OpenSSH up to 7.5 Readonly Mode sftp-server.c process_open permission

CVSS Meta Temp Score
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CTI Interest Score
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5.2$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as critical, has been found in OpenSSH up to 7.5. This affects the function process_open of the file sftp-server.c of the component Readonly Mode. Performing a manipulation results in permission. This vulnerability is reported as CVE-2017-15906. The attack is possible to be carried out remotely. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in OpenSSH up to 7.5 (Connectivity Software). It has been classified as critical. This affects the function process_open of the file sftp-server.c of the component Readonly Mode. The manipulation with an unknown input leads to a permission vulnerability. CWE is classifying the issue as CWE-275. This is going to have an impact on integrity. The summary by CVE is:

The process_open function in sftp-server.c in OpenSSH before 7.6 does not properly prevent write operations in readonly mode, which allows attackers to create zero-length files.

The bug was discovered 10/04/2017. The weakness was disclosed 10/26/2017 by Natalie Silvanovich with Microsoft Vulnerability Research (GitHub Repository). It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2017-15906 since 10/25/2017. 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 attack technique deployed by this issue is T1222 according to MITRE ATT&CK.

The vulnerability was handled as a non-public zero-day exploit for at least 21 days. During that time the estimated underground price was around $5k-$25k. The vulnerability scanner Nessus provides a plugin with the ID 104824 (Fedora 26 : openssh (2017-4862a3bfb1)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Fedora Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 197025 (Ubuntu Security Notification for Openssh Vulnerabilities (USN-3538-1)).

Upgrading to version 7.6 eliminates this vulnerability. A possible mitigation has been published 2 months after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Tenable (104824) and SecurityFocus (BID 84312†). The entries VDB-81325, VDB-81326, VDB-81327 and VDB-81328 are pretty similar. Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.3
VulDB Meta Temp Score: 5.2

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

NVD Base Score: 5.3
NVD Vector: 🔍

ADP CISA Base Score: 5.3
ADP CISA Vector: 🔍

CVSSv2info

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

NVD Base Score: 🔍

Exploitinginfo

Class: Permission
CWE: CWE-275 / CWE-266
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: 104824
Nessus Name: Fedora 26 : openssh (2017-4862a3bfb1)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

OpenVAS ID: 103247
OpenVAS Name: OpenSSH sftp-server Security Bypass Vulnerability (Windows)
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: OpenSSH 7.6
Patch: github.com

Timelineinfo

03/10/2016 🔍
10/04/2017 +573 days 🔍
10/25/2017 +21 days 🔍
10/25/2017 +0 days 🔍
10/26/2017 +1 days 🔍
10/26/2017 +0 days 🔍
11/28/2017 +33 days 🔍
11/29/2017 +1 days 🔍
05/29/2026 +3103 days 🔍

Sourcesinfo

Advisory: RHSA-2018:0980
Researcher: Natalie Silvanovich
Organization: Microsoft Vulnerability Research
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2017-15906 (🔍)
GCVE (CVE): GCVE-0-2017-15906
GCVE (VulDB): GCVE-100-108627

OVAL: 🔍

SecurityFocus: 84312 - Adobe Flash Player and AIR APSB16-08 Multiple Use After Free Remote Code Execution Vulnerabilities

See also: 🔍

Entryinfo

Created: 10/26/2017 09:28
Updated: 05/29/2026 03:57
Changes: 10/26/2017 09:28 (79), 11/30/2019 17:40 (7), 01/04/2023 14:42 (5), 05/29/2026 03:57 (28)
Complete: 🔍
Cache ID: 216::103

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