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Gray Day: My Undercover Mission to Expose America's First Cyber Spy

4.14  ·  Rating details ·  295 ratings  ·  61 reviews
A cybersecurity expert and former FBI "ghost" tells the thrilling story of how he helped take down notorious FBI mole Robert Hanssen, the first Russian cyber spy.

Eric O'Neill was only twenty-six when he was tapped for the case of a lifetime: a one-on-one undercover investigation of the FBI's top target, a man suspected of spying for the Russians for nearly two decades
Hardcover, 304 pages
Published March 26th 2019 by Crown Publishing Group (NY)
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Eric O'Neill Hi John, thank you for the question! Yes, I go into the Brian Kelly investigation and the impact it had on Kelly's life as well as how the fact that…moreHi John, thank you for the question! Yes, I go into the Brian Kelly investigation and the impact it had on Kelly's life as well as how the fact that the FBI focused so heavily on Kelly helped Hanssen. I met Kelly months before he sadly passed away and we had a few illuminating discussions. (less)

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Mar 31, 2019 rated it really liked it  ·  review of another edition
I may deserve some of the epithets thrown at the young Eric O'Neill by his FBI boss because I do reluctantly admit to being a moron on this subject. What was it I was doing in 2001 to not know about Robert Hanssen who managed to stay hidden in the FBI whilst selling US security info to Russia for a period of 20 years?!
Let's see...the human genome sequence was revealed and my son had played a small role in that, there was a devastating earthquake in India, I lost a bunch of money and a job.
Randal White
The story of the takedown of Robert Hanssen, arguably one of the worst spies the United States has every had. Hanssen, a FBI employee, sold out to the Russians, giving them some of our most highly classified secrets for over twenty years. He was responsible for many deaths, and did untold damage to our national security.
The author was a young FBI "ghost", a person assigned to surveillance of people. He found himself placed in a position to work closely with Hanssen, trying to gain his trust, al
Shaun Breidbart
Mar 28, 2019 rated it it was amazing
Wow. What a story.
So stop reading the reviews and start reading the book!
Oct 06, 2019 rated it really liked it
This was a truly fascinating account of the hunt and capture of America’s first cyber spy Robert Hanson. The revelations of the main young agent in going undercover and having to keep secrets particularly from his German spouse made this a riveting story. The book ends with a somewhat preachy summation of the dangers posed by cyber spies and the failures of the US to account for this new danger but even so, it did raise my concerns and fears for maintaining the technology and innovation that mak ...more
Michelle Arredondo
Apr 02, 2019 rated it it was amazing
Great's hard to put down once you get started. Startling account of the mission to catch Robert Hanssen...the notorious spy that was selling secrets to the Russians. Not only to do we go on this timeline of events...this journey of intrigue but we also learn a lot from this book. We learn about the state of our world and how easy ( for the highly intelligent cyber junkies of the world) it can be to take secrets and reveal them in this age of internet. It's a powerful read full of anxie ...more
Sep 30, 2019 rated it it was amazing
Solid first person account, los of facts, just a dash of novelization, non-boring side stories and anectdotes and nice tie-off into events of the recent history. Can recommend.
Darren Sapp
Apr 05, 2019 rated it it was amazing
O'Neill has written a first-class memoir detailing his undercover mission to expose America's greatest traitor. Far from the Bond-like adventure we think of, the real work is gritty, sometimes boring, but also dangerous. It also has a tremendous impact on families. This is a spy story and a darn good one!
May 11, 2019 rated it did not like it
Lou Mallory
Mar 29, 2019 rated it it was amazing  ·  review of another edition
Excellent book about the Robert Hanssen case

I became interested in the Robert Hanssen case when I saw the film Breach a number of years ago. This book
Is written by Eric O'Neil who helped to bring Hanssen to justice. This is an exciting read--I could not put it down
and read it in two sittings. I admire O'Neill 's service and his honesty.
Mar 12, 2019 rated it it was amazing
Great book! Stayed up way too late reading it in one sitting. The psychological tension between O'Neill, the junior officer tasked to spy on his boss - the sketchy, irascible and magnificently traitorous master spy Robert Hanssen - is palpable. The mounting marital pressures and O'Neill's inability to talk about his work to his wife - or rather, the legal requirement to lie about it constantly - ratchets up the drama another notch. Why bother with Le Carré when you can read about the real thing? ...more
Zohar -
Apr 19, 2019 rated it it was amazing
Shelves: 2019
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Gray Day: My Undercover Mission to Expose America’s First Cyber Spy by Eric O’Neill is a non-fiction book following the author’s investigation into the FBI’s most damaging spy. Mr. O’Neill is a cybersecurity expert and a former FBI agent.

