/2016 by Shi Lei as Bug 1370146 as confirmed bug report (Bugzilla). It is possible to read the advisory at bugzilla.redhat.com. The vendor cooperated in the coordination of the public release. This vulnerability is uniquely identified as CVE-2016-6303 since 07/26/2016. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/19/2022). The reason for this vulnerability is this part of code: 

if (i + len < MDC2_BLOCK) {

The vulnerability was handled as a non-public zero-day exploit for at least 22 days. During that time the estimated underground price was around $25k-$100k. The vulnerability scanner Nessus provides a plugin with the ID 95917 (macOS 10.12.x < 10.12.2 Multiple Vulnerabilities), which helps to determine the existence of the flaw in a target environment. It is assigned to the family MacOS X Local Security Checks and running in the context c. The commercial vulnerability scanner Qualys is able to test this issue with plugin 316384 (Cisco Unity Express OpenSSL Multiple Vulnerabilities (cisco-sa-20160927-openssl)).

Upgrading to version 1.1.0 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at git.openssl.org. The best possible mitigation is suggested to be upgrading to the latest version. A possible mitigation has been published 4 months after the disclosure of the vulnerability. The vulnerability will be addressed with the following lines of code:

if (len < MDC2_BLOCK - i) {
The bug report contains the following remark:
MDC-2 support is not enabled in OpenSSL packages in Red Hat products. Therefore, this issue can not affect those packages.

The vulnerability is also documented in the vulnerability database at Tenable (95917). The entries 87463, 87879, 88080 and 90396 are related to this item.

Productinfo

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Support

  • end of life (old version)

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB CVSS-B Score: 🔍
VulDB CVSS-BT Score: 🔍
VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.5
VulDB Meta Temp Score: 8.4

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 9.8
NVD Vector: 🔍

CVSSv2info

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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Out-of-bounds write
CWE: CWE-787 / CWE-119
CAPEC: 🔍
ATT&CK: 🔍

Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 95917
Nessus Name: macOS 10.12.x < 10.12.2 Multiple Vulnerabilities
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

OpenVAS ID: 801105
OpenVAS Name: Apple Mac OS X Multiple Vulnerabilities-01 February-2017
OpenVAS File: 🔍
OpenVAS Family: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
Exposure Time: 🔍

Upgrade: OpenSSL 1.1.0
Patch: 55d83bf7c10c7b205fffa23fa7c3977491e56c07

Timelineinfo

07/26/2016 🔍
08/24/2016 +29 days 🔍
08/25/2016 +1 days 🔍
09/16/2016 +22 days 🔍
09/16/2016 +0 days 🔍
09/16/2016 +0 days 🔍
09/18/2016 +2 days 🔍
12/13/2016 +86 days 🔍
12/16/2016 +3 days 🔍
09/19/2022 +2103 days 🔍

Sourcesinfo

Product: openssl.org

Advisory: Bug 1370146
Researcher: Shi Lei
Status: Confirmed
Confirmation: 🔍
Coordinated: 🔍

CVE: CVE-2016-6303 (🔍)
OVAL: 🔍

SecurityTracker: 1036885
SecurityFocus: 92630 - SSL/TLS Protocol CVE-2016-2183 Information Disclosure Vulnerability

See also: 🔍

Entryinfo

Created: 09/18/2016 09:59
Updated: 09/19/2022 06:51
Changes: 09/18/2016 09:59 (80), 07/07/2019 16:16 (16), 09/19/2022 06:51 (4)
Complete: 🔍

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