Attacks/Breaches
11/22/2013
04:58 PM
Connect Directly
RSS
E-Mail
50%
50%
Repost This

CryptoLocker Could Herald Rise Of More Sophisticated Ransomware

A smarter approach to encryption is what separates CryptoLocker from other ransomware -- but that might not last long

Seven hundred and fifty dollars -- that is the amount of money it cost a police department in Massachusetts to regain access to its computer files. The culprit of this kidnap and ransom was the now-infamous CryptoLocker, which locked both images and Microsoft Word documents on the department's computer system.

While precise statistics are hard to come by, researchers at Symantec say they are seeing hundreds of thousands of spam email messages a day distributing the threat, with hundreds of infections per day. Ransomware scams are still in vogue, but where CryptoLocker makes its mark is its use of asymmetric encryption -- and don't be surprised if security vendors are not the only ones taking notice. Other attackers will move in this direction as well.

"It's not a revolution, but a natural evolution," says Lance James, head of intelligence at Vigilant by Deloitte. "Putting it bluntly, I think we expected this sooner and should be surprised it took so long. Yes, others will move in this direction, or they will sell CryptoLocker base code to enable the development of related ransomware, thus spawning in the underground a new widespread standard, if you will, for ransomware."

Unlike other ransomware, CryptoLocker's authors have properly implemented an asymmetric system (2048 bit RSA) and 256 bit AES-CBC using the native Microsoft Windows crypto system, which is the basis for legitimate tools such as BitLocker, he explains.

"Most encryption uses a symmetric [one key] key system or simply locks access to the files but does not fully encrypt the data," James says. "A reverse engineer can simply build tools that recover the key or leverage knowledge of how the software works to unlock the files. Encryption mechanisms found in other ransomware are of a homebrew variety -- they include errors and vulnerabilities that reversers and infosec professionals can identify, thereby enabling the creation of workarounds to neutralize the intent of the ransomeware."

Once on the system, the malware can encrypt files located within shared network drives, USB drives, external hard drives, network file shares, and even some cloud storage drives. If one computer on a network becomes infected, then mapped network drives could become infected as well. CryptoLocker then connects to the attackers' command-and-control server to put the asymmetric private encryption key "out of the victim's reach," according to a warning from US-CERT.

"I wouldn't say it is necessarily any more sophisticated, but perhaps just better executed," notes Chet Wisniewski, senior security adviser at Sophos. "They aren't pretending to be the cops. They are simply encrypting your files, demanding money, and mostly honoring their end of the bargain -- simple, straight to the point of extortion."

Ransomware that was popular early in the year didn't even perform encryption -- it just locked the screen with a "scary law enforcement message and demanded money," he adds.

Ransomware can be a very profitable type of operation. In a paper (PDF) released last year, Symantec estimated that one particular group was extorting nearly $400,000 a month from victims.

Ransomware attacks have been on the uptick for the past several quarters. According to McAfee's third quarter threat report (PDF), more than 312,000 new, unique samples were detected during that three-month period -- less than the previous quarter, but still the second-highest figure the firm has seen.

"Ransomware is not new, but evidently its creators are making money from it, and that is the key to its persistence," observes Roger Thompson, chief emerging threat researcher at ICSA Labs. "In fact, it seems to have replaced fake antivirus as a common form of monetization. I can't remember the last time I saw a fake AV. You'd think that the interaction required to pass money would get more people caught, but I suspect it is a function of small amounts combined with multiple jurisdictions. In other words, it seems too much trouble for the police to be bothered."

The good news, Wisniewski notes, is that businesses and home users can take a number of precautions.

"Keep your antivirus up to date and be sure not to allow EXE files to come in as email attachments," he says. "Block EXE files inside of archives, like ZIP and RAR, at the mail gateway. CryptoLocker is primarily being installed through existing Zeus/ZBot infections, and Zeus comes in through email and drive-by installs on booby-trapped websites. Do your backups. Don't pay the crooks or depend on their honesty to decrypt your files. Ensure the important information in your organization is backed up regularly."

Have a comment on this story? Please click "Add Your Comment" below. If you'd like to contact Dark Reading's editors directly, send us a message. Brian Prince is a freelance writer for a number of IT security-focused publications. Prior to becoming a freelance reporter, he worked at eWEEK for five years covering not only security, but also a variety of other subjects in the tech industry. Before that, he worked as a ... View Full Bio

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
macker490
50%
50%
macker490,
User Rank: Ninja
11/24/2013 | 1:27:29 PM
re: CryptoLocker Could Herald Rise Of More Sophisticated Ransomware
a "CryptoLocker" hit should be treated as a hard drive fail. wipe the drive, re-install the os, and restore your data.

remember, cryptolocker will get all the active disks in your 'puter and goes after network shares as well. you will need an air-gap between your online system and your backup drive.
Register for Dark Reading Newsletters
White Papers
Cartoon
Current Issue
Video
Slideshows
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2012-3946
Published: 2014-04-24
Cisco IOS before 15.3(2)S allows remote attackers to bypass interface ACL restrictions in opportunistic circumstances by sending IPv6 packets in an unspecified scenario in which expected packet drops do not occur for "a small percentage" of the packets, aka Bug ID CSCty73682.

CVE-2012-5723
Published: 2014-04-24
Cisco ASR 1000 devices with software before 3.8S, when BDI routing is enabled, allow remote attackers to cause a denial of service (device reload) via crafted (1) broadcast or (2) multicast ICMP packets with fragmentation, aka Bug ID CSCub55948.

CVE-2013-6738
Published: 2014-04-24
Cross-site scripting (XSS) vulnerability in IBM SmartCloud Analytics Log Analysis 1.1 and 1.2 before 1.2.0.0-CSI-SCALA-IF0003 allows remote attackers to inject arbitrary web script or HTML via an invalid query parameter in a response from an OAuth authorization endpoint.

CVE-2014-0188
Published: 2014-04-24
The openshift-origin-broker in Red Hat OpenShift Enterprise 2.0.5, 1.2.7, and earlier does not properly handle authentication requests from the remote-user auth plugin, which allows remote attackers to bypass authentication and impersonate arbitrary users via the X-Remote-User header in a request to...

CVE-2014-2391
Published: 2014-04-24
The password recovery service in Open-Xchange AppSuite before 7.2.2-rev20, 7.4.1 before 7.4.1-rev11, and 7.4.2 before 7.4.2-rev13 makes an improper decision about the sensitivity of a string representing a previously used but currently invalid password, which allows remote attackers to obtain potent...

Best of the Web