Posts Tagged: Virustotal.com


9
Nov 15

Ransomware Now Gunning for Your Web Sites

One of the more common and destructive computer crimes to emerge over the past few years involves ransomware — malicious code that quietly scrambles all of the infected user’s documents and files with very strong encryption.  A ransom, to be paid in Bitcoin, is demanded in exchange for a key to unlock the files. Well, now it appears fraudsters are developing ransomware that does the same but for Web sites — essentially holding the site’s files, pages and images for ransom.

Image: Kaspersky Lab

Image: Kaspersky Lab

This latest criminal innovation, innocuously dubbed “Linux.Encoder.1” by Russian antivirus and security firm Dr.Web, targets sites powered by the Linux operating system. The file currently has almost zero detection when scrutinized by antivirus products at Virustotal.com, a free tool for scanning suspicious files against dozens of popular antivirus products.

Typically, the malware is injected into Web sites via known vulnerabilities in site plugins or third-party software — such as shopping cart programs. Once on a host machine, the malware will encrypt all of the files in the “home” directories on the system, as well backup directories and most of the system folders typically associated with Web site files, images, pages, code libraries and scripts.

The ransomware problem is costly, hugely disruptive, and growing. In June, the FBI said it received 992 CryptoWall-related complaints in the preceding year, with losses totaling more than $18 million. And that’s just from those victims who reported the crimes to the U.S. government; a huge percentage of cybercrimes never get reported at all.

ONE RECENT VICTIM

On Nov. 4, the Linux Website ramsomware infected a server used by professional Web site designer Daniel Macadar. The ransom message was inside a plain text file called “instructions to decrypt” that was included in every file directory with encrypted files:

“To obtain the private key and php script for this computer, which will automatically decrypt files, you need to pay 1 bitcoin(s) (~420 USD),” the warning read. “Without this key, you will never be able to get your original files back.”

Macadar said the malware struck a development Web server of his that also hosted Web sites for a couple of longtime friends. Macadar was behind on backing up the site and the server, and the attack had rendered those sites unusable. He said he had little choice but to pay the ransom. But it took him some time before he was able to figure out how to open and fund a Bitcoin account.

“I didn’t have any Bitcoins at that point, and I was never planning to do anything with Bitcoin in my life,” he said.

According to Macadar, the instructions worked as described, and about three hours later his server was fully decrypted. However, not everything worked the way it should have.

“There’s a  decryption script that puts the data back, but somehow it ate some characters in a few files, adding like a comma or an extra space or something to the files,” he said.

Macadar said he hired Thomas Raef — owner of Web site security service WeWatchYourWebsite.com — to help secure his server after the attack, and to figure out how the attackers got in. Raef told me his customer’s site was infected via an unpatched vulnerability in Magento, a shopping cart software that many Web sites use to handle ecommerce payments.

CheckPoint detailed this vulnerability back in April 2015 and Magento issued a fix yet many smaller ecommerce sites fall behind on critical updates for third-party applications like shopping cart software. Also, there are likely other exploits published recently that can expose a Linux host and any associated Web services to attackers and to site-based ransomware. Continue reading →


1
Sep 15

Like Kaspersky, Russian Antivirus Firm Dr.Web Tested Rivals

A recent Reuters story accusing Russian security firm Kaspersky Lab of faking malware to harm rivals prompted denials from the company’s eponymous chief executive — Eugene Kaspersky — who called the story “complete BS” and noted that his firm was a victim of such activity.  But according to interviews with the CEO of Dr.Web — Kaspersky’s main competitor in Russia — both companies experimented with ways to expose antivirus vendors who blindly accepted malware intelligence shared by rival firms.

quarantineThe Reuters piece cited anonymous, former Kaspersky employees who said the company assigned staff to reverse-engineer competitors’ virus detection software to figure out how to fool those products into flagging good files as malicious. Such errors, known in the industry as “false positives,” can be quite costly, disruptive and embarrassing for antivirus vendors and their customers.

Reuters cited an experiment that Kaspersky first publicized in 2010, in which a German computer magazine created ten harmless files and told antivirus scanning service Virustotal.com that Kaspersky detected them as malicious (Virustotal aggregates data on suspicious files and shares them with security companies). The story said the campaign targeted antivirus products sold or given away by AVG, Avast and Microsoft.

“Within a week and a half, all 10 files were declared dangerous by as many as 14 security companies that had blindly followed Kaspersky’s lead, according to a media presentation given by senior Kaspersky analyst Magnus Kalkuhl in Moscow in January 2010,” wrote Reuters’ Joe Menn. “When Kaspersky’s complaints did not lead to significant change, the former employees said, it stepped up the sabotage.”

Eugene Kaspersky posted a lengthy denial of the story on his personal blog, calling the story a “conflation of a number of facts with a generous amount of pure fiction.”  But according to Dr.Web CEO Boris Sharov, Kaspersky was not alone in probing which antivirus firms were merely aping the technology of competitors instead of developing their own.

Dr. Web CEO Boris Sharov.

Dr.Web CEO Boris Sharov.

In an interview with KrebsOnSecurity, Sharov said Dr.Web conducted similar analyses and reached similar conclusions, although he said the company never mislabeled samples submitted to testing labs.

“We did the same kind of thing,” Sharov said. “We went to the [antivirus] testing laboratories and said, ‘We are sending you clean files, but a little bit modified. Could you please check what your system says about that?'”

Sharov said the testing lab came back very quickly with an answer: Seven antivirus products detected the clean files as malicious.

“At this point, we were very confused, because our explanation was very clear: ‘We are sending you clean files. A little bit modified, but clean, harmless files,'” Sharov recalled of an experiment the company said it conducted over three years ago. “We then observed the evolution of these two files, and a week later, half of the antivirus products were flagging them as bad. But we never flagged these ourselves as bad.”

Sharov said the experiments by both Dr.Web and Kaspersky — although conducted differently and independently — were attempts to expose the reality that many antivirus products are simply following the leaders.

“The security industry in that case becomes bullshit, because people believe in those products and use them in their corporate environments without understanding that those products are just following others,” Sharov said. “It’s unacceptable.”

According to Sharov, a good antivirus product actually consists of two products: One that is sold to customers in a box and/or or online, and the second component that customers will never see — the back-end internal infrastructure of people, machines and databases that are constantly scanning incoming suspicious files and testing the overall product for quality assurance. Such systems, he said, include exhaustive “clean file” tests, which scan incoming samples to make sure they are not simply known, good files. Programs that have never been seen before are nearly always given more scrutiny, but they also are a frequent source of false positives.

“We have sometimes false positives because we are unable to gather all the clean files in the world,” Sharov said. “We know that we can get some part of them, but pretty sure we never get 100 percent. Anyway, this second part of the [antivirus product] should be much more powerful, to make sure what you release to public is not harmful or dangerous.”

Sharov said some antivirus firms (he declined to name which) have traditionally not invested in all of this technology and manpower, but have nevertheless gained top market share.

“For me it’s not clear that [Kaspersky Lab] would have deliberately attacked other antivirus firm, because you can’t attack a company in this way if they don’t have the infrastructure behind it,” Sharov said. Continue reading →


15
Jan 14

A First Look at the Target Intrusion, Malware

Last weekend, Target finally disclosed at least one cause of the massive data breach that exposed personal and financial information on more than 110 million customers: Malicious software that infected point-of-sale systems at Target checkout counters. Today’s post includes new information about the malware apparently used in the attack, according to two sources with knowledge of the matter.

The seller of the point-of-sale "memory dump" malware used in the Target attack.

The seller of the point-of-sale “memory dump” malware allegedly used in the Target attack.

In an interview with CNBC on Jan. 12, Target CEO Gregg Steinhafel confirmed that the attackers stole card data by installing malicious software on point-of-sale (POS) devices in the checkout lines at Target stores. A report published by Reuters that same day stated that the Target breach involved memory-scraping malware.

This type of malicious software uses a technique that parses data stored briefly in the memory banks of specific POS devices; in doing so, the malware captures the data stored on the card’s magnetic stripe in the instant after it has been swiped at the terminal and is still in the system’s memory. Armed with this information, thieves can create cloned copies of the cards and use them to shop in stores for high-priced merchandise. Earlier this month, U.S. Cert issued a detailed analysis of several common memory scraping malware variants.

Target hasn’t officially released details about the POS malware involved, nor has it said exactly how the bad guys broke into their network. Since the breach, however, at least two sources with knowledge of the ongoing investigation have independently shared information about the point-of-sale malware and some of the methods allegedly used in the attack.

‘BLACK POS’

On Dec. 18, three days after Target became aware of the breach and the same day this blog broke the story, someone uploaded a copy of the point-of-sale malware used in the Target breach to ThreatExpert.com, a malware scanning service owned by security firm Symantec. The report generated by that scan was very recently removed, but it remains available via Google cache (Update, Jan. 16, 9:29 a.m.: Sometime after this story ran, Google removed the cached ThreatExpert report; I’ve uploaded a PDF version of it here).

