Spammers get bullish on stocks

Researching the impact of bot software and Trojan horses is what Joe Stewart does.

The senior security researcher at SecureWorks has reverse engineered bot software and purposely infected his own systems to monitor what goes on in the illicit networks. When he came across a copy of Rustock, a program that drafts PCs into botnet armies, he decided to take a look into how the program was being used.

"Rustock is very advanced in the amount of stealth is uses once it is on the system," Stewart said in an interview with SecurityFocus. "When it first came out, people were warning because it was a new rootkit, but its spam features are also interesting."

Stewart found that his Rustock-infected system received spam for a single stock, that of Diamant Art. The spam message, which took the form of an email with an embedded image touting the stock, came into his compromised system on the weekend before Monday, 18 December, with a command to start the spam campaign.

Stewart researched the stock activity for the company and found that the week before, more than 11.5m shares were bought on a single day for anywhere from $0.0008 and $0.0011 a share. A normal trading day rarely saw more than a tenth of those shares trade hands.

On 18 December, a Monday, the market opened to brisk trading in Diamant Art's stock, driving the price to a peak of $0.0025. If the 11.5m shares were sold at the peak for more than $28,000, the sellers may have made more than $18,000 for a single week's worth of effort.

The profit, while modest for cybercrime, underscored the appeal of stock spam, Stewart said in a blog post on the research.

"I wonder if the spams touting Viagra and Rolexes have ever made that much profit so quickly for the spammers with so little effort and almost zero overhead," he wrote. "It's little wonder why stock spam is taking over."

In the second half of 2006, a program called SpamThru drove a large increase in stock spam using a botnet of more than 70,000 computers. There is some evidence that the same Russian spammers behind that increase are replacing the SpamThru software with the latest bot program, Rustock, according to Matt Sergeant, senior anti-spam technologist with mail service provider MessageLabs.

"Rustock seems to be one of the most popular bot programs at the moment," Sergeant said. "It probably is a successor to the earlier stock spam program, SpamThru. It is probably written by the same crew."

Rustock, which appeared in June 2006, brings together a host of features found in other malicious software, making the program difficult to detect and remove. The software has rootkit-like features, hiding itself among the components of the Windows operating system. The program also uses polymorphism, changing itself each time it infects a system in order to avoid antivirus software. Moreover, a bot net created using Rustock sends out messages with random words and an image with the actual message. Such image spam is difficult for antispam software to detect and block.

The technical knowledge exhibited by the writer of the program makes it unlikely that the person is actually committing the attack, but part of a specialised team, said David Cole, director of Symantec's Security Response team.

"The person that wrote Rustock had a deep technical knowledge of how anti-virus and anti-rootkit technology works today," Cole said. "A person with that sort of knowledge is not going to be thinking about a stock pump-and-dump scam. The whole attack is probably involves multiple people."

Because the bot software does not take commands through chat rooms but uses the language of the World Wide Web, the Hypertext Transfer Protocol or HTTP, SecureWork's Stewart could not eavesdrop on the people controlling the bot net. He could merely watch what his compromised computer downloaded and was asked to do.

While such difficulties could inhibit investigating the fraudsters behind the Diamant Art pump-and-dump scheme, stock transactions allow the US Securities and Exchange Commission (SEC) to use other methods to track down the suspects.

"The bottom line is that investigations are basically gumshoe work," said the SEC's Stark. "You track all three trails - the money trail, the trading trail, and the internet infrastructure trail - and you see where it leads."

In some cases, the best the SEC can do is block the profits from such scheme from reaching the fraudsters. In December, the regulatory agency filed a civil case against an alleged account intruder, charging that the person used their access to victims' PCs to liquidate assets in their portfolios and use that money to buy a targeted stock and pump up the security's price. In more than two dozen schemes, the suspected fraudsters made more than $353,000, according to the SEC.

Yet, average consumers should not look to cash in. For anyone considering investing in a stock because they get an email touting the security, Stark's advice is black and white.

"We have been very good at telling people that you shouldn't invest in a security touted by a spam," he said. "It should treated like a flyer that you find on your windshield - either rip it up or notify us."

This article originally appeared in Security Focus.

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