I have read many books about cybersecurity, and many books which spy Robert Hanssen (code name: Gray Day) is mentioned, but I never realized the two subject had anything to do with one another
Sep 22, 2019 rated it liked it
Shelves: read-2019
O'Neill's narrative of his role in the capture of Robert Hanssen is an interesting story that highlights the professionalism and and diligence of FBI agents and professionals working in the field. It would have been interesting if O'Neill had talked more about the important roles other individuals played in the investigation, but not doing so does not detract from his important role. One flaw of the book is how he ties his case to current cyber security challenges at various interludes in the bo ...more
J Earl
Apr 05, 2019 rated it liked it
Shelves: won, first-reads
Gray Day by Eric O'neill is an interesting book about early cyberspying. It is probably as interesting for nostalgia as it is for espionage.

This book and author just did not connect with me. I was left not particularly liking him (also not disliking him, just not liking either. As in, I would probably have not liked him had I known him) even while appreciating what he was having to do. That is obviously more about my personality than about the book, some people no doubt liked him tre
Apr 19, 2019 rated it really liked it
Part memoir, thriller and (gasp!) romance novel, this enjoyable read details the real-life actions of a young FBI employee in DC who delivered a knockout blow to a turncoat colleague who had shared critical American secrets with the Russians for decades. It was fun for me to read this behind-the-scenes drama about 2001 events I can recall as they unfolded in my then hometown. Having lived down the street from the Russian Embassy, in fact, and occasionally having encountered surveillance professi ...more
Greg Parrott
May 31, 2019 rated it liked it
Shelves: dcl-book
I attended a webinar where Eric O'Neill presented his story. I found his attitude and demeanor a bit cocky, but the underlying story was good. I decided to read the book as the book is almost always better than the "movie," right?

The usual cyber security pitfalls are included... social engineering or a disgruntled employee... Hanssen definitely was the disgruntled employee in the worst possible place. The story of the investigation was interesting along with the personal sacrifices t
Kevin Walsh
Apr 28, 2019 rated it liked it
Shelves: history, crime
Mixed feelings about this one. The good: Extremely interesting account of the author's involvement in helping bring down spy Robert Hanssen. The scenes involving the whole process are dramatic and exciting. I'm always amazed at the ingenuity and guts of people who work undercover. Bringing down Hanssen was a definite team effort, but the author had a key role and a front row seat which he shares well. The not-so-good: Some of the basic description in the setting of scenes felt a little over-the- ...more
Jun 11, 2019 rated it really liked it
The book covers the investigation of Robert Hanssen, an FBI agent turned spy for the Russians from the 80s until 2001. The setup feels like the setup of a Colombo story where the villain is introduced first and the rest of the story covers how the crime is solved.

Eric O’Neill has a good faced pace style that goes in to the investigative methods used, the complications faced by real investigators and being given a glimpse in to the world of hunting spies.

