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New Worm Leverages Open Source Tools and GitHub to Build its Botnet

New Worm Leverages Open Source Tools and GitHub to Build its Botnet

On September 19, 2018, Juniper Threat Labs discovered a new wave of attacks from a cryptominer worm targeting Linux servers, home networking devices, and IOT devices. These attacks were bundled with a number of exploits to spread rapidly and widely. The attack has three parts: infection, mining, and spreading.

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Juniper Employee
Mirai variant has Android devices in its crosshair

Mirai variant has Android devices in its crosshair

When the master learns from the student: following on Satori’s use of the misconfigured Android phones with a debug port enabled in shipping units, Juniper Threat Labs has identified a Mirai variant active in the wild, which for the first time is targeting the same channel to compromise misconfigured Android devices.

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Juniper Employee
The Gozi Sleeper Cell

The Gozi Sleeper Cell

Co-Authors:  Anoop Saldanha and  Paul Kimayong

  

Gozi, also known as Ursnif, is a well-known banking malware. Many variants of the malware family were identified in different attacks after its source code was leaked sometime back. Various instances of Gozi are still active. Criminals have modified the code and distributed it around the web. The sample was seen in one of our customer premises. Here is the hash of the sample.

 

IOCs

md5:8e29fa5f88ea28e36893f0b82b4d75e3,

sha1:220c38a509a2f0e62b279ad4f140e0aed79f2816

 

Attack Vector

Gozi is known to spread through spam emails with JavaScript attachments or Microsoft Office documents. Cisco Talos has referred to the spam campaigns in their blog: https://blog.talosintelligence.com/2018/03/gozi-isfb-remains-active-in-2018.html

 

The recent Gozi malware we discovered arrives downloaded by malicious Office files. These Office files are sent as attachments to spam, such as the example below:

 

 

email.pngspam email

 

 

 

 

'

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The Office document contains malicious macros and when enabled, it starts executing a PowerShell script to download the Ursnif binary.

 

 

 

javascript.pngjavascript attachment 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

In the past, Gozi also arrived via exploit kits.

Installation

When executed, Gozi drops a copy of itself in the %APPDATA%\{random}\{filename}.exe

In our sample, it drops as:

%APPDATA%\{random}\cicsapi.exe

 

Please note that the filename (cicsapi.exe) may vary per variant of Ursnif.

 

It also creates an autostart entry:

 

autostart.pngautostart entry 

 

 

 

Gozi’s main module is a DLL which is injected into explorer.exe

 

After successfully injecting to explorer.exe, the initial executable, cicsapi.exe, terminates. Variants may exhibit slightly different behavior.

 

Technical Details 

Gozi tries to evade analysis by manually “zeroing” out the PE header in memory. This behavior makes investigation more challenging due to the fact that most of the memory analysis tools usually check the PE header when inspecting a memory region.

zeroed PE header.pngzeroed PE Header 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Gozi itself has many anti-sandbox tricks, but this sample also has a trick embedded in the  covering packer layer. This is a sleep mechanism that has not been implemented directly by calling windows API sleep() but instead uses WaitforSingleObject() API with an invalid handle. This is to avoid sandbox detection.

 

waitForSingleObject() sleep.pngWaitForSingleObject() sleep

 The malware uses multi-level encryption. The malware unpacks by overwriting itself and upon unpacking, you can see a number of strings specific to the Gozi family.

 

Here is the unpacked file for the studied sample:

Md5:c6a85b251c197cbe25603468c8df9392

sha1:05afa48a229314b9cc3f785499799403e4f3076c

 

Here is a screenshot of the strings present in the unpacked file:

 

crmdllunpacked.pngfirst level unpacked strings

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

 

Gozi creates mailslot with the name “mailslot\ms10”, which is visible in the memory string. Mailslot is meant for interprocess communication, but Gozi tweaked the usage to make debugging harder.   Most of the time malware decrypt the code to memory buffer, but here it tries to write it to a mailslot. Standard debugging tools don’t provide a direct mechanism to look at what’s written to the mailslot.

 

The malware creates a mailslot using CreateMailslot API from one thread. In another thread, it gets handed to mailslot by using CreatFile API with a mailslot name as parameter. Then it writes the decoded buffer to mailslot.

 

 

mailslot.pngmailslot created

 mailslot2.pngwrite to mailslot

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

To see what is written into the mailslot, a reverser can change the file name in CreateFile from the mailslot to “C:\out”. Be sure that you manually create a file with that name as parameter to createFile is “OPEN_EXISTING”.

