[ GLSA 200609-15 ] GnuTLS: RSA Signature Forgery

[GLSA]

Gentoo Linux Security Advisory

Title: GnuTLS: RSA Signature Forgery (GLSA 200609-15)
Severity: normal
Exploitable: remote
Date: September 26, 2006
Bug(s): #147682
ID: 200609-15

Synopsis


GnuTLS fails to handle excess data which could allow an attacker to forge a
PKCS #1 v1.5 signature.


Background


GnuTLS is an implementation of SSL 3.0 and TLS 1.0.


Affected Packages

Package: net-libs/gnutls
Vulnerable: < 1.4.4
Unaffected: >= 1.4.4
Architectures: All supported architectures


Description


verify.c fails to properly handle excess data in
digestAlgorithm.parameters field while generating a hash when using an
RSA key with exponent 3. RSA keys that use exponent 3 are commonplace.


Impact


Remote attackers could forge PKCS #1 v1.5 signatures that are signed
with an RSA key, preventing GnuTLS from correctly verifying X.509 and
other certificates that use PKCS.


Workaround


There is no known workaround at this time.


Resolution


All GnuTLS users should update both packages: