Category Archives: identity theft

Episode 258: Broken Brokers – Optery’s Fight To Claw Back Your Personal Data

Lawrence Gentilello, the co-founder and CEO of Optery talks about the growing scandal around breaches at data brokers that have exposed the sensitive data on hundreds of millions of Americans to cyber criminals and how firms like Optery are helping people fight back.

The post Episode 258: Broken Brokers – Optery’s Fight To Claw Back Your Personal Data appeared first on The Security Ledger with Paul F. Roberts.

Smashing Security podcast #370: The closed loop conundrum, default passwords, and Baby Reindeer

The UK Government takes aim at IoT devices shipping with weak or default passwords, an identity thief spends two years in jail after being mistaken for the person who stole his name, and are you au fait with the latest scams?All this and much more is discussed in the latest edition of the “Smashing Security” podcast by cybersecurity veterans Graham Cluley and Carole Theriault, joined this week by Paul Ducklin.

It’s Still Easy for Anyone to Become You at Experian

In the summer of 2022, KrebsOnSecurity documented the plight of several readers who had their accounts at big-three consumer credit reporting bureau Experian hijacked after identity thieves simply re-registered the accounts using a different email address. Sixteen months later, Experian clearly has not addressed this gaping lack of security. I know that because my account at Experian was recently hacked, and the only way I could recover access was by recreating the account.

Entering my SSN and birthday at Experian showed my identity was tied to an email address I did not authorize.

I recently ordered a copy of my credit file from Experian via annualcreditreport.com, but as usual Experian declined to provide it, saying they couldn’t verify my identity. Attempts to log in to my account directly at Experian.com also failed; the site said it didn’t recognize my username and/or password.

A request for my Experian account username required my full Social Security number and date of birth, after which the website displayed portions of an email address I never authorized and did not recognize (the full address was redacted by Experian).

I immediately suspected that Experian was still allowing anyone to recreate their credit file account using the same personal information but a different email address, a major authentication failure that was explored in last year’s story, Experian, You Have Some Explaining to Do. So once again I sought to re-register as myself at Experian.

The homepage said I needed to provide a Social Security number and mobile phone number, and that I’d soon receive a link that I should click to verify myself. The site claims that the phone number you provide will be used to help validate your identity. But it appears you could supply any phone number in the United States at this stage in the process, and Experian’s website would not balk. Regardless, users can simply skip this step by selecting the option to “Continue another way.”

Experian then asks for your full name, address, date of birth, Social Security number, email address and chosen password. After that, they require you to successfully answer between three to five multiple-choice security questions whose answers are very often based on public records. When I recreated my account this week, only two of the five questions pertained to my real information, and both of those questions concerned street addresses we’ve previously lived at — information that is just a Google search away.

Assuming you sail through the multiple-choice questions, you’re prompted to create a 4-digit PIN and provide an answer to one of several pre-selected challenge questions. After that, your new account is created and you’re directed to the Experian dashboard, which allows you to view your full credit file, and freeze or unfreeze it.

At this point, Experian will send a message to the old email address tied to the account, saying certain aspects of the user profile have changed. But this message isn’t a request seeking verification: It’s just a notification from Experian that the account’s user data has changed, and the original user is offered zero recourse here other than to a click a link to log in at Experian.com.

If you don’t have an Experian account, it’s a good idea to create one. Because at least then you will receive one of these  emails when someone hijacks your credit file at Experian.

And of course, a user who receives one of these notices will find that the credentials to their Experian account no longer work. Nor do their PIN or account recovery question, because those have been changed also. Your only option at this point is recreate your account at Experian and steal it back from the ID thieves!

In contrast, if you try to modify an existing account at either of the other two major consumer credit reporting bureaus — Equifax or TransUnion — they will ask you to enter a code sent to the email address or phone number on file before any changes can be made.

Reached for comment, Experian declined to share the full email address that was added without authorization to my credit file.

