Ticket History #8282: SPNEGO and IAKERB context aliasing bugs [CVE-2015-2695][CVE-2015-2696]

Fix SPNEGO context aliasing bugs [CVE-2015-2695]

The SPNEGO mechanism currently replaces its context handle with the
mechanism context handle upon establishment, under the assumption that
most GSS functions are only called after context establishment. This
assumption is incorrect, and can lead to aliasing violations for some
programs. Maintain the SPNEGO context structure after context
establishment and refer to it in all GSS methods. Add initiate and
opened flags to the SPNEGO context structure for use in
gss_inquire_context() prior to context establishment.

CVE-2015-2695:

In MIT krb5 1.5 and later, applications which call
gss_inquire_context() on a partially-established SPNEGO context can
cause the GSS-API library to read from a pointer using the wrong type,
generally causing a process crash. This bug may go unnoticed, because
the most common SPNEGO authentication scenario establishes the context
after just one call to gss_accept_sec_context(). Java server
applications using the native JGSS provider are vulnerable to this
bug. A carefully crafted SPNEGO packet might allow the
gss_inquire_context() call to succeed with attacker-determined
results, but applications should not make access control decisions
based on gss_inquire_context() results prior to context establishment.

CVSSv2 Vector: AV:N/AC:M/Au:N/C:N/I:N/A:C/E:POC/RL:OF/RC:C

[ghudson@mit.edu: several bugfixes, style changes, and edge-case
behavior changes; commit message and CVE description]

(cherry picked from commit b51b33f2bc5d1497ddf5bd107f791c101695000d)
(cherry picked from commit 31fb730f1ad708f230e4387e02ed2f89b93c3607)

https://github.com/krb5/krb5/commit/1ff9a2ee449b194c48b8e40e329293a442e4c55c
Author: Nicolas Williams <nico@twosigma.com>
Committer: Tom Yu <tlyu@mit.edu>
Commit: 1ff9a2ee449b194c48b8e40e329293a442e4c55c
Branch: krb5-1.13
src/lib/gssapi/spnego/gssapiP_spnego.h | 2 +
src/lib/gssapi/spnego/spnego_mech.c | 254 ++++++++++++++++++++++++--------
2 files changed, 192 insertions(+), 64 deletions(-)

Fix IAKERB context aliasing bugs [CVE-2015-2696]

The IAKERB mechanism currently replaces its context handle with the
krb5 mechanism handle upon establishment, under the assumption that
most GSS functions are only called after context establishment. This
assumption is incorrect, and can lead to aliasing violations for some
programs. Maintain the IAKERB context structure after context
establishment and add new IAKERB entry points to refer to it with that
type. Add initiate and established flags to the IAKERB context
structure for use in gss_inquire_context() prior to context
establishment.

CVE-2015-2696:

In MIT krb5 1.9 and later, applications which call
gss_inquire_context() on a partially-established IAKERB context can
cause the GSS-API library to read from a pointer using the wrong type,
generally causing a process crash. Java server applications using the
native JGSS provider are vulnerable to this bug. A carefully crafted
IAKERB packet might allow the gss_inquire_context() call to succeed
with attacker-determined results, but applications should not make
access control decisions based on gss_inquire_context() results prior
to context establishment.

CVSSv2 Vector: AV:N/AC:M/Au:N/C:N/I:N/A:C/E:POC/RL:OF/RC:C

[ghudson@mit.edu: several bugfixes, style changes, and edge-case
behavior changes; commit message and CVE description]

(cherry picked from commit e04f0283516e80d2f93366e0d479d13c9b5c8c2a)
(cherry picked from commit 096cfaa18504d20889a3d8829decb1bf72dd0ac5)

https://github.com/krb5/krb5/commit/f84d3d246ef2960b2fedcbb5474b2b8a07b53be8
Author: Nicolas Williams <nico@twosigma.com>
Committer: Tom Yu <tlyu@mit.edu>
Commit: f84d3d246ef2960b2fedcbb5474b2b8a07b53be8
Branch: krb5-1.13
src/lib/gssapi/krb5/gssapiP_krb5.h | 114 ++++++++++++
src/lib/gssapi/krb5/gssapi_krb5.c | 105 ++++++++++--
src/lib/gssapi/krb5/iakerb.c | 351 +++++++++++++++++++++++++++++++++---
3 files changed, 529 insertions(+), 41 deletions(-)