TLS Protocol up to 1.2 DHE_EXPORT Ciphersuite Logjam cryptographic issues

CVSS Meta Temp Score
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CTI Interest Score
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3.5$0-$5k0.13

A vulnerability has been found in TLS Protocol up to 1.2 and classified as critical. This vulnerability affects an unknown functionality of the component DHE_EXPORT Ciphersuite. The manipulation with an unknown input leads to a cryptographic issues vulnerability (Logjam). The CWE definition for the vulnerability is CWE-310. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

The TLS protocol 1.2 and earlier, when a DHE_EXPORT ciphersuite is enabled on a server but not on a client, does not properly convey a DHE_EXPORT choice, which allows man-in-the-middle attackers to conduct cipher-downgrade attacks by rewriting a ClientHello with DHE replaced by DHE_EXPORT and then rewriting a ServerHello with DHE_EXPORT replaced by DHE, aka the "Logjam" issue.

The weakness was released 05/21/2015 by David Adrian, Karthikeyan Bhargavan, Zakir Durumeric, Pierrick Gaudry, Matthew Green, J. Alex Halderman, Nadia Heninger, Drew Springall, Emmanuel Thomé, Luke Valenta, Benjamin VanderSloot, Eric Wustrow, Santiago Zanella-Béguelink and Paul Zimmermann as FG-IR-15-013 / CTX201114 as confirmed mailinglist post (oss-sec). The advisory is shared for download at seclists.org. This vulnerability was named CVE-2015-4000 since 05/15/2015. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 05/19/2022). The MITRE ATT&CK project declares the attack technique as T1600. This vulnerability has a historic impact due to its background and reception.

As 0-day the estimated underground price was around $25k-$100k. The vulnerability scanner Nessus provides a plugin with the ID 83937 (Fedora 21 : nss-3.19.1-1.0.fc21 / nss-softokn-3.19.1-1.0.fc21 / nss-util-3.19.1-1.0.fc21 (2015-9130) (Logjam)), 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 Nessus plugin is testing the existence of the vulnerability with the following NASL code:

if (rpm_check(release:"ALA", reference:"openssl-1.0.1k-10.86.amzn1")) flag++;
if (rpm_check(release:"ALA", reference:"openssl-debuginfo-1.0.1k-10.86.amzn1")) flag++;
if (rpm_check(release:"ALA", reference:"openssl-devel-1.0.1k-10.86.amzn1")) flag++;
if (rpm_check(release:"ALA", reference:"openssl-perl-1.0.1k-10.86.amzn1")) flag++;
if (rpm_check(release:"ALA", reference:"openssl-static-1.0.1k-10.86.amzn1")) flag++;

if (flag)
{
  if (report_verbosity > 0) security_hole(port:0, extra:rpm_report_get());
  else security_hole(0);
  exit(0);
}
The commercial vulnerability scanner Qualys is able to test this issue with plugin 350152 (Amazon Linux Security Advisory for openssl: ALAS-2015-550).

It is possible to mitigate the problem by applying the configuration setting . A possible mitigation has been published 2 weeks after the disclosure of the vulnerability. The mailinglist post contains the following remark:

We have three recommendations for correctly deploying Diffie-Hellman for TLS: 1. Disable Export Cipher Suites, 2. Deploy (Ephemeral) Elliptic-Curve Diffie-Hellman (ECDHE), 3. Generate a Strong, Unique Diffie Hellman Group.
Furthermore it is possible to detect and prevent this kind of attack with TippingPoint and the filter 19886.

The vulnerability is also documented in the databases at X-Force (103294) and Tenable (83937). Additional details are provided at weakdh.org. Entries connected to this vulnerability are available at 75951, 78627, 78668 and 80581.

Affected

  • Debian GNU/Linux

Productinfo

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Version

CPE 2.3info

CPE 2.2info

Screenshot

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CVSSv4info

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CVSSv3info

VulDB Meta Base Score: 3.7
VulDB Meta Temp Score: 3.5

VulDB Base Score: 3.7
VulDB Temp Score: 3.3
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 3.7
NVD Vector: 🔍

CVSSv2info

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VulDB Base Score: 🔍
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Exploitinginfo

Name: Logjam
Class: Cryptographic issues / Logjam
CWE: CWE-310
CAPEC: 🔍
ATT&CK: 🔍

Local: No
Remote: Yes

Availability: 🔍
Status: Unproven

EPSS Score: 🔍
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Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 83937
Nessus Name: Fedora 21 : nss-3.19.1-1.0.fc21 / nss-softokn-3.19.1-1.0.fc21 / nss-util-3.19.1-1.0.fc21 (2015-9130) (Logjam)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍
Nessus Port: 🔍

OpenVAS ID: 14611
OpenVAS Name: Amazon Linux Local Check: alas-2015-586
OpenVAS File: 🔍
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Qualys ID: 🔍
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Threat Intelligenceinfo

Interest: 🔍
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Countermeasuresinfo

Recommended: Config
Status: 🔍

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TippingPoint: 🔍

McAfee IPS: 🔍
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Fortigate IPS: 🔍

Timelineinfo

05/15/2015 🔍
05/19/2015 +4 days 🔍
05/20/2015 +1 days 🔍
05/21/2015 +1 days 🔍
05/21/2015 +0 days 🔍
05/30/2015 +9 days 🔍
06/02/2015 +3 days 🔍
07/08/2015 +36 days 🔍
08/02/2015 +25 days 🔍
05/19/2022 +2482 days 🔍

Sourcesinfo

Advisory: FG-IR-15-013 / CTX201114
Researcher: David Adrian, Karthikeyan Bhargavan, Zakir Durumeric, Pierrick Gaudry, Matthew Green, J. Alex Halderman, Nadia Heninger, Drew Springall, Emmanuel Thomé, Luke Valenta, Benjamin VanderSloot, Eric Wustrow, Santiago Zanella-Béguelink, Paul Zimmermann
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2015-4000 (🔍)
OVAL: 🔍

X-Force: 103294 - TLS Diffie-Hellman Key Exchange information disclosure
SecurityTracker: 1032474
Vulnerability Center: 51701 - TLS <=1.2 Remote Man-in-the Middle via Cipher-Downgrade Attacks (aka \, Medium
SecurityFocus: 74733 - SSL/TLS LogJam Man in the Middle Security Bypass Vulnerability
OSVDB: 122331

Misc.: 🔍
See also: 🔍

Entryinfo

Created: 05/21/2015 10:17
Updated: 05/19/2022 09:19
Changes: 05/21/2015 10:17 (89), 05/03/2019 21:38 (15), 05/19/2022 09:19 (4)
Complete: 🔍
Cache ID: 3:8C7:103

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