According to sources, "ttcopscli3acs" is the name of the Windows share point used by the POS malware planted at Target stores; the username that the thieves used to log in remotely and download stolen card data was "Best1_user"; the password was "BackupU$r"

According to sources, “ttcopscli3acs” is the name of the Windows computer name/domain used by the POS malware planted at Target stores; the username that the malware used to upload stolen data data was “Best1_user”; the password was “BackupU$r”

According to a source close to the investigation, that threatexpert.com report is related to the malware analyzed at this Symantec writeup (also published Dec. 18) for a point-of-sale malware strain that Symantec calls “Reedum” (note the Windows service name of the malicious process is the same as the ThreatExpert analysis –“POSWDS”). Interestingly, a search in Virustotal.com — a Google-owned malware scanning service — for the term “reedum” suggests that this malware has been used in previous intrusions dating back to at least June 2013; in the screen shot below left, we can see a notation added to that virustotal submission, “30503 POS malware from FBI”.

The source close to the Target investigation said that at the time this POS malware was installed in Target’s environment (sometime prior to Nov. 27, 2013), none of the 40-plus commercial antivirus tools used to scan malware at virustotal.com flagged the POS malware (or any related hacking tools that were used in the intrusion) as malicious. “They were customized to avoid detection and for use in specific environments,” the source said.

pos-fbiThat source and one other involved in the investigation who also asked not to be named said the POS malware appears to be nearly identical to a piece of code sold on cybercrime forums called BlackPOS, a relatively crude but effective crimeware product. BlackPOS is a specialized piece of malware designed to be installed on POS devices and record all data from credit and debit cards swiped through the infected system.

According the author of BlackPOS — an individual who uses a variety of nicknames, including “Antikiller” — the POS malware is roughly 207 kilobytes in size and is designed to bypass firewall software. The barebones “budget version” of the crimeware costs $1,800, while a more feature-rich “full version” — including options for encrypting stolen data, for example — runs $2,300.

Continue reading →


18
Jul 13

Botcoin: Bitcoin Mining by Botnet

An increasing number of malware samples in the wild are using host systems to secretly mine bitcoins. In this post, I’ll look at an affiliate program that pays people for the mass installation of programs that turns host machines into bitcoin mining bots.

The FeodalCash bitcoin mining affiliate program.

The FeodalCash bitcoin mining affiliate program.

Bitcoin is a decentralized, virtual currency, and bitcoins are created by large numbers of CPU-intensive cryptographic calculations. As Wikipedia explains, the processing of Bitcoin transactions is secured by servers called bitcoin miners. These servers communicate over an internet-based network and confirm transactions by adding them to a ledger which is updated and archived periodically using peer-to-peerfilesharing technology. In addition to archiving transactions, each new ledger update creates some newly minted bitcoins.

Earlier this week, I learned of a Russian-language affiliate program called FeodalCash which pays its members to distribute a bitcoin mining bot that forces host PCs to process bitcoin transactions (hat tip to security researcher Xylitol). FeodalCash opened its doors in May 2013, and has been recruiting new members who can demonstrate that they have control over enough Internet traffic to guarantee at least several hundred installs of the bitcoin mining malware each day.

The FeodalCash administrator claims his mining program isn’t malware, although he cautions all affiliates against submitting the installer program to multi-antivirus scanners such as Virustotal; sending the program that installs bitcoin mining bot to Virustotal “greatly complicates the work with antivirus” on host PCs. Translation: Because services like Virustotal share information about new malware samples with all participating antivirus vendors, scanning the installer will make it more likely that antivirus products on host PCs will flag the program as malicious. Rather, the administrator urged users who want to check the files for antivirus detection to use a criminal friendly service like scan4u[dot]net or chk4me[dot]com, which likewise scan submitted files with dozens of different antivirus tools but block those tools from reporting home about new and unidentified malware variants.

This Google-translated version of the site shows the builder for the installer.

This Google-translated version of the site shows the builder for the installer.

I gained access to an affiliate account and was able to grab a copy of the mining program. I promptly submitted the file to Virustotal and found it was flagged as a trojan horse program by at least two antivirus products. This analysis at automated malware scanning site malwr.com shows that the mining program installer ads a Windows registry key so that the miner starts each time Windows boots up. It also indicates that the program beacons out to pastebin.com (perhaps to deposit a note about each new installation).