“To ensure the protection of consumers’ identities and information, we have implemented a multi-layered security approach, which includes passive and active measures, and are constantly evolving,” Experian spokesperson Scott Anderson said in an emailed statement. “This includes knowledge-based questions and answers, and device possession and ownership verification processes.”

Anderson said all consumers have the option to activate a multi-factor authentication method that’s requested each time they log in to their account. But what good is multi-factor authentication if someone can simply recreate your account with a new phone number and email address?

Several readers who spotted my rant about Experian on Mastodon earlier this week responded to a request to validate my findings. The Mastodon user @Jackerbee is a reader from Michican who works in the biotechnology industry. @Jackerbee said when prompted by Experian to provide his phone number and the last four digits of his SSN, he chose the option to “manually enter my information.”

“I put my second phone number and the new email address,” he explained. “I received a single email in my original account inbox that said they’ve updated my information after I ‘signed up.’ No verification required from the original email address at any point. I also did not receive any text alerts at the original phone number. The especially interesting and egregious part is that when I sign in, it does 2FA with the new phone number.”

The Mastodon user PeteMayo said they recreated their Experian account twice this week, the second time by supplying a random landline number.

“The only difference: it asked me FIVE questions about my personal history (last time it only asked three) before proclaiming, ‘Welcome back, Pete!,’ and granting full access,” @PeteMayo wrote. “I feel silly saving my password for Experian; may as well just make a new account every time.”

I was fortunate in that whoever hijacked my account did not also thaw my credit freeze.  Or if they did, they politely froze it again when they were done. But I fully expect my Experian account will be hijacked yet again unless Experian makes some important changes to its authentication process.

It boggles the mind that these fundamental authentication weaknesses have been allowed to persist for so long at Experian, which already has a horrible track record in this regard.

In December 2022, KrebsOnSecurity alerted Experian that identity thieves had worked out a remarkably simple way to bypass its security and access any consumer’s full credit report — armed with nothing more than a person’s name, address, date of birth, and Social Security number. Experian fixed the glitch, and acknowledged that it persisted for nearly seven weeks, between Nov. 9, 2022 and Dec. 26, 2022.

In April 2021, KrebsOnSecurity revealed how identity thieves were exploiting lax authentication on Experian’s PIN retrieval page to unfreeze consumer credit files. In those cases, Experian failed to send any notice via email when a freeze PIN was retrieved, nor did it require the PIN to be sent to an email address already associated with the consumer’s account.

A few days after that April 2021 story, KrebsOnSecurity broke the news that an Experian API was exposing the credit scores of most Americans.

More greatest hits from Experian:

2022: Class Action Targets Experian Over Account Security
2017: Experian Site Can Give Anyone Your Credit Freeze PIN
2015: Experian Breach Affects 15 Million Customers
2015: Experian Breach Tied to NY-NJ ID Theft Ring
2015: At Experian, Security Attrition Amid Acquisitions
2015: Experian Hit With Class Action Over ID Theft Service
2014: Experian Lapse Allowed ID Theft Service Access to 200 Million Consumer Records
2013: Experian Sold Consumer Data to ID Theft Service

Smashing Security podcast #322: When you buy a criminal’s phone, and paying for social media scams

Personal information is going for a song, and the banks want social media sites to pay when their users get scammed.All this and much more is discussed in the latest edition of the "Smashing Security" podcast by computer security veterans Graham Cluley and Carole Theriault.

Confessions of an ID Theft Kingpin, Part II

Yesterday’s piece told the tale of Hieu Minh Ngo, a hacker the U.S. Secret Service described as someone who caused more material financial harm to more Americans than any other convicted cybercriminal. Ngo was recently deported back to his home country after serving more than seven years in prison for running multiple identity theft services. He now says he wants to use his experience to convince other cybercriminals to use their skills for good. Here’s a look at what happened after he got busted.

Hieu Minh Ngo, 29, in a recent photo.

Part I of this series ended with Ngo in handcuffs after disembarking a flight from his native Vietnam to Guam, where he believed he was going to meet another cybercriminal who’d promised to hook him up with the mother of all consumer data caches.

