OpenVPN NTLM Version 2 Proxy ntlm.c ntlm_phase_3 certificate validation

CVSS Meta Temp Score
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CTI Interest Score
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6.1$0-$5k0.00

Summaryinfo

A vulnerability identified as problematic has been detected in OpenVPN. The affected element is the function ntlm_phase_3 of the file ntlm.c of the component NTLM Version 2 Proxy Handler. The manipulation leads to certificate validation. This vulnerability is listed as CVE-2017-7520. The attack may be initiated remotely. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in OpenVPN (Network Encryption Software) (affected version not known) and classified as problematic. This issue affects the function ntlm_phase_3 of the file ntlm.c of the component NTLM Version 2 Proxy Handler. The manipulation with an unknown input leads to a certificate validation vulnerability. Using CWE to declare the problem leads to CWE-295. The product does not validate, or incorrectly validates, a certificate. Impacted is confidentiality. The summary by CVE is:

OpenVPN versions before 2.4.3 and before 2.3.17 are vulnerable to denial-of-service and/or possibly sensitive memory leak triggered by man-in-the-middle attacker.

The bug was discovered 06/22/2017. The weakness was presented 06/21/2017 by Guido Vranken with https://guidovranken.wordpress.com as The OpenVPN post-audit bug bonanza as not defined blog post (Website). The advisory is shared at guidovranken.wordpress.com. The identification of this vulnerability is CVE-2017-7520 since 04/05/2017. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1587.003 for this issue. The following code is the reason for this vulnerability: 

if (( *((long *)&buf2[0x14]) & 0x00800000) == 0x00800000)          /* Check for Target Information block */
{
    tib_len = buf2[0x28];            /* Get Target Information block size */
    if (tib_len > 96)
    {
        tib_len = 96;
    }
    {
        char *tib_ptr = buf2 + buf2[0x2c];           /* Get Target Information block pointer */
        memcpy(&ntlmv2_blob[0x1c], tib_ptr, tib_len);           /* Copy Target Information block into the blob */
    }
}

The vulnerability scanner Nessus provides a plugin with the ID 101064 (Amazon Linux AMI : openvpn (ALAS-2017-852)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Amazon Linux Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 196832 (Ubuntu Security Notification for Openvpn Vulnerabilities (USN-3339-1)).

Upgrading eliminates this vulnerability. The upgrade is hosted for download at openvpn.net. A possible mitigation has been published 6 days after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Tenable (101064) and SecurityFocus (BID 99230†). See VDB-102707, VDB-102708, VDB-102709 and VDB-102710 for similar entries. Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

Name

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.3
VulDB Meta Temp Score: 6.2

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

NVD Base Score: 7.4
NVD Vector: 🔍

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Certificate validation
CWE: CWE-295 / CWE-287
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 101064
Nessus Name: Amazon Linux AMI : openvpn (ALAS-2017-852)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

OpenVAS ID: 703900
OpenVAS Name: Debian Security Advisory DSA 3900-1 (openvpn - security update)
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: openvpn.net

Timelineinfo

04/05/2017 🔍
06/21/2017 +77 days 🔍
06/21/2017 +0 days 🔍
06/22/2017 +1 days 🔍
06/22/2017 +0 days 🔍
06/27/2017 +5 days 🔍
06/27/2017 +0 days 🔍
06/28/2017 +1 days 🔍
12/29/2020 +1280 days 🔍

Sourcesinfo

Advisory: The OpenVPN post-audit bug bonanza
Researcher: Guido Vranken
Organization: https://guidovranken.wordpress.com
Status: Not defined
Confirmation: 🔍

CVE: CVE-2017-7520 (🔍)
GCVE (CVE): GCVE-0-2017-7520
GCVE (VulDB): GCVE-100-102713

OVAL: 🔍

SecurityFocus: 99230 - OpenVPN Multiple Security Vulnerabilities
SecurityTracker: 1038768

See also: 🔍

Entryinfo

Created: 06/21/2017 17:48
Updated: 12/29/2020 11:28
Changes: 06/21/2017 17:48 (82), 10/19/2019 14:23 (6), 12/29/2020 11:28 (3)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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