The FeodalCash administrator also claims that his affiliates are not permitted to distribute the installer file in any way that violates the law, but of course it’s unclear which national laws he might be talking about. At the same time, the affiliate program’s Web site includes a graphical tool that helps affiliates create a custom installer program that can install silently and be disguised with a variety of program icons that are similar to familiar Windows icons.

Also, the administrator demands that new users demonstrate the ability to garner hundreds to thousands of installs per day. This is a rather high install rate, and it appears many if not all affiliates are installing the mining program by bundling it with other executable programs distributed by so-called pay-per-install (PPI) programs. This was apparent because a source managed to gain administrative-level access to the back-end database for the FeodalCash program, which includes hundreds of messages between affiliates and the administrator; most of those messages are from new registrants sending the administrator screenshots  of their traffic and installs statistics at various PPI affiliate programs.

Continue reading →


31
Jul 12

Email-Based Malware Attacks, July 2012

Last month’s post examining the top email-based malware attacks received so much attention and provocative feedback that I thought it was worth revisiting. I assembled it because victims of cyberheists rarely discover or disclose how they got infected with the Trojan that helped thieves siphon their money, and I wanted to test conventional wisdom about the source of these attacks.

Top malware attacks and their antivirus detection rates, past 30 days. Source: UAB

While the data from the past month again shows why that wisdom remains conventional, I believe the subject is worth periodically revisiting because it serves as a reminder that these attacks can be stealthier than they appear at first glance.

The threat data draws from daily reports compiled by the computer forensics and security management students at the University of Alabama at Birmingham. The UAB reports track the top email-based threats from each day, and include information about the spoofed brand or lure, the method of delivering the malware, and links to Virustotal.com, which show the number of antivirus products that detected the malware as hostile (virustotal.com scans any submitted file or link using about 40 different antivirus and security tools, and then provides a report showing each tool’s opinion).

As the chart I compiled above indicates, attackers are switching the lure or spoofed brand quite often, but popular choices include such household names as American Airlines, Ameritrade, Craigslist, Facebook, FedEx, Hewlett-Packard (HP), Kraft, UPS and Xerox. In most of the emails, the senders spoofed the brand name in the “from:” field, and used embedded images stolen from the brands being spoofed.

The one detail most readers will probably focus on most this report is the atrociously low detection rate for these spammed malware samples. On average, antivirus software detected these threats about 22 percent of the time on the first day they were sent and scanned at virustotal.com. If we take the median score, the detection rate falls to just 17 percent. That’s actually down from last month’s average and median detection rates, 24.47 percent and 19 percent, respectively.

Continue reading →


5
Jul 12

New Java Exploit to Debut in BlackHole Exploit Kits

Malicious computer code that leverages a newly-patched security flaw in Oracle’s Java software is set to be deployed later this week to cybercriminal operations powered by the BlackHole exploit pack. The addition of a new weapon to this malware arsenal will almost certainly lead to a spike in compromised PCs, as more than 3 billion devices run Java and many of these installations are months out of date.

I first learned about the new exploit from a KrebsOnSecurity reader named Dean who works in incident response for a financial firm. Dean was trying to trace the source of an infected computer in his network; he discovered the culprit appeared to be a malicious “.jar” file. A scan of the jar file at Virustotal.com showed that it was detected by just one antivirus product (Avira), which flagged it as “Java/Dldr.Lamar.BD”. The description of that threat says it targets a Javas vulnerability tagged as CVE-2012-1723, a critical bug fixed in Java 6 Update 33 and Java 7 Update 5.

The attack may be related to an exploit published for CVE-2012-1723 in mid-June by Michael ‘mihi’ Schierl. But according to the current vendor of the BlackHole exploit pack, the exact exploit for this vulnerability has only been shared and used privately to date. Reached via instant message, the BlackHole author said the new Java attack will be rolled into a software update to be made available on July 8 to all paying and licensed users of BlackHole.

Continue reading →


21
Jun 12

A Closer Look: Email-Based Malware Attacks

Nearly every time I write about a small- to mid-sized business that has lost hundreds of thousands of dollars after falling victim to a malicious software attack, readers want to know how the perpetrators broke through the victim organization’s defenses, and which type of malware paved the way. Normally, victim companies don’t know or disclose that information, so to get a better idea, I’ve put together a profile of the top email-based malware attacks for each day over the past month.

