OpenSSL crypto/bn/bn_print.c BN_bn2dec t out-of-bounds write

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CVSS Meta Temp Score
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7.2$0-$5k0.04

A vulnerability classified as problematic was found in OpenSSL (Network Encryption Software) (affected version unknown). Affected by this vulnerability is the function BN_bn2dec of the file crypto/bn/bn_print.c. The manipulation of the argument t with an unknown input leads to a memory corruption vulnerability. The CWE definition for the vulnerability is CWE-787. As an impact it is known to affect availability.

The bug was discovered 08/25/2016. The weakness was disclosed 08/16/2016 by Shi Lei as USN-3087-1 as confirmed git commit (GIT Repository). The advisory is shared at git.openssl.org. The public release has been coordinated in cooperation with the project team. This vulnerability is known as CVE-2016-2182 since 01/29/2016. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/07/2019). Responsible for the vulnerability is the following code:

bn_data = OPENSSL_malloc((num / BN_DEC_NUM + 1) * sizeof(BN_ULONG));

The vulnerability scanner Nessus provides a plugin with the ID 95255 (AIX OpenSSL Advisory : openssl_advisory21.asc (SWEET32)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family AIX Local Security Checks and running in the context local. The commercial vulnerability scanner Qualys is able to test this issue with plugin 316384 (Cisco Unity Express OpenSSL Multiple Vulnerabilities (cisco-sa-20160927-openssl)).

Applying a patch is able to eliminate this problem. The bugfix is ready for download at git.openssl.org. A possible mitigation has been published immediately after the disclosure of the vulnerability. The vulnerability will be addressed with the following lines of code:

bn_data_num = num / BN_DEC_NUM + 1;
bn_data = OPENSSL_malloc(bn_data_num * sizeof(BN_ULONG));
The git commit contains the following remark:
Fix by checking return value of BN_div_word() and checking writes don't overflow buffer.

The vulnerability is also documented in the databases at SecurityFocus (BID 92557), SecurityTracker (ID 1036688) and Tenable (95255). The entries 87879, 88080, 90396 and 90939 are pretty similar.

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CPE 2.3infoedit

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CVSSv3infoedit

VulDB Meta Base Score: 7.5
VulDB Meta Temp Score: 7.2

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 9.8
NVD Vector: 🔍

CVSSv2infoedit

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

NVD Base Score: 🔍

Exploitinginfoedit

Class: Memory corruption
CWE: CWE-787
ATT&CK: Unknown

Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 95255
Nessus Name: AIX OpenSSL Advisory : openssl_advisory21.asc (SWEET32)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

OpenVAS ID: 59958
OpenVAS Name: RedHat Update for openssl RHSA-2016:1940-01
OpenVAS File: 🔍
OpenVAS Family: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

Threat Intelligenceinfoedit

Threat: 🔍
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Countermeasuresinfoedit

Recommended: Patch
Status: 🔍

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

Patch: git.openssl.org

Timelineinfoedit

01/29/2016 🔍
08/16/2016 +200 days 🔍
08/16/2016 +0 days 🔍
08/16/2016 +0 days 🔍
08/25/2016 +9 days 🔍
08/25/2016 +0 days 🔍
08/25/2016 +0 days 🔍
09/16/2016 +22 days 🔍
11/22/2016 +67 days 🔍
07/07/2019 +957 days 🔍

Sourcesinfoedit

Product: https://www.openssl.org/

Advisory: USN-3087-1
Researcher: Shi Lei
Status: Confirmed
Confirmation: 🔍
Coordinated: 🔍

CVE: CVE-2016-2182 (🔍)
OVAL: 🔍

SecurityFocus: 92557 - OpenSSL 'BN_bn2dec()' Function Out of Bounds Write Denial of Service Vulnerability
SecurityTracker: 1036688

See also: 🔍

Entryinfoedit

Created: 08/25/2016 11:29 AM
Updated: 07/07/2019 03:53 PM
Changes: (7) vulnerability_discoverydate vulnerability_cvss3_vuldb_ac vulnerability_cvss3_vuldb_pr advisory_confirm_url source_cve_assigned source_securityfocus_date source_securityfocus_class
Complete: 🔍

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