HoeflerText Popups Targeting Google Chrome Users

Researchers spotted a new EITest campaign leveraging HoeflerText Popups to target Google Chrome users and push NetSupport Manager RAT or Locky ransomware.

Security researchers with both the SANS Internet Storm Center and Palo Alto Networks’ Unit 42, has spotted a malware campaign leveraging bogus popups that alert users to a missing web-font.

The attackers are targeting Google Chrome and Firefox browser users, the researcher discovered the popups contain a malicious JavaScript file that delivers either the NetSupport Manager remote access tool (RAT) or Locky ransomware.

Many similarities with the EITest malware campaign have been discovered.

“The attackers behind the EITest campaign have occasionally implemented a social engineering scheme using fake HoeflerText popups to distribute malware targeting users of Google’s Chrome browser. In recent months, the malware used in the EITest campaign has been ransomware such as Spora and Mole.” reads the post published by PaloAlto Networks. “However, by late August 2017, this campaign began pushing a different type of malware.  Recent samples are shown to infect Windows hosts with the NetSupport Manager remote access tool (RAT). This is significant, because it indicates a potential shift in the motives of this adversary.”

Victims are lured to a compromised website that generates a bogus popup message informing the user the webpage they are trying to view cannot display correctly because their browser hasn’t the correct “HoeflerText” font and suggest them to fix the issue downloading a Chrome Font Pack.

Hoefler-campaign-malware

However, when the same links were tried in Google Chrome, they displayed a fake notification stating: The “HoeflerText” font was not found.

These notifications also had an ‘update’ button. When they were clicked , a JavaScript file named Win.JSFontlib09.js was recieved. That JavaScript file is designed to download and install Locky ransomware.

In another case, the same Chrome HoeflerText font update delivers the file “Font_Chrome.exe” file that delivers and installs NetSupport Manager RAT.

The expert tried different browsers and observed mixed behaviors, Tor and Yandex browsers both returned the same results as IE 11 and Microsoft Edge when viewing those fake Dropbox pages.  Opera and Vivaldi returned the same HoeflerText notifications seen in Google Chrome.

Victims using Internet Explorer or Microsoft Edge on bogus webpages did not trigger the HoeflerText’ popup,  rather, victims will get a fake anti-virus alert with a phone number for a tech support scam.

“Users should be aware of this ongoing threat. Be suspicious of popup messages in Google Chrome that state: The ‘HoeflerText’ font wasn’t found. Since this is a RAT, infected users will probably not notice any change in their day-to-day computer use. If the NetSupport Manager RAT is found on your Windows host, it is probably related to a malware infection,” post concluded.

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Education & Healthcare industries targeted by Defray Ransomware

A new ransomware has been discovered by researchers of Proofpoint used in targeting Education & healthcare organisations.

The ransomware used in the campaign was dubbed Defray, based on the command and control (C&C) server hostname used for the first observed attack:

defrayable-listings[.]000webhostapp[.]com

The ransomware is being spread via Microsoft Word document attachments in email.

The researchers observed two targeted attack on Aug. 15, and on Aug. 22, and both appeared to be designed for specific organizations.

The attack on August 15 targeted Manufacturing and Technology verticals, attackers used messages with the subject “Order/Quote” and a Microsoft Word document containing an embedded executable (also an OLE packager shell object).

defrayf1
The Word document, patient_report.doc, delivered in malicious email messages

The attack on August 22, aimed primarily at Healthcare and Education involving messages with a Microsoft Word document containing an embedded executable (specifically, an OLE packager shell object). The attachment features a UK hospital logo in the upper right and purports to be from the Director of Information Management & Technology at the hospital.

defrayf2
Word document attachment, presentation.doc, delivered in malicious email messages

If the potential victim double clicks on the embedded executable, the ransomware is dropped with a name such as taskmgr.exe or explorer.exe in the %TMP% folder and executed.

The ransomware contains a hardcoded list of file extensions, shown below, for files that it will encrypt (although we observed others such as .lnk and .exe encrypted that were not on this list). The file extensions of modified files were not changed. We observed that the modified files all end in bytes “30 82 04 A4 02 01 00 02 82 01 01 00 9F CF 52 84” for our sample.

Defray has been observed communicating with an external C&C server via both HTTP (clear-text, shown in Figure 4) and HTTPS, to which it will report infection information.

