Posts Tagged: University of California

Dec 14

Treasury Dept: Tor a Big Source of Bank Fraud

A new report from the U.S. Treasury Department found that a majority of bank account takeovers by cyberthieves over the past decade might have been thwarted had affected institutions known to look for and block transactions coming through Tor, a global communications network that helps users maintain anonymity by obfuscating their true location online.

The findings come in a non-public report obtained by KrebsOnSecurity that was produced by the Financial Crimes Enforcement Network (FinCEN), a Treasury Department bureau responsible for collecting and analyzing data about financial transactions to combat domestic and international money laundering, terrorist financing and other financial crimes.

In the report, released on Dec. 2, 2014, FinCEN said it examined some 6,048 suspicious activity reports (SARs) filed by banks between August 2001 and July 2014, searching the reports for those involving one of more than 6,000 known Tor network nodes. Investigators found 975 hits corresponding to reports totaling nearly $24 million in likely fraudulent activity.

“Analysis of these documents found that few filers were aware of the connection to Tor, that the bulk of these filings were related to cybercrime, and that Tor related filings were rapidly rising,” the report concluded. “Our BSA [Bank Secrecy Act] analysis of 6,048 IP addresses associated with the Tor darknet [link added] found that in the majority of the SAR filings, the underlying suspicious activity — most frequently account takeovers — might have been prevented if the filing institution had been aware that their network was being accessed via Tor IP addresses.”

Tables from the FinCEN report.

Tables from the FinCEN report.

FinCEN said it was clear from the SAR filings that most financial institutions were unaware that the IP address where the suspected fraudulent activity occurred was in fact a Tor node.

“Our analysis of the type of suspicious activity indicates that a majority of the SARs were filed for account takeover or identity theft,” the report noted. “In addition, analysis of the SARs filed with the designation ‘Other revealed that most were filed for ‘Account Takeover,’ and at least five additional SARs were filed incorrectly and should have been ‘Account Takeover.'”

The government also notes that there has been a fairly recent and rapid rise in the number of SAR filings over the last year involving bank fraud tied to Tor nodes.

“From October 2007 to March 2013, filings increased by 50 percent,” the report observed. “During the most recent period — March 1, 2013 to July 11, 2014 — filings rose 100 percent.” Continue reading →

Oct 14

Silk Road Lawyers Poke Holes in FBI’s Story

New court documents released this week by the U.S. government in its case against the alleged ringleader of the Silk Road online black market and drug bazaar suggest that the feds may have some ‘splaining to do.

The login prompt and CAPTCHA from the Silk Road home page.

The login prompt and CAPTCHA from the Silk Road home page.

Prior to its disconnection last year, the Silk Road was reachable only via Tor, software that protects users’ anonymity by bouncing their traffic between different servers and encrypting the traffic at every step of the way. Tor also lets anyone run a Web server without revealing the server’s true Internet address to the site’s users, and this was the very technology that the Silk road used to obscure its location.

Last month, the U.S. government released court records claiming that FBI investigators were able to divine the location of the hidden Silk Road servers because the community’s login page employed an anti-abuse CAPTCHA service that pulled content from the open Internet — thus leaking the site’s true Internet address.

But lawyers for alleged Silk Road captain Ross W. Ulbricht (a.k.a. the “Dread Pirate Roberts”) asked the court to compel prosecutors to prove their version of events.  And indeed, discovery documents reluctantly released by the government this week appear to poke serious holes in the FBI’s story.

Continue reading →

Aug 13

Buying Battles in the War on Twitter Spam

The success of social networking community Twitter has given rise to an entire shadow economy that peddles dummy Twitter accounts by the thousands, primarily to spammers, scammers and malware purveyors. But new research on identifying bogus accounts has helped Twitter to drastically deplete the stockpile of existing accounts for sale, and holds the promise of driving up costs for both vendors of these shady services and their customers.



Twitter prohibits the sale and auto-creation of accounts, and the company routinely suspends accounts created in violation of that policy. But according to researchers from George Mason University, the International Computer Science Institute and the University of California, Berkeley, Twitter traditionally has done so only after these fraudulent accounts have been used to spam and attack legitimate Twitter users.

Seeking more reliable methods of detecting auto-created accounts before they can be used for abuse, the researchers approached Twitter last year for the company’s blessing to purchase credentials from a variety of Twitter account merchants. Permission granted, the researchers spent more than $5,000 over ten months buying accounts from at least 27 different underground sellers.

