Vulnerability Note VU#243585

SSL/TLS implementations accept export-grade RSA keys (FREAK attack)

Original Release date: 06 Mar 2015 | Last revised: 26 Oct 2015

Overview

Some implementations of SSL/TLS accept export-grade (512-bit or smaller) RSA keys even when not specifically requesting export grade ciphers. An attacker able to act as a Man-in-The-Middle (MiTM) could factor weak temporary RSA keys, obtain session keys, and decrypt SSL/TLS trafflc. This issue has been dubbed the "FREAK" (Factoring Attack on RSA-EXPORT Keys) attack.

Description

CWE-757: Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')

CWE-326: Inadequate Encryption Strength

Some implementations of SSL/TLS accept export-grade (512-bit or smaller) RSA keys even when not specifically requesting export grade ciphers. This can occur when a MiTM attacker asks for export grade ciphers on behalf of a client, and the client insecurely accepts the export grade key. The attacker can then factor the weak RSA key and use this key to decrypt other data necessary to generate the session key. The attacker can then decrypt data in the session.

The researchers provide a more detailed explanation on their website.

Impact

The weak 512-bit "export grade" RSA keys can be factored to allow an attacker to decrypt information encrypted with these keys.

Solution

Update SSL/TLS libraries and applications

Vendors are currently working on patches to address this issue. Affected users are advised to check with the software vendor and update as soon as possible. The Vendor Status information below provides more information for each vendor.

Do not offer export grade ciphers

Configure server and client applications not to use export grade ciphers (EC).

Vendor Information (Learn More)

VendorStatusDate NotifiedDate Updated
AppleAffected05 Mar 201506 Mar 2015
GoogleAffected05 Mar 201506 Mar 2015
Microsoft CorporationAffected05 Mar 201510 Mar 2015
NEC CorporationAffected-26 Oct 2015
OpenSSLAffected05 Mar 201506 Mar 2015
OperaAffected-06 Mar 2015
Research in Motion (RIM)Affected-06 Mar 2015
BotanNot Affected05 Mar 201506 Mar 2015
CryptlibNot Affected05 Mar 201509 Mar 2015
GnuTLSNot Affected05 Mar 201506 Mar 2015
IAIK Java GroupNot Affected05 Mar 201517 Mar 2015
Legion of the Bouncy CastleNot Affected05 Mar 201509 Mar 2015
Apache-SSLUnknown05 Mar 201505 Mar 2015
AttachmateUnknown05 Mar 201505 Mar 2015
CerticomUnknown05 Mar 201505 Mar 2015
If you are a vendor and your product is affected, let us know.View More »

CVSS Metrics (Learn More)

Group Score Vector
Base 7.8 AV:N/AC:L/Au:N/C:C/I:N/A:N
Temporal 6.4 E:F/RL:OF/RC:C
Environmental 6.4 CDP:ND/TD:H/CR:ND/IR:ND/AR:ND

References

Credit

This vulnerability was reported by researchers from INRIA, Microsoft Research, and IMDEA.

This document was written by Garret Wassermann.

Other Information

  • CVE IDs: Unknown
  • Date Public: 06 Mar 2015
  • Date First Published: 06 Mar 2015
  • Date Last Updated: 26 Oct 2015
  • Document Revision: 24

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