9 research outputs found
Characterizing Phishing Threats with Natural Language Processing
Spear phishing is a widespread concern in the modern network security
landscape, but there are few metrics that measure the extent to which
reconnaissance is performed on phishing targets. Spear phishing emails closely
match the expectations of the recipient, based on details of their experiences
and interests, making them a popular propagation vector for harmful malware. In
this work we use Natural Language Processing techniques to investigate a
specific real-world phishing campaign and quantify attributes that indicate a
targeted spear phishing attack. Our phishing campaign data sample comprises 596
emails - all containing a web bug and a Curriculum Vitae (CV) PDF attachment -
sent to our institution by a foreign IP space. The campaign was found to
exclusively target specific demographics within our institution. Performing a
semantic similarity analysis between the senders' CV attachments and the
recipients' LinkedIn profiles, we conclude with high statistical certainty (p
) that the attachments contain targeted rather than randomly
selected material. Latent Semantic Analysis further demonstrates that
individuals who were a primary focus of the campaign received CVs that are
highly topically clustered. These findings differentiate this campaign from one
that leverages random spam.Comment: This paper has been accepted for publication by the IEEE Conference
on Communications and Network Security in September 2015 at Florence, Italy.
Copyright may be transferred without notice, after which this version may no
longer be accessibl
A Study of the Shortest-Period Planets Found With Kepler
We present the results of a survey aimed at discovering and studying
transiting planets with orbital periods shorter than one day
(ultra--short-period, or USP, planets), using data from the {\em Kepler}
spacecraft. We computed Fourier transforms of the photometric time series for
all 200,000 target stars, and detected transit signals based on the presence of
regularly spaced sharp peaks in the Fourier spectrum. We present a list of 106
USP candidates, of which 18 have not previously been described in the
literature. In addition, among the objects we studied, there are 26 USP
candidates that had been previously reported in the literature which do not
pass our various tests. All 106 of our candidates have passed several standard
tests to rule out false positives due to eclipsing stellar systems. A low false
positive rate is also implied by the relatively high fraction of candidates for
which more than one transiting planet signal was detected. By assuming these
multi-transit candidates represent coplanar multi-planet systems, we are able
to infer that the USP planets are typically accompanied by other planets with
periods in the range 1-50 days, in contrast with hot Jupiters which very rarely
have companions in that same period range. Another clear pattern is that almost
all USP planets are smaller than 2 , possibly because gas giants in
very tight orbits would lose their atmospheres by photoevaporation when subject
to extremely strong stellar irradiation. Based on our survey statistics, USP
planets exist around approximately of G-dwarf stars, and
of K-dwarf stars.Comment: 20 pages, 10 figures. Submitted to ApJ. This version has been
reviewed by a refere
Transits and Occultations of an Earth-Sized Planet in an 8.5-Hour Orbit
We report the discovery of an Earth-sized planet () in
an 8.5-hour orbit around a late G-type star (KIC 8435766, Kepler-78). The
object was identified in a search for short-period planets in the {\it Kepler}
database and confirmed to be a transiting planet (as opposed to an eclipsing
stellar system) through the absence of ellipsoidal light variations or
substantial radial-velocity variations. The unusually short orbital period and
the relative brightness of the host star ( = 11.5) enable robust
detections of the changing illumination of the visible hemisphere of the
planet, as well as the occultations of the planet by the star. We interpret
these signals as representing a combination of reflected and reprocessed light,
with the highest planet dayside temperature in the range of 2300 K to 3100 K.
Follow-up spectroscopy combined with finer sampling photometric observations
will further pin down the system parameters and may even yield the mass of the
planet.Comment: Accepted for publication, ApJ, 10 pages and 6 figure
Brown Dwarfs in Young Moving Groups from Pan-STARRS1. I. AB Doradus
Substellar members of young (150 Myr) moving groups are valuable
benchmarks to empirically define brown dwarf evolution with age and to study
the low-mass end of the initial mass function. We have combined Pan-STARRS1
(PS1) proper motions with opticalIR photometry from PS1, 2MASS and
to search for substellar members of the AB Dor Moving Group
within 50 pc and with spectral types of late-M to early-L,
corresponding to masses down to 30 M at the age of the group
(125 Myr). Including both photometry and proper motions allows us to
better select candidates by excluding field dwarfs whose colors are similar to
young AB~Dor Moving Group members. Our near-IR spectroscopy has identified six
ultracool dwarfs (M6L4; 30100 M) with intermediate
surface gravities (INT-G) as candidate members of the AB Dor Moving Group. We
find another two candidate members with spectra showing hints of youth but
consistent with field gravities. We also find four field brown dwarfs
unassociated with the AB Dor Moving Group, three of which have INT-G gravity
classification. While signatures of youth are present in the spectra of our
125 Myr objects, neither their nor colors are
significantly redder than field dwarfs with the same spectral types, unlike
younger ultracool dwarfs. We also determined PS1 parallaxes for eight of our
candidates and one previously identified AB Dor Moving Group candidate.
Although radial velocities (and parallaxes, for some) are still needed to fully
assess membership, these new objects provide valuable insight into the spectral
characteristics and evolution of young brown dwarfs.Comment: ApJ, accepte
Planets Around Low-Mass Stars (PALMS). V. Age-Dating Low-Mass Companions to Members and Interlopers of Young Moving Groups
Copyright © 2015. The American Astronomical Society. All rights reserved.We present optical and near-infrared adaptive optics (AO) imaging and spectroscopy of 13 ultracool (>M6) companions to late-type stars (K7-M4.5), most of which have recently been identified as candidate members of nearby young moving groups (YMGs; 8-120 Myr) in the literature. The inferred masses of the companions (~10-100 Mjup) are highly sensitive to the ages of the primary stars so we critically examine the kinematic and spectroscopic properties of each system to distinguish bona fide YMG members from old field interlopers. 2MASS J02155892-0929121 C is a new M7 substellar companion (40-60 Mjup) with clear spectroscopic signs of low gravity and hence youth. The primary, possibly a member of the ~40 Myr Tuc-Hor moving group, is visually resolved into three components, making it a young low-mass quadruple system in a compact (1 Gyr) tidally-locked spectroscopic binaries without convincing kinematic associations with any known moving group. The high rate of false positives in the form of old active stars with YMG-like kinematics underscores the importance of radial velocity and parallax measurements to validate candidate young stars identified via proper motion and activity selection alone. Finally, we spectroscopically confirm the cool temperature and substellar nature of HD 23514 B, a recently discovered M8 benchmark brown dwarf orbiting the dustiest-known member of the Pleiades.NASANSFMt. Cuba Astronomical FoundationSamuel OschinAlfred P. Sloan Foundatio