Exponent strongSwan up to up to 4.x/5.6. IKEv2 Authentication gmp_rsa_public_key.c verify_emsa_pkcs1_signature RSA Signature signature verification

CVSS Meta Temp Score
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CTI Interest Score
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6.4$0-$5k0.00

Summaryinfo

A vulnerability labeled as critical has been found in Exponent strongSwan up to up to 4.x/5.6.. This affects the function verify_emsa_pkcs1_signature of the file gmp_rsa_public_key.c of the component IKEv2 Authentication. Such manipulation as part of RSA Signature leads to signature verification. This vulnerability is traded as CVE-2018-16151. The attack may be launched remotely. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Exponent strongSwan up to up to 4.x/5.6. (Network Encryption Software) and classified as critical. Affected by this issue is the function verify_emsa_pkcs1_signature of the file gmp_rsa_public_key.c of the component IKEv2 Authentication. The manipulation as part of a RSA Signature leads to a signature verification vulnerability. Using CWE to declare the problem leads to CWE-347. The product does not verify, or incorrectly verifies, the cryptographic signature for data. Impacted is confidentiality, integrity, and availability. CVE summarizes:

In verify_emsa_pkcs1_signature() in gmp_rsa_public_key.c in the gmp plugin in strongSwan 4.x and 5.x before 5.7.0, the RSA implementation based on GMP does not reject excess data after the encoded algorithm OID during PKCS#1 v1.5 signature verification. Similar to the flaw in the same version of strongSwan regarding digestAlgorithm.parameters, a remote attacker can forge signatures when small public exponents are being used, which could lead to impersonation when only an RSA signature is used for IKEv2 authentication.

The bug was discovered 09/24/2018. The weakness was shared 09/26/2018 by Kevin Backhouse (Website). The advisory is shared for download at strongswan.org. This vulnerability is handled as CVE-2018-16151 since 08/29/2018. The exploitation is known to be difficult. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available.

The vulnerability was handled as a non-public zero-day exploit for at least 2 days. During that time the estimated underground price was around $0-$5k. The vulnerability scanner Nessus provides a plugin with the ID 117715 (Debian DLA-1522-1 : strongswan security update), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Debian Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 277550 (Fedora Security Update for strongswan (FEDORA-2018-9caa6528d2)).

Upgrading to version bis 4.x or 5.6.x eliminates this vulnerability. A possible mitigation has been published 2 hours after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Tenable (117715) and SecurityFocus (BID 104263†). The entries VDB-118481, VDB-119689 and VDB-124485 are related to this item. Once again VulDB remains the best source for vulnerability data.

Productinfo

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Version

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.5
VulDB Meta Temp Score: 6.4

VulDB Base Score: 5.6
VulDB Temp Score: 5.4
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 7.5
NVD Vector: 🔍

CVSSv2info

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

NVD Base Score: 🔍

Exploitinginfo

Class: Signature verification
CWE: CWE-347 / CWE-345
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: 117715
Nessus Name: Debian DLA-1522-1 : strongswan security update
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

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

Upgrade: strongSwan bis 4.x/5.6.x

Timelineinfo

05/23/2018 🔍
08/29/2018 +97 days 🔍
09/24/2018 +26 days 🔍
09/26/2018 +1 days 🔍
09/26/2018 +0 days 🔍
09/26/2018 +0 days 🔍
09/27/2018 +1 days 🔍
09/27/2018 +0 days 🔍
12/03/2025 +2624 days 🔍

Sourcesinfo

Advisory: USN-3771-1
Researcher: Kevin Backhouse
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2018-16151 (🔍)
GCVE (CVE): GCVE-0-2018-16151
GCVE (VulDB): GCVE-100-124484

OVAL: 🔍

SecurityFocus: 104263 - strongSwan CVE-2018-5388 Buffer Underflow Vulnerability

See also: 🔍

Entryinfo

Created: 09/27/2018 09:01
Updated: 12/03/2025 22:28
Changes: 09/27/2018 09:01 (79), 03/27/2020 09:32 (6), 05/19/2023 08:48 (4), 12/03/2025 22:28 (15)
Complete: 🔍
Cache ID: 216::103

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