Top malware email attacks in past 30 days. Source: UAB

This data draws from daily reports compiled by the computer forensics and security management students at the University of Alabama at Birmingham, a school I visited last week to give a guest lecture and to gather reporting for a bigger project I’m chasing. The UAB reports track the top email-based threats from each day, and include information about the spoofed brand or lure, the method of delivering the malware, and links to Virustotal.com, which show the percentage of antivirus products that detected the malware as hostile.

As the chart I compiled above indicates, attackers are switching the lure or spoofed brand quite often, but popular choices include Amazon.com, the Better Business Bureau, DHL, Facebook, LinkedIn, PayPal, Twitter and Verizon Wireless.

Also noticeable is the lack of antivirus detection on most of these password stealing and remote control Trojans. The average detection rate for these samples was 24.47 percent, while the median detection rate was just 19 percent. This means that if you click a malicious link or open an attachment in one of these emails, there is less than a one-in-five chance your antivirus software will detect it as bad.

Continue reading →


27
Oct 11

Chasing APT: Persistence Pays Off

The IT director for an international hedge fund received the bad news in a phone call from a stranger: Chinese hackers were running amok on the fund’s network. Not seeing evidence of the claimed intrusion, and unsure about the credibility of the caller, the IT director fired off an email to a reporter.

“So do you think this is legit, or is the guy trying to scare us?” the IT director asked in an email to KrebsOnSecurity.com, agreeing to discuss the incident if he and his company were not named. “He has sent me the logs for the connections to the infected server. I checked the firewall and am not seeing any active connections.”

The call, from Hermes Bojaxhi of Columbia, Md. based threat intelligence firm Cyber Engineering Services Inc. (CyberESI), was indeed legit, and a follow-up investigation by the hedge fund revealed that at least 15 PCs within the financial services company were compromised and were sending proprietary information to the attackers.

CyberESI knew about the incident because it was monitoring several hacked, legitimate servers that the attackers were using to siphon data from multiple victims. Bojaxhi said the hedge fund notification was one of several he made that week to Fortune 500 companies that also had been hacked and were communicating with the same compromised servers.

And it wasn’t his first call to the hedge fund.

“On that particular victim, I tried to reach out to them a month prior, but I was handed off to an administrative assistant,” Bojaxhi said. “We had 25 [victim organizations] to call that day. But when they popped back up on the radar a month later, I tried again.”

The hedge fund incident illustrates the complexities of defending against and detecting targeted attacks, even when victims are alerted to the problem by an outside party.

Joe Drissel, founder and CEO for CyberESI, said too many companies think of cyberattacks as automated threats that can be blocked with the proper mix of hardware and software.

“So many firms are stuck in a paradigm of drive-bys, not targeted attacks,” Drissel said. “There seems to be a real disconnect with what’s really happening on a daily basis. We’re trying to fight an asymmetrical war in a symmetrical way, sort of like we’re British soldiers [in Revolutionary War], all walking in line and they’re picking us off one by one. By the time we turn around and aim, they’re already gone.”

None of the first three Trojans installed on the hedge fund’s computers were initially detected by any of the 42 anti-virus products bundled into the scanning tools at Virustotal.com.

Drissel said victims that his company notifies sometimes mistakenly think his firm is involved in the attack, or that they’re somehow joking.

“One guy laughed and said, ‘Thank you for watching out for our company,’ but he didn’t call us back,” Drissel said of a conversation with a victim earlier this year, declining to name the victim. “We watched [the attackers] exfiltrate weapons systems data for the Defense Department out of their systems, and ended up having to text the same guy a file stolen off their servers. Fifteen minutes later, we got a call back from him, and they unplugged their entire corporate network.”

Some say that the attacks CyberESI notifies companies about — often referred to as the advanced persistent threat (APT) —  are over-hyped, and that the malware and exploits used in these incursions usually aren’t that sophisticated. APT attacks also are frequently associated with targets in the U.S. government and companies in the defense industry.

But most APT attackers tend to be only as sophisticated as they need to be, which often isn’t too sophisticated, said Gavin Reid, senior manager of Cisco’s computer security incident response team. Speaking at a conference in Warsaw, Poland this week, Reid said successful APT attacks need not use zero-day software flaws.

“People will say, ‘Well, this attack wasn’t very advanced, so it can’t be APT’, but I will tell you the folks who are behind some of this stuff are not going to use cool zero-day stuff if they can go in the underground economy and say, ‘Hey, I need [access to] an infected machine in this organization,’ and pay $50 in Paypal in order to get that,” Reid said.

Continue reading →