[arch-security] [ASA-201503-14] ecryptfs-utils: hard-coded passphrase salt

[Levente Polyak]

Arch Linux Security Advisory ASA-201503-14
==========================================

Severity: Low
Date    : 2015-03-17
CVE-ID  : CVE-2014-9687
Package : ecryptfs-utils
Type    : hard-coded passphrase salt
Remote  : No
Link    : https://wiki.archlinux.org/index.php/CVE

Summary
=======

The package ecryptfs-utils before version 106-1 is vulnerable to
hard-coded passphrase salt that may ease a brute-force attack.

Resolution
==========

Upgrade to 106-1.

# pacman -Syu "ecryptfs-utils>=106-1"

The problem has been fixed upstream in version 106.

If pam_ecryptfs is used a transparent migration from version 1 to
version 2 files is provided, otherwise a manual re-wrapping of the
passphrase file is mandatory.

Workaround
==========

None.

Description
===========

eCryptfs uses a default salt to encrypt the mount passphrase, which
makes it easier for attackers to obtain user passwords via a brute force
attack. By default, the wrapping key is hashed with the default fixed
salt (0x0011223344556677).

This update introduces the version 2 wrapped-passphrase file format. It
adds the ability to combine a randomly generated salt with the wrapping
password (typically, a user's login password) prior to performing key
strengthening. The version 2 file format is considered to be a
intermediate step in strengthening the wrapped-passphrase files of
existing encrypted home/private users.

If pam_ecryptfs is used a transparent migration from version 1 to
version 2 files is provided, otherwise a manual re-wrapping of the
passphrase file is mandatory.

Impact
======

An attacker could use this issue to discover the login password used to
protect the mount passphrase and gain unintended access to the encrypted
files with the help of bulk dictionary attacks and rainbow tables to
crack user passwords.

References
==========

http://www.openwall.com/lists/oss-security/2015/02/10/10
https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-9687
https://bazaar.launchpad.net/~ecryptfs/ecryptfs/trunk/revision/839
https://bugs.archlinux.org/task/44157

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