Ngo had been making more than $125,000 a month reselling ill-gotten access to some of the biggest data brokers on the planet. But the Secret Service discovered his various accounts at these data brokers and had them shut down one by one. Ngo became obsessed with restarting his business and maintaining his previous income. By this time, his ID theft services had earned roughly USD $3 million.

As this was going on, Secret Service agents used an intermediary to trick Ngo into thinking he’d trodden on the turf of another cybercriminal. From Part I:

The Secret Service contacted Ngo through an intermediary in the United Kingdom — a known, convicted cybercriminal who agreed to play along. The U.K.-based collaborator told Ngo he had personally shut down Ngo’s access to Experian because he had been there first and Ngo was interfering with his business.

“The U.K. guy told Ngo, ‘Hey, you’re treading on my turf, and I decided to lock you out. But as long as you’re paying a vig through me, your access won’t go away’,” the Secret Service’s Matt O’Neill recalled.

After several months of conversing with his apparent U.K.-based tormentor, Ngo agreed to meet him in Guam to finalize the deal. But immediately after stepping off of the plane in Guam, he was apprehended by Secret Service agents.

“One of the names of his identity theft services was findget[.]me,” O’Neill said. “We took that seriously, and we did like he asked.”

In an interview with KrebsOnSecurity, Ngo said he spent about two months in a Guam jail awaiting transfer to the United States. A month passed before he was allowed a 10 minute phone call to his family and explain what he’d gotten himself into.

“This was a very tough time,” Ngo said. “They were so sad and they were crying a lot.”

First stop on his prosecution tour was New Jersey, where he ultimately pleaded guilty to hacking into MicroBilt, the first of several data brokers whose consumer databases would power different iterations of his identity theft service over the years.

Next came New Hampshire, where another guilty plea forced him to testify in three different trials against identity thieves who had used his services for years. Among them was Lance Ealy, a serial ID thief from Dayton, Ohio who used Ngo’s service to purchase more than 350 “fullz” — a term used to describe a package of everything one would need to steal someone’s identity, including their Social Security number, mother’s maiden name, birth date, address, phone number, email address, bank account information and passwords.

Ealy used Ngo’s service primarily to conduct tax refund fraud with the U.S. Internal Revenue Service (IRS), claiming huge refunds in the names of ID theft victims who first learned of the fraud when they went to file their taxes and found someone else had beat them to it.

Ngo’s cooperation with the government ultimately led to 20 arrests, with a dozen of those defendants lured into the open by O’Neill and other Secret Service agents posing as Ngo.

The Secret Service had difficulty pinning down the exact amount of financial damage inflicted by Ngo’s various ID theft services over the years, primarily because those services only kept records of what customers searched for — not which records they purchased.

But based on the records they did have, the government estimated that Ngo’s service enabled approximately $1.1 billion in new account fraud at banks and retailers throughout the United States, and roughly $64 million in tax refund fraud with the states and the IRS.

“We interviewed a number of Ngo’s customers, who were pretty open about why they were using his services,” O’Neill said. “Many of them told us the same thing: Buying identities was so much better for them than stolen payment card data, because card data could be used once or twice before it was no good to them anymore. But identities could be used over and over again for years.”

O’Neill said he still marvels at the fact that Ngo’s name is practically unknown when compared to the world’s most infamous credit card thieves, some of whom were responsible for stealing hundreds of millions of cards from big box retail merchants.

“I don’t know of anyone who has come close to causing more material harm than Ngo did to the average American,” O’Neill said. “But most people have probably never heard of him.”

Ngo said he wasn’t surprised that his services were responsible for so much financial damage. But he was utterly unprepared to hear about the human toll. Throughout the court proceedings, Ngo sat through story after dreadful story of how his work had ruined the financial lives of people harmed by his services.

“When I was running the service, I didn’t really care because I didn’t know my customers and I didn’t know much about what they were doing with it,” Ngo said. “But during my case, the federal court received like 13,000 letters from victims who complained they lost their houses, jobs, or could no longer afford to buy a home or maintain their financial life because of me. That made me feel really bad, and I realized I’d been a terrible person.”