In a report to be presented at the USENIX security conference in Washington, D.C. today, the research team details its experience in purchasing more than 121,000 fraudulent Twitter accounts of varying age and quality, at prices ranging from $10 to $200 per one thousand accounts.

The research team quickly discovered that nearly all fraudulent Twitter account merchants employ a range of countermeasures to evade the technical hurdles that Twitter erects to stymie the automated creation of new accounts.

“Our findings show that merchants thoroughly understand Twitter’s existing defenses against automated registration, and as a result can generate thousands of accounts with little disruption in availability or instability in pricing,” the paper reads. “We determine that merchants can provide thousands of accounts within 24 hours at a price of $0.02 – $0.10 per account.”


For example, to fulfill orders for fraudulent Twitter accounts, merchants typically pay third-party services to help solve those squiggly-letter CAPTCHA challenges. I’ve written here and here about these virtual sweatshops, which rely on low-paid workers in China, India and Eastern Europe who earn pennies per hour deciphering the puzzles.

topemailThe Twitter account sellers also must verify new accounts with unique email addresses, and they tend to rely on services that sell cheap, auto-created inboxes at HotmailYahoo and, the researchers found. “The failure of email confirmation as a barrier directly stems from pervasive account abuse tied to web mail providers,” the team wrote. “60 percent of the accounts were created with Hotmail, followed by and”

Bulk-created accounts at these Webmail providers are among the cheapest of the free email providers, probably because they lack additional account creation verification mechanisms required by competitors like Google, which relies on phone verification. Compare the prices at this bulk email merchant: 1,000 Yahoo accounts can be had for $10 (1 cent per account), and the same number Hotmail accounts go for $12. In contrast, it costs $200 to buy 1,000 Gmail accounts.

topcountriesFinally, the researchers discovered that Twitter account merchants very often spread their new account registrations across thousands of Internet addresses to avoid Twitter’s IP address blacklisting and throttling. They concluded that some of the larger account sellers have access to large botnets of hacked PCs that can be used as proxies during the registration process.

“Our analysis leads us to believe that account merchants either own or rent access to thousands of compromised hosts to evade IP defenses,” the researchers wrote.

Damon McCoy, an assistant professor of computer science at GMU and one of the authors of the study, said the top sources of the proxy IP addresses were computers in developing countries like India, Ukraine, Thailand, Mexico and Vietnam.  “These are countries where the price to buy installs [installations of malware that turns PCs into bots] is relatively low,” McCoy said.

Continue reading →

Oct 12

Rogue Pharma, Fake AV Vendors Feel Credit Card Crunch

New research suggests that companies behind some of America’s best known consumer brands may be far more effective at fighting cybercrime than any efforts to enact more stringent computer security and anti-piracy laws.

Recent legislative proposals in the United States — such as the Stop Online Piracy Act —  have sought to combat online trafficking in copyrighted intellectual property and counterfeit goods by granting Internet service providers and authorities broader powers to prosecute offenders, and by imposing stronger criminal penalties for such activity. But recent data collected by academic researchers suggests that brand holders already have the tools to quash much of this activity.

Over the past two years, a team of academic researchers made hundreds of “test buys” at Web sites from 40 different shady businesses peddling knockoff prescription drugs, counterfeit software and fake antivirus products. The researchers, from George Mason University, the International Computer Science Institute, and the University of California, San Diego, posed as buyers for these products, which tend to be promoted primarily via hacked Web sites, junk email and computer viruses.

Test buys showed relationships between 40 affiliate programs and 25 banks, although a majority of the transactions filtered through a handful of banks in Azerbaijan, China, Georgia, Latvia, and Mauritius.

The test buys were intended to reveal relationships between the shadowy merchants and the banks that process credit and debit card transactions for these businesses. Following the money trail showed that a majority of the purchases were processed by just 12 banks in a handful of countries, including Azerbaijan, China, Georgia, Latvia, and Mauritius.

The researchers said they submitted the test buy results to a database run by the International AntiCounterfeiting Coalition, (IACC), a Washington, D.C.-based non-profit organization devoted to combating product counterfeiting and piracy. Several pharmacy and software vendors and IACC members whose trademarks were infringed in those transactions (the researchers said non-disclosure agreements prohibit them from naming the brands) used the data to lodge complaints with Visa (only Visa-branded debit cards were used to make the test buys).

Contracts between the banks and Visa and MasterCard stipulate that merchants are prohibiting from selling goods and services that are illegal in the country into which those goods or services are being sold. The credit card associations have a standard process for accepting complaints about such transactions, in which they warn the online merchant’s bank (including a notice of potential fines for noncompliance). After a complaint about such activity, the merchant’s bank conducts its investigation, and may choose to contest the issue if they believe it is in error. But if the bank decides not to challenge the complaint, then they will need to take action to prevent future such transactions, or else face an escalating series of fines from the card associations.

The researchers noticed that in case after case, merchant accounts that were used in fraudulent activity for some extended period of time before they filed a complaint with the IACC generally stopped being used within one month after a complaint was lodged. Neither Visa nor the IACC responded to requests for comment on this story.

Stefan Savage, a professor at UCSD’s Department of Computer Science and Engineering, said the data suggests that the private sector can have a major impact on cybercrime merely by going after the funding for these operations.

It doesn’t require a judge, a law-enforcement officer or even much in the way of sophisticated security capabilities.  If you can purchase a product, then there’s a record of it and that record points back to the merchant account getting the money,” Savage said. “Visa and MasterCard frown on sales of illegal purchases made on their networks and will act appropriately on complaints from brandholders based on undercover purchases.”

Savage said it doesn’t take concerted action by all of the affected brands to have a major impact on the rogue businesses that incentivize this type of commerce. On the contrary, he said one software brandholder pursued the merchant banks tied to all of the group’s test buys for its products with such a ferocity and swiftness that it virtually shut down the market for pirated brand name software [a.k.a “OEM”] overnight.

“This vendor went after everything. They did it so quickly — and not only for their own products — that it all but shut down the entire OEM ecosystem,” Savage said. “A couple of [OEM affiliate programs] survived by getting rid of that company’s brand, but in the beginning, when people had no clue what’s going on, it shut down the entire business for everyone.”


The researchers note that in mid-2011, Visa made a series of changes to their operating regulations that seem designed to specifically target on-line pharmacies and sellers of counterfeit goods. First, sales of goods categorized as pharmaceutical-related were explicitly classified as “high risk” (along with gambling and various kinds of direct marketing services), and acquirers issuing new contracts for high-risk e-commerce merchants required significantly more due diligence (including $100M in equity capital and good standing in risk management programs). Also, the new documents explicitly call out examples of illegal transactions including “Unlawful sale of prescription drugs,” and “Sale of counterfeit or trademark-infringing products or services,” among others. Finally, these changes include more aggressive fine schedules for noncompliance.

Some of the best evidence of the success of the test buys+complaints strategy comes directly from the folks operating the affiliate programs that reward spammers and miscreants for promoting fake antivirus, pirated software and dodgy pill sites. In June 2012, a leader of one popular pharmacy affiliate program posted a lengthy message to, a Russian language forum that caters to a variety of such affiliate programs. In that discussion thread, which is now some 234 pages long, the affiliate program manager explains to a number of mystified forum members why the pharmacy programs have had so much trouble maintaining reliable credit card processing. Continue reading →

Feb 12

Who’s Behind the World’s Largest Spam Botnet?

A Wikileaks-style war of attrition between two competing rogue Internet pharmacy gangs has exposed some of the biggest spammers on the planet. The latest casualties? Several individuals likely responsible for running Grum, currently the world’s most active spam botnet.

Grum is the top spam botnet, according to M86Security

In the summer of 2010, hackers stole and leaked the database for SpamIt and Glavmed, sister programs that paid people to promote fly-by-night online pharmacies. According to that data, the second-most successful affiliate in SpamIt was a member nicknamed “GeRa.” Over a 3-year period, GeRa’s advertisements and those of his referrals resulted in at least 80,000 sales of knockoff pharmaceuticals, brought SpamIt revenues of in excess of $6 million, and earned him and his pals more than $2.7 million.

A variety of data indicate that GeRa is the lead hacker behind Grum, a spam botnet that can send more than 18 billion emails a day and is the primary vehicle for more than a third of all junk email.

Hackers bent on undermining SpamIt leaked thousands of chats between SpamIt members and Dmitry Stupin, the co-administrator of the program. The chats show daily communication between GeRa and Stupin; the conversations were usually about setting up new spamming operations or fixing problems with existing infrastructure. In fact, Stupin would remark that GeRa was by far the most bothersome of all the program’s top spammers, telling a fellow SpamIt administrator that, “Neither Docent [Mega-D botmaster] nor Cosma [Rustock botmaster] can compare with him in terms of trouble with hosting providers.”

Several of those chats show GeRa pointing out issues with specific Internet addresses that would later be flagged as control servers for the Grum botnet. For example, in a chat with Stupin on June 11, 2008, GeRa posts a link to the address Then after checking the server, he proceeds to tell Stupin how many infected PCs were phoning home to that address at the time. That same server has long been identified as a Grum controller.