After encryption is complete, Defray may cause other general havoc on the system by disabling startup recovery and deleting volume shadow copies. On Windows 7 the ransomware monitors and kills running programs with a GUI, such as the task manager and browsers.

“Defray Ransomware is somewhat unusual in its use in small, targeted attacks. Although we are beginning to see a trend of more frequent targeting in ransomware attacks, it still remains less common than large-scale “spray and pray” campaigns. It is also likely that Defray is not for sale, either as a service or as a licensed application like many ransomware strains. Instead, it appears that Defray may be for the personal use of specific threat actors, making its continued distribution in small, targeted attacks more likely” concluded Proofpoint.

 

Mamba ransomware is back, hitting organizations in Brazil and Saudi Arabia

Mamba was among the first samples of ransomware that encrypted hard drives rather than files that was detected in public attacks.Mamba leverages a disk-level encryption strategy instead of the conventional file-based one.

The first sample of Mamba Ransomware discovered in the wild were using a full disk encryption open source tool called DiskCryptor to strongly encrypt the data.

Researchers at Kaspersky Lab discovered a new wave of attack leveraging the Mamba ransomware that hit organizations in Brazil and Saudi Arabia.

“Authors of wiper malware are not able to decrypt victims’ machines. For example, if you remember the ExPetr [malware], it uses a randomly generated key to encrypt a victim machine, but the trojan doesn’t save the key for further decryption,” said Kaspersky Lab researcher Orkhan Memedov. “So, we have a reason to call it ‘a wiper.’ However, in case of Mamba the key should be passed to the trojan as a command line argument, it means that the criminal knows this key and, in theory, the criminal is able to decrypt the machine.”

Once the malware has infected a Windows machine, it overwrites the existing Master Boot Record, with a custom MBR and encrypts the hard drive using the DiskCryptor tool.

“Unfortunately there is no way to decrypt data that has been encrypted with the DiskCryptor utility, because this legitimate utility uses strong encryption algorithms,” explained Kaspersky Lab.

The last samples of Mamba ransomware show an unusual ransom note that instead of demanding for money like the original Mamba, it provides two email addresses and an ID number to be used to recover the encryption key.

The threat actor behind the new wave of Mamba ransomware attacks leverages the PSEXEC utility to execute the malware on the corporate network once it has penetrated it. PSEXEC is the same tool used by NotPetya to spread within target networks.

The attack chain described by Kaspersky has two phases:

Stage 1 (Preparation):

  • Create folder “C:\xampp\http
  • Drop DiskCryptor components into the folder
  • Install DiskCryptor driver
  • Register system service called DefragmentService
  • Reboot victim machine

Stage 2 (Encryption):

  • Setup bootloader to MBR and encrypt disk partitions using DiskCryptor software
  • Clean up
  • Reboot victim machine

The complete technical analysis can be found here.

“It is important to mention that for each machine in a victim’s network, the threat actor generates a password for the DiskCryptor utility,” Kaspersky Lab said in its report. “This password is passed via command line arguments to the ransomware dropper.”

Petya Ransomware hits the Globe

petya-ransomware-attack-1

On 27 June a nasty piece of ransomware (now declared as a wiper malware) struck the globe within the 2 months of previous ransomware outbreak i.e. WannaCry. The Petya ransomware(now Known as NotPetya Malware) attacks that began infecting computers in several countries, including Russia, Ukraine, France, India and the United States on Tuesday and demands $300 ransom was not designed with the intention of restoring the computers at all. The virus was designed to look like ransomware but was wiper malware that wipes computers outright, destroying all records from the targeted systems. The Email id used to receive the payments in Bitcoin has been shut down so even though the ransom is paid files will not be recovered.

Similar to WannaCry, Petya uses the Eternal Blue exploit as one of the means to propagate itself. However it also uses classic SMB network spreading techniques, meaning that it can spread within organizations, even if they’ve patched against Eternal Blue.

It has been confirmed that MEDoc, a tax and accounting software package, is used for the initial insertion of Petya into corporate networks. MEDoc is widely used in Ukraine, indicating that organizations in that country were the primary target.

After gaining an initial foothold, Petya then uses a variety of methods to spread across corporate networks.