Even as he bounced from one federal detention facility to the next, Ngo always seemed to encounter ID theft victims wherever he went, including prison guards, healthcare workers and counselors.

“When I was in jail at Beaumont, Texas I talked to one of the correctional officers there who shared with me a story about her friend who lost her identity and then lost everything after that,” Ngo recalled. “Her whole life fell apart. I don’t know if that lady was one of my victims, but that story made me feel sick. I know now that was I was doing was just evil.”

Ngo’s former ID theft service usearching[.]info.


The Vietnamese hacker was released from prison a few months ago, and is now finishing up a mandatory three-week COVID-19 quarantine in a government-run facility near Ho Chi Minh city. In the final months of his detention, Ngo started reading everything he could get his hands on about computer and Internet security, and even authored a lengthy guide written for the average Internet user with advice about how to avoid getting hacked or becoming the victim of identity theft.

Ngo said while he would like to one day get a job working in some cybersecurity role, he’s in no hurry to do so. He’s already had at least one job offer in Vietnam, but he turned it down. He says he’s not ready to work yet, but is looking forward to spending time with his family — and specifically with his dad, who was recently diagnosed with Stage 4 cancer.

Longer term, Ngo says, he wants to mentor young people and help guide them on the right path, and away from cybercrime. He’s been brutally honest about his crimes and the destruction he’s caused. His LinkedIn profile states up front that he’s a convicted cybercriminal.

“I hope my work can help to change the minds of somebody, and if at least one person can change and turn to do good, I’m happy,” Ngo said. “It’s time for me to do something right, to give back to the world, because I know I can do something like this.”

Still, the recidivism rate among cybercriminals tends to be extremely high, and it would be easy for him to slip back into his old ways. After all, few people know as well as he does how best to exploit access to identity data.

O’Neill said he believes Ngo probably will keep his nose clean. But he added that Ngo’s service if it existed today probably would be even more successful and lucrative given the sheer number of scammers involved in using stolen identity data to defraud states and the federal government out of pandemic assistance loans and unemployment insurance benefits.

“It doesn’t appear he’s looking to get back into that life of crime,” O’Neill said. “But I firmly believe the people doing fraudulent small business loans and unemployment claims cut their teeth on his website. He was definitely the new coin of the realm.”

Ngo maintains he has zero interest in doing anything that might send him back to prison.

“Prison is a difficult place, but it gave me time to think about my life and my choices,” he said. “I am committing myself to do good and be better every day. I now know that money is just a part of life. It’s not everything and it can’t bring you true happiness. I hope those cybercriminals out there can learn from my experience. I hope they stop what they are doing and instead use their skills to help make the world better.”

Confessions of an ID Theft Kingpin, Part II

Yesterday’s piece told the tale of Hieu Minh Ngo, a hacker the U.S. Secret Service described as someone who caused more material financial harm to more Americans than any other convicted cybercriminal. Ngo was recently deported back to his home country after serving more than seven years in prison for running multiple identity theft services. He now says he wants to use his experience to convince other cybercriminals to use their skills for good. Here’s a look at what happened after he got busted.

Hieu Minh Ngo, 29, in a recent photo.

Part I of this series ended with Ngo in handcuffs after disembarking a flight from his native Vietnam to Guam, where he believed he was going to meet another cybercriminal who’d promised to hook him up with the mother of all consumer data caches.

Ngo had been making more than $125,000 a month reselling ill-gotten access to some of the biggest data brokers on the planet. But the Secret Service discovered his various accounts at these data brokers and had them shut down one by one. Ngo became obsessed with restarting his business and maintaining his previous income. By this time, his ID theft services had earned roughly USD $3 million.