By this time, Grum had grown to such an established threat that it was named in the Top Spam Botnets Exposed paper released by Dell SecureWorks researcher Joe Stewart. On  April 13, 2008 – just five days after Stewart’s analysis was released –  GeRa would post a link to it into a chat with Stupin, saying “Haha, I am also on the list!” Continue reading →

Jul 11

Which Banks Are Enabling Fake AV Scams?

Fake antivirus scams and rogue Internet pharmacies relentlessly seek customers who are willing to trade their credit card numbers for a remedy. Banks and financial institutions become partners in crime when they process payments to fraudsters.

Published research has shown that rogue Internet pharmacies and spam would be much less prevalent and profitable if a few top U.S. financial institutions stopped processing payments for dodgy overseas banks. This is also true for fake antivirus scams, which use misleading security alerts to frighten people into purchasing worthless security software.

Researchers from the University of California, Santa Barbara spent several months infiltrating three of the most popular fake antivirus (fake AV) “affiliate” networks, organized criminal operations that pay hackers to deploy the bunk software. The researchers uncovered a peculiar credit card processing pattern that was common to these scams; a pattern that Visa and MasterCard could use to detect and blacklist fake AV processors.

The pattern reflects each fake AV program’s desire to minimize the threat from “chargebacks,” which occur when consumers dispute a charge. The fake AV networks the UCSB team infiltrated tried to steer unhappy buyers to live customer support agents who could be reached via a toll-free number or online chat. When customers requested a refund, the fake AV firm either ignored the request or granted a refund. If the firm ignored the request, then the buyer could still contact their credit card provider to obtain satisfaction by initiating a chargeback; the credit card network grants a refund to the buyer and then forcibly collects the funds from the firm by reversing the charge.

Excessive chargebacks (more than 2-3 percent of sales) generally raise red flags at Visa and MasterCard, which employ a sliding scale of financial penalties for firms that generate too many chargebacks. But the fake AV companies also don’t want to issue refunds voluntarily if they think a customer won’t take the next step of requesting a chargeback.

The UCSB team found that the fake AV operations sought to maximize profits by altering their refunds according to the chargebacks reported against them, and by refunding just enough to remain below a payment processor’s chargeback limits. Whenever the rate of chargebacks increased, the miscreants would begin issuing more refunds. When the rate of chargebacks subsided, the miscreants would again withhold refunds. Consider the following diagram, from the researchers’ report, which shows a direct and very close correlation between increased chargebacks and heightened refund rates.

The researchers found that fraudsters offered more refunds (dotted line) as chargebacks (red) spiked.

Continue reading →

Jun 11

Banks Hold Key to Killing Rogue Pharmacies

More than half of all sales at the world’s largest rogue Internet pharmacy in the last four years were charged to credit and debit cards issued by the top seven card-issuing banks, new research suggests.

Unlicensed pharmacies create public health risks and confuse consumers who are looking for safe and reliable prescription medicines. Rogue pharma Web sites are primarily advertised with the help of spam, malicious software, and hacked Web sites. Curbing this drug dealing activity would promote both public health and Internet users’ safety.

Recent findings highlight additional levers that policymakers could use to curb sales at rogue online pharmacies, by convincing the card-issuing banks to stop accepting these charges or by enacting legislation similar to that used to squelch online gambling operations.

The figures shown below come from sales data stolen from Glavmed, a Russian affiliate program that pays webmasters to host and promote online pharmacy sites that sell a variety of prescription drugs without requiring a prescription. Last summer, a source sent KrebsOnSecurity a copy of the Glavmed database, which includes credit card numbers and associated buyer information for nearly $70 million worth of sales at Glavmed sites between 2006 and 2010.

I sorted the buyer data by bank identification number (BIN), indicated by the first six digits in each credit or debit card number. My analysis shows that at least 15 percent of all Glavmed purchases — approximately $10.7 million in rogue pill buys — were made with cards issued by Bank of America.

The Glavmed sales using cards issued by the top seven credit card issuers were almost certainly higher than listed in the chart above.  About 12 percent of the Glavmed sales could not be categorized by bank ID number (some card issuers may have been absorbed into larger banks). Hence, the analysis considers only the 88 percent of Glavmed transactions for which the issuing bank was known. More significantly, the figures in this the analysis do not include close to $100 million in sales generated during that same time period by, a now defunct sister program of Glavmed whose members mainly promoted rogue pharmacies via junk e-mail; the leaked database did not contain credit or debit card numbers for those purchase records. Continue reading →