What makes it dangerous? Unlike other ransomware viruses, it encrypts the Master File Table (MFT) for NTFS partitions. Each file on an NTFS volume is represented by a record in a special file called the master file table (MFT). If the MFT is corrupted the file system structure on the disk becomes unusable. It also overwrites MBR (Master Boot Record) with a custom bootloader that shows a ransom note and prevents the victim from booting their computer. This means that once a machine is infected it is in a complete state of lockdown. This makes it more intrusive. In comparison, the WannaCry ransomware virus targeted only specific file extensions while still allowing the operating system access.

INFECTION AND INSTALLATION

According to Symantec , Petya is initially executed via rundll32.exe using the following command:

  • rundll32.exe perfc.dat

Once the DLL has been loaded, it will first attempt to remove itself from the infected system. This is done by opening the file and overwriting its contents with null bytes before finally deleting the file from disk. Overwriting the file with null bytes is used as an attempt to thwart recovery of the file using forensic techniques.

Next, it attempts to create the following file to be used as a flag indicating that the computer has been infected:

  • C:\Windows\perfc

Once installed, Petya proceeds to modify the master boot record (MBR). This allows it to hijack the normal loading process of the infected computer during the next system reboot. The modified MBR is used to encrypt the hard disk while simulating a CHKDSK screen. It then displays a ransom note to the user.

MBR modification does not succeed if the threat is executed as a normal user but the threat will still attempt to spread across the network

At this point, a system reboot is scheduled using the following command:

  • “/c at 00:49 C:\Windows\system32\shutdown.exe /r /f”

By scheduling and not forcing a reboot, it provides time to allow Petya to spread to other computers in the network before user-mode encryption occurs.

Once Petya does get into a local network, however, there are several concurrent mechanisms for it to spread to further local machines. The first and foremost is the ETERNALBLUE exploit. The next mechanism is to use mimikatz to dump credentials and use said credentials to run itself in local LAN computers using either PsExec or wmic.exe.

The following 4 steps are followed by the malware to spread itself:

  1. Tries to find credentials:
    • Method 1: Uses a custom tool to extract credentials from memory (code similarities with MimiKatz and accesses Windows LSASS process)
    • Method 2: Steals credentials from the credential store on the infected systems
  2. Makes an inventory of the local network for other machines. If found, it checks whether port 139 or 445 is open
  3. Checks via WebDAV whether the enumerated systems have already been infected. If this is not the case, it will transfer the malware to the other systems via SMB;
  4. Utilizes PSEXEC or WMI tools, to remotely execute the malware.

Once spreading has occurred, Petya then lists all files on any fixed drive (e.g. C:\) and checks for any of the following file extensions (skipping the %Windir% directory of that drive):

.3ds .7z .accdb .ai .asp .aspx .avhd .back .bak .c .cfg .conf .cpp .cs .ctl .dbf .disk .djvu .doc .docx .dwg .eml .fdb .gz .h. hdd .kdbx .mail .mdb .msg .nrg .ora .ost .ova .ovf .pdf .php .pmf .ppt .pptx .pst .pvi .py .pyc .rar .rtf .sln .sql .tar .vbox .vbs .vcb .vdi .vfd .vmc .vmdk .vmsd .vmx .vsdx .vsv .work .xls .xlsx .xvd .zip

An AES 128 bit key is generated for each drive. If any of the file extensions match that of the above list, the malware proceeds to encrypt the first 1MB of the file using the generated key.

After encrypting all eligible files, the threat will generate the ransom note and write it to a “README.TXT” file in the current drive.

The generated AES key(s) then encrypts itself using an embedded public key.

The resulting encrypted blob is then appended to the end of the ransom note (README.TXT) as a Base64 encoded string. The ransom note refers to this as the “installation key”.

The generated key is then destroyed to ensure it cannot be retrieved from memory.

At this point, the system is rebooted and the modified MBR code loads the simulated CHKDSK screen and full disk encryption occurs.

PREVENTION 

Checking if you are at risk for this attack involves multiple actions, due to the fact that the attack itself uses different methods to propagate within networks. The following actions can be performed to identify potential vulnerable machines within the network:

  • Perform a network portscan to identify systems on which the TCP ports 139 and 445 are open. The more machines that are accessible on these ports, the more potential risk of the attack spreading to large amounts of systems within the network.
  • Perform a vulnerability scan to identify machines which are missing the MS17-010 (and the KB2871997) patch. If the patches are missing, the identified systems are vulnerable to the one of the spreading and infection methods used by the malware.
  • Create a file perfc. C:\Windows\perfc beforehand.