As this was going on, Secret Service agents used an intermediary to trick Ngo into thinking he’d trodden on the turf of another cybercriminal. From Part I:

The Secret Service contacted Ngo through an intermediary in the United Kingdom — a known, convicted cybercriminal who agreed to play along. The U.K.-based collaborator told Ngo he had personally shut down Ngo’s access to Experian because he had been there first and Ngo was interfering with his business.

“The U.K. guy told Ngo, ‘Hey, you’re treading on my turf, and I decided to lock you out. But as long as you’re paying a vig through me, your access won’t go away’,” the Secret Service’s Matt O’Neill recalled.

After several months of conversing with his apparent U.K.-based tormentor, Ngo agreed to meet him in Guam to finalize the deal. But immediately after stepping off of the plane in Guam, he was apprehended by Secret Service agents.

“One of the names of his identity theft services was findget[.]me,” O’Neill said. “We took that seriously, and we did like he asked.”

In an interview with KrebsOnSecurity, Ngo said he spent about two months in a Guam jail awaiting transfer to the United States. A month passed before he was allowed a 10 minute phone call to his family and explain what he’d gotten himself into.

“This was a very tough time,” Ngo said. “They were so sad and they were crying a lot.”

First stop on his prosecution tour was New Jersey, where he ultimately pleaded guilty to hacking into MicroBilt, the first of several data brokers whose consumer databases would power different iterations of his identity theft service over the years.

Next came New Hampshire, where another guilty plea forced him to testify in three different trials against identity thieves who had used his services for years. Among them was Lance Ealy, a serial ID thief from Dayton, Ohio who used Ngo’s service to purchase more than 350 “fullz” — a term used to describe a package of everything one would need to steal someone’s identity, including their Social Security number, mother’s maiden name, birth date, address, phone number, email address, bank account information and passwords.

Ealy used Ngo’s service primarily to conduct tax refund fraud with the U.S. Internal Revenue Service (IRS), claiming huge refunds in the names of ID theft victims who first learned of the fraud when they went to file their taxes and found someone else had beat them to it.

Ngo’s cooperation with the government ultimately led to 20 arrests, with a dozen of those defendants lured into the open by O’Neill and other Secret Service agents posing as Ngo.

The Secret Service had difficulty pinning down the exact amount of financial damage inflicted by Ngo’s various ID theft services over the years, primarily because those services only kept records of what customers searched for — not which records they purchased.

But based on the records they did have, the government estimated that Ngo’s service enabled approximately $1.1 billion in new account fraud at banks and retailers throughout the United States, and roughly $64 million in tax refund fraud with the states and the IRS.

“We interviewed a number of Ngo’s customers, who were pretty open about why they were using his services,” O’Neill said. “Many of them told us the same thing: Buying identities was so much better for them than stolen payment card data, because card data could be used once or twice before it was no good to them anymore. But identities could be used over and over again for years.”

O’Neill said he still marvels at the fact that Ngo’s name is practically unknown when compared to the world’s most infamous credit card thieves, some of whom were responsible for stealing hundreds of millions of cards from big box retail merchants.

“I don’t know of anyone who has come close to causing more material harm than Ngo did to the average American,” O’Neill said. “But most people have probably never heard of him.”

Ngo said he wasn’t surprised that his services were responsible for so much financial damage. But he was utterly unprepared to hear about the human toll. Throughout the court proceedings, Ngo sat through story after dreadful story of how his work had ruined the financial lives of people harmed by his services.

“When I was running the service, I didn’t really care because I didn’t know my customers and I didn’t know much about what they were doing with it,” Ngo said. “But during my case, the federal court received like 13,000 letters from victims who complained they lost their houses, jobs, or could no longer afford to buy a home or maintain their financial life because of me. That made me feel really bad, and I realized I’d been a terrible person.”

Even as he bounced from one federal detention facility to the next, Ngo always seemed to encounter ID theft victims wherever he went, including prison guards, healthcare workers and counselors.

“When I was in jail at Beaumont, Texas I talked to one of the correctional officers there who shared with me a story about her friend who lost her identity and then lost everything after that,” Ngo recalled. “Her whole life fell apart. I don’t know if that lady was one of my victims, but that story made me feel sick. I know now that was I was doing was just evil.”

