Crypt::CBC: Insecure initialization vector

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200603-15 / crypt-cbc
Release Date	March 17, 2006
Latest Revision	March 17, 2006: 01
Impact	low
Exploitable	remote

Package	Vulnerable versions	Unaffected versions	Architecture(s)
dev-perl/crypt-cbc	< 2.17	>= 2.17	All supported architectures

Related bugreports: #126048

Synopsis

Crypt::CBC uses an insecure initialization vector, potentially resulting in a weaker encryption.

2. Impact Information

Background

Crypt::CBC is a Perl module to encrypt data using cipher block chaining (CBC).

Description

Lincoln Stein discovered that Crypt::CBC fails to handle 16 bytes long initializiation vectors correctly when running in the RandomIV mode, resulting in a weaker encryption because the second part of every block will always be encrypted with zeros if the blocksize of the cipher is greater than 8 bytes.

Impact

An attacker could exploit weak ciphertext produced by Crypt::CBC to bypass certain security restrictions or to gain access to sensitive data.

3. Resolution Information

Workaround

There is no known workaround at this time.

Resolution

All Crypt::CBC users should upgrade to the latest available version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=dev-perl/crypt-cbc-2.17"

4. References

CVE-2006-0898

Page updated March 17, 2006

Summary: This is a Gentoo Linux Security Advisory

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