Adobe said it suffered a sustained compromise of its corporate network, allowing hackers to illegally access source code for several of its widely used software applications as well as password data and other sensitive information belonging to almost three million customers.

Adobe dropped the bombshell revelation shortly after Krebs on Security's Brian Krebs reported that the hack began sometime in mid-August and was carried out by the same criminals who breached LexisNexis and other major US data brokers. In the course of investigating the earlier intrusions, Krebs said he happened upon a 40 gigabyte trove of source code, much of it belonging to Adobe. Adobe confirmed its ColdFusion Web application software and its Acrobat document program were among those that were stolen.

A new generation of exploits

The Acrobat software family, which is intimately linked to the nearly ubiquitous Reader application, has long been a favorite target of malware developers looking for ways to sneak their malicious wares onto people's computers. The specter of hackers having full access to the raw source code of those applications is troubling, because it could make it easier to identify bugs that can be surreptitiously exploited in drive-by website attacks.

"This breach poses a serious concern to countless businesses and individuals," a statement issued by Hold Security, which assisted in Krebs' investigation, warned. "While we are not aware of specific use of data from the source code, we fear that disclosure of encryption algorithms, other security schemes, and software vulnerabilities can be used to bypass protections for individual and corporate data. Effectively, this breach may have opened a gateway for a new generation of viruses, malware, and exploits."

Adobe Chief Security Officer Brad Arkin said officials aren't aware of any unpatched vulnerabilities being targeted in any of the company's products. "However, as always, we recommend customers run only supported versions of the software, apply all available security updates, and follow the advice of the Acrobat Enterprise Toolkit and the ColdFusion Lockdown Guide," he added. He thanked Krebs and Alex Holden of Hold Security for their help in responding to the intrusion.

Krebs said Adobe engineers are still in the process of checking on the integrity of its source code. The investigation includes looking for "anomalous check-in activity on its code repositories," which could indicate the intruders were able to introduce backdoors or security bugs or otherwise tamper with the underlying applications.

"We are looking at malware analysis and exploring the different digital assets we have," Arkin told Krebs. "Right now the investigation is really into the trail of breadcrumbs of where the bad guys touched."

In an advisory, Arkin said attackers removed information for 2.9 million customers from company computers. That data included customer names, encrypted credit or debit card numbers, expiration dates, and other information relating to orders. Attackers also accessed customer IDs and "encrypted" (by which Adobe probably means cryptographically hashed) passwords. Customer passwords will be reset, and Arkin recommended customers change passwords on other sites if they matched those used in their Adobe accounts. Arkin said company employees have notified banks that process customer payments so they can work with payment card companies and card-issuing banks to protect customer accounts.

Krebs said that one of the related intrusions he uncovered—into the network of the National White Collar Crime Center—appears to have been initiated by exploiting weaknesses in Adobe's ColdFusion product. While Adobe plugged all known security holes in the product a few months ago, many networks run outdated versions that expose the users to serious hacks. "This indeed may have also been the vector that attackers used to infiltrate Adobe's own networks," Krebs said.