Ngo’s former ID theft service usearching[.]info.


The Vietnamese hacker was released from prison a few months ago, and is now finishing up a mandatory three-week COVID-19 quarantine in a government-run facility near Ho Chi Minh city. In the final months of his detention, Ngo started reading everything he could get his hands on about computer and Internet security, and even authored a lengthy guide written for the average Internet user with advice about how to avoid getting hacked or becoming the victim of identity theft.

Ngo said while he would like to one day get a job working in some cybersecurity role, he’s in no hurry to do so. He’s already had at least one job offer in Vietnam, but he turned it down. He says he’s not ready to work yet, but is looking forward to spending time with his family — and specifically with his dad, who was recently diagnosed with Stage 4 cancer.

Longer term, Ngo says, he wants to mentor young people and help guide them on the right path, and away from cybercrime. He’s been brutally honest about his crimes and the destruction he’s caused. His LinkedIn profile states up front that he’s a convicted cybercriminal.

“I hope my work can help to change the minds of somebody, and if at least one person can change and turn to do good, I’m happy,” Ngo said. “It’s time for me to do something right, to give back to the world, because I know I can do something like this.”

Still, the recidivism rate among cybercriminals tends to be extremely high, and it would be easy for him to slip back into his old ways. After all, few people know as well as he does how best to exploit access to identity data.

O’Neill said he believes Ngo probably will keep his nose clean. But he added that Ngo’s service if it existed today probably would be even more successful and lucrative given the sheer number of scammers involved in using stolen identity data to defraud states and the federal government out of pandemic assistance loans and unemployment insurance benefits.

“It doesn’t appear he’s looking to get back into that life of crime,” O’Neill said. “But I firmly believe the people doing fraudulent small business loans and unemployment claims cut their teeth on his website. He was definitely the new coin of the realm.”

Ngo maintains he has zero interest in doing anything that might send him back to prison.

“Prison is a difficult place, but it gave me time to think about my life and my choices,” he said. “I am committing myself to do good and be better every day. I now know that money is just a part of life. It’s not everything and it can’t bring you true happiness. I hope those cybercriminals out there can learn from my experience. I hope they stop what they are doing and instead use their skills to help make the world better.”

U.S. Secret Service Warns ID Thieves are Abusing USPS’s Mail Scanning Service

A year ago, KrebsOnSecurity warned that “Informed Delivery,” a new offering from the U.S. Postal Service (USPS) that lets residents view scanned images of all incoming mail, was likely to be abused by identity thieves and other fraudsters unless the USPS beefed up security around the program and made it easier for people to opt out. This week, the U.S. Secret Service issued an internal alert warning that many of its field offices have reported crooks are indeed using Informed Delivery to commit various identity theft and credit card fraud schemes.

Image: USPS

The internal alert — sent by the Secret Service on Nov. 6 to its law enforcement partners nationwide — references a recent case in Michigan in which seven people were arrested for allegedly stealing credit cards from resident mailboxes after signing up as those victims at the USPS’s Web site.

According to the Secret Service alert, the accused used the Informed Delivery feature “to identify and intercept mail, and to further their identity theft fraud schemes.”

“Fraudsters were also observed on criminal forums discussing using the Informed Delivery service to surveil potential identity theft victims,” the Secret Service memo reads.

The USPS did not respond to repeated requests for comment over the past six days.

The Michigan incident in the Secret Service alert refers to the September 2018 arrest of seven people accused of running up nearly $400,000 in unauthorized charges on credit cards they ordered in the names of residents. According to a copy of the complaint in that case (PDF), the defendants allegedly stole the new cards out of resident mailboxes, and then used them to fraudulently purchase gift cards and merchandise from department stores.

KrebsOnSecurity took the USPS to task last year in part for not using its own unique communications method — the U.S. Mail — to validate and notify residents when someone at their address signs up for Informed Delivery. The USPS addressed that shortcoming earlier this year, announcing it had started alerting all households by mail whenever anyone signs up to receive scanned notifications of mail delivered to their address.