The author’s insig
Apr 26, 2019 rated it it was amazing
Shelves: espionage
Eric details his role in helping capturing the spy Robert Hanssen. Although his role was not a long one, it was crucial in obtaining the evidence that would lead to the capture and conviction (through plea) of the spy. We read about his personal and professional struggle that was required. This tale is also obviously the redacted version as it doesn't contain any extra details of what Hanssen stole or gave to the Russians/Soviets. It's amazing how long he was able to operate and give secrets awa ...more
Woodstock Pickett
A little slow going, about half way through the arc of the story picked up a little and I was reading with more dedication. Nevertheless, this is an intriguing story of how a criminal who learned how to exploit all sorts of weaknesses in the FBI's security measures and earned lots and lots and lots of money turning sensitive information over to the Soviets. O'Neill documents at least one case in which three Russian men living in the US and who had decided to work for the US, were recalled to Rus ...more
Jun 03, 2019 rated it really liked it
This review has been hidden because it contains spoilers. To view it, click here.
Jun 30, 2019 rated it really liked it
This book is suspenseful, astonishing, and informative. It is also discouraging in that it reveals the extent to which the US has trailed Russia, China, and a host of other malicious entities in the espionage and cybersecurity arenas. The book is well-written and rich with detail about the Robert Hannsen case and similar spy stories. Like many non-fiction authors, O'Neill is repetitive with certain material and there were many points when I felt he could have ended his narrative with impact. Asi ...more
Apr 01, 2019 rated it liked it
There is a gripping page-turner of a story in here, with chapters that end so skillfully that 'just one more' becomes an all-nighter. A whirlwind espionage tale of a relative newbie FBI agent, chosen largely because he would be the last guy suspected to go up against Robert Hanssen, the biggest mole the FBI ever had. The cat and mouse game ratchets up over the course of two tense, quick months.
Maybe the short time frame caused the editors to think about padding an otherwise-terse narrati
Apr 11, 2019 rated it it was amazing
This is a fascinating look at how the FBI tracked the most prolific cyber spy in their midst. Robert Hanssen had been operating successfully as a spy for Russia while holding top secret clearance in the FBI for more than two decades. The author was placed in a position to work directly for Hanssen while trying to obtain the necessary information to convict him. While they ultimately did, America paid a high price for his treason. This book is especially timely with what is going on in today's wo ...more
Jul 06, 2019 rated it really liked it
I enjoyed this book. I had read quite a bit about Robert Hanssen before reading this, but it was interesting to hear all the inside information from Eric O’Neill himself. I sometimes got bogged down in the cyber security details; even for someone who considers myself to be relatively tech savvy, it dragged a bit and those sections could have been paired down considerably.

Overall, it was definitely worth the read.
Nancy Thompson
Apr 14, 2019 rated it it was amazing
Shelves: 2019
I heard Eric O’Neil on the Spycast podcast and his interview was interesting. I thought I would buy the audio book as my non fiction read this week. He did not disappoint. I was at the edge of my seat several times throughout the book based on how the FBI sand CIA caught Robert Hansen. The most destructive and cruel spy in US history. I would recommend this book foot those who occasionally like spy thrillers.
Reneé Walters
Jul 13, 2019 rated it really liked it
Shelves: audiobook
When I first started listening to the audiobook, I realized I had already watched a movie about it... and I almost returned the audiobook. I'm glad I didn't! The book is written and narrated by the undercover agent, and I learned much more about the case and the FBI.... without the (unnecessary!) Hollywood spin. It was fascinating... worth a read or listen!
Jeanne Nichols
Mar 17, 2019 rated it really liked it
Shelves: giveaway
Robert Hanssen is the most harmful spy in American history and he got away with it for a very long time. This book explains part of the reason it took so long to catch him and part of the process by which he was caught.

I enjoyed this book, even though I felt that the author was giving himself a lot of the credit for Hanssen's apprehension. It was interesting, however.
Allen Stebbins
Apr 19, 2019 rated it really liked it
Robert Hansen did more damage to the United States than any other spy in history. This is the story of how the FBI caught him. At a time when the FBI is under unceasing attack by the current administration the professionalism of the Bureau comes through loud and clear, which personally I found very reassuring. The book is well, though not brilliantly, written and a worthwhile read.
Richard Dawkins
Oct 20, 2019 rated it really liked it
This book was really interesting. I liked how towards the end u really wondered what was going to happen. I do think the author dragged on in a few spots but for the most part it was an enjoyable read!
Sep 15, 2019 rated it really liked it
Interesting fun read with education on espionage and cyber security. I heard the author speak at Egnyte conference and received free copy of the book there. He is a good speaker, and even after hearing him there, I still found the book engrossing.
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Eric is an accomplished public speaker, security expert and author that presents keynotes internationally about espionage and national security, cybersecurity, fraud, corporate diligence and defense, hacking, pursuing ones dreams and surviving Hollywood.

Eric has worked as an FBI counterterrorism and counterintelligence operative, a national security attorney and as a corporate security
“There are no hackers, there are only spies. Hacking is nothing more than the natural evolution of espionage.” 2 likes
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