Pfizer’s computer network is spamming the Internet with e-mails and touting Viagra, along with ads for knockoff Rolexes and shady junk stocks, Wired reports, adding that the e-mails aren’t part of Pfizer’s official marketing efforts.

The drugmaker’s computers appear to have been infected with malware that has transformed them into ‘zombie computers’ that send spam at the behest of a hacker. Oddly enough, they are spamming the public’s inboxes with ads for the company’s own product. “There is a disaster inside this company, and they don’t know it,” says Rick Wesson, CEO of Support Intelligence, a security company that alerted Wired News to the problem.

Much of the spam originating from Pfizer computers pretends to be sent from Gmail accounts, says Wesson. Products hocked include penis-enlargement products with the names “Mandik” and “Manster,” as well as Viagra, Ambien, Valium and Lilly’s Cialis.

Wesson says Pfizer computers have been spamming inboxes for the last six months and he’s kept 600 spam messages sent. He says 138 different Pfizer IP addresses have been blacklisted by various groups, but adds that he can’t estimate the number of infected machines without more info or installing monitoring equipment on the edge of Pfizer’s networks.

However, Pfizer appears to be unaware of the situation, despite several warnings from Support Intelligence. “If they (were aware), they would have taken care of the problem,” Wesson says. Pharmalot sent a note to a Pfizer spokesman seeking comment, but we have not yet heard back.

On Tuesday morning between 7 a.m. and 10 a.m., Pfizer’s network sent at least 20 messages about sex and penises, according to Wesson. The number of infected machines is impossible to determine, because much of the traffic comes from behind a firewall that obscures the machines’ internal IP addresses.

Support Intelligence tracks spam by monitoring inboxes at 250,000 website domains that it owns - opening those to allow any and all e-mail and tracking what they get. It also monitors communications to and from command-and-control centers, the computers hackers use to give instructions to a network of zombie computers known as a botnet.

Paul Ferguson works to fight botnets as a network architect for security giant Trend Micro. He says Support Intelligence does “great work” and acts responsibly in disclosing security problems. “They harvest valuable intelligence and share it with the security community,” Ferguson tells Wired. “They also do ‘due diligence’ showing that even large corporations are subject to security problems, and only do so when they exhaust other attempts at communicating to them that they have a problem.”

Support Intelligence says they’ve seen connections between botnet controllers and computers inside Pfizer’s network. “Pfizer sticks out like a glaring downed jet in a haystack,” Wesson says. “They constantly send us the most egregious spam. When there is this much smoke, there is a hell of a fire going on.”

Hat tip to PharmaGossip