However, it appears that ID thieves have figured out ways to hijack identities and order new credit cards in victims’ names before the USPS can send their notification — possibly by waiting until the cards are already approved and ordered before signing up for Informed Delivery in the victim’s name.

Last month, WKMG’s Clickorlando.com wrote that a number of Belle Isle, Fla. residents reported receiving hefty bills for credit cards they never knew they had. One resident was quoted as saying she received a bill for $2,000 in charges on a card she’d never seen before, and only after that did she get a notice from the USPS saying someone at her address had signed up for Informed Delivery. The only problem was she’d never signed up for the USPS program.

“According to a police report, someone opened fraudulent credit card accounts and charged more than $14,000 and signed her neighbors up for Informed Delivery, too,” Clickorlando’s Louis Bolden explained. “Photos of what would be in their mail were going to someone else.”

Residents in Texas have reported similar experiences. Dave Lieber, author of The Watchdog column for The Dallas Morning News, said he heard from victim Chris Torraca, 58, a retired federal bank regulator from Grapevine, a town between Dallas and Ft. Worth.

“Chris discovered it after someone created an account in his name at usps.com,” Lieber wrote in a post published Nov. 2. “The thief began receiving photos of Chris’ mail and also opened a bank credit card in Chris’ wife’s name. Postal officials promote the program as a great way to prevent ID theft, but for Chris, that’s what led to it.”

As noted in last year’s story, the major weakness with Informed Delivery lies in the method the USPS uses to validate new accounts. Signing up requires an eligible resident to create a free user account at USPS.com, which asks for the resident’s name, address and an email address. The final step in validating residents involves answering four so-called “knowledge-based authentication” or KBA questions.

KrebsOnSecurity has relentlessly assailed KBA as an unreliable authentication method because so many answers to the multiple-guess questions are available on sites like Spokeo and Zillow, or via social networking profiles.

I’ve previously advised that having a security freeze on your credit file should be enough to prevent someone from registering an Informed Delivery account in your name. That’s because the USPS validates new users by asking them a series of multiple-guess questions chosen by big-three credit bureau Equifax.

But numerous readers have responded that they were still able to sign up for the service even though they had security freezes in place with Equfiax and the two other major consumer credit bureaus (Experian and TransUnion).

Normally in these cases, I’d urge readers to simply plant their flag by registering an account to claim their address. However, the USPS allows new account creations for anyone currently able to receive mail at your address, which means that claiming your address may involve registering an account with every adult present at your address.

The Dallas Morning News piece referenced earlier says Americans can opt-out of Informed Delivery by emailing the “eSafe Team” at USPS at eSafe@usps.gov. However, emails sent to this address by KrebsOnSecurity elicited no response over the past four days.

Yet, one reader received a curious response by emailing the customer service address advertised by USPS’s Informed Delivery service — informeddelivery@custhelp.com. That reader requested that USPS remove her address from eligibility for Informed Delivery, and asked the Postal Service to let her know if anyone had previously signed up for the service at her address.

According to an email shared with this author, the USPS’s customer help team responded by asking the resident to answer some of her KBA questions in plain text via email.

A response from the Informed Delivery division of the USPS’s customer service department.

Sources tell KrebsOnSecurity that the USPS is now processing some 20,000 new Informed Delivery account registrations each day, and that the USPS is continuously deleting new account registrations that it believes may be fraudulent.

There is also a potentially new security wrinkle in the USPS’s Informed Delivery service. The USPS is now generating revenue by allowing third-party companies to advertise interactive content in Informed Delivery communications (PDF) sent to email subscribers.

The program allows the USPS to automatically match scanned mail images to specific advertising campaigns. According to a review of its mailer delivery user guide (PDF), this initiative allows advertisers to publicize content that contains interactive links, which could be abused by malefactors posing as legitimate advertisers.

This graphic, taken from the Secret Service alert, describes how the USPS Informed Delivery system works.