 

 

mailslot_write.pngReplace maislot name in createfile with a name

 

 

 

 

 

 

 

 

 

 

The WriteFile API writes the decoded content into the file “C:\out” and one can easily visualize it. We see that the partially decrypted DLL is written to the file. Looking into the strings, the DLL name seems to be crm.dll.

 

 

 crmpng.pngCRM.dll in memory

 

 

 

 

 

 

 

 

Hash for crm.dll

MD5:5afedfdd57b7ea0c03977a10f64fd2f4

SHA1:532ad626191e905010a0c00f3878927bcdfa0173

 

Crm.dll is responsible for further unpacking the payload into memory. But, this is not the final payload. It loads the actual Gozi payload further. The sample has various well-known anti-sandbox features like sleep delay. But, our deep memory inspection feature allows us to identify the payload in case the sample forbids us to execute completely. We can identify a lot of string in memory that has high resemblance to the leaked source code.

 

 

memory.pngMemory block showing URL

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

Below is a snapshot of one of the memory regions in the malware.If we search for the URL we can see a a number of GitHub forks.

github.pngMemory block showing URL 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The sample has additional interesting memory strings that show the pattern of CnC communication.

crmdllunpacked.pngCnC pattern in memory

 

 

 The sample connects to its C2 server:

  • Qf1q48wdq1dd[.]net

It communicates to its C2 server via SSL.

 

cnc.pngCnC communication via SSL  

 

 

 

 

 

 

 

 

 

There are other strings ie.. PR_Read that indicates that the malware tries to install a hook into browsers like Firefox in order to steal data.

 

firefox hook.pngstrings indicating firefox hook

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

These patterns can be used in intrusion detection signature and yara rules to identify the malware. The malware hooks API’s WSARecv, WSASend in order to intercept network communications.  

 

In addition to its malware, it also has the following capabilities:

  • Cookie theft
  • Email Credential theft
  • Log Browsing Activity
  • Keylogging

 

The stolen data is stored in the %temp% folder as a bin file with random 4-hexadecimal characters as filename, e.g, 676A.bin. It uses mscab.exe tool to archive the stolen data and sends this data to its C2 server.

 

stolen data stored.pngstolen data stored

 

 

 

 

 

 

 

 

 

 

 

 

 

 

stolen data transmitted.pngstolen data transmitted

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Detection

Both Juniper Sky ATP and JATP on-prem solutions detect this threat as seen in the screenshots below.  Keeping security solutions up-to-date can keep the customer protected against this threat.

 

cyphort.pngskyatp detection.png

 

Juniper Employee
VPNFilter: a global threat beyond routers

VPNFilter: a global threat beyond routers

When first publicly announced on May 23, the threat dubbed VPNFilter was thought to only infect some brands of home routers and Network Attached Storage devices. While it was known that the list of router brands was probably not complete, little did we know that the malware has the ability to infect the very computers sitting behind those routers and firewalls.

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VPNFilter: a nation state campaign for surveillance and destruction

VPNFilter: a nation state campaign for surveillance and destruction

  

VPNfilter is a campaign to compromise small office and home routers as well as Network Attached Storage devices from several popular manufacturers. According to a Cisco Talos blog, there are upward of 500,000 infected devices already and the list may not be exhaustive. The malware used has surveillance capabilities as well as destructive capabilities, including the ability to render the infected device unusable permanently.

 

ThinkstockPhotos-480182961_JNet.png

 

VPNfFilter has been lurking in the shadows for the better part of the last two years. It is unknown whether it uses any sophisticated means to breach internet connected devices, but the prevailing thinking in the security community is that it is exploiting previously known and unpatched vulnerabilities or just weak or default passwords. The malware is fairly sophisticated as it has multiple layers of redundancy in communicating with its command and control servers, using photo sharing site Photobucket, the specific hardcoded domain toknowall[.]com and a fallback plan of direct connection from the attackers to the compromised device itself. At some point in this fallback plan, it will open a socket connection and listen in on incoming packets looking for the specific packet from it's C2 server that will trigger an action.

 

As with any sophisticated implant, VPNfilter is capable of accepting a secondary payload that will perform most of the malware functions, but can also be augmented with purpose-built plugins. Two of the known plugins provide capability to sniff traffic looking for credentials or Modbus SCADA protocol and use TOR for communication. It is capable of doing anything a botnet can do, and more. The troubling part is its capability to wipe out a critical section of the infected device’s firmware rendering it permanently non functional, unless you are good with a soldering iron. If the threat actor behind this campaign pulls the trigger on this capability, hundreds of thousands of users will lose their connection to the internet until they purchase a new router.

 

There is evidence that the authors of this malware are the same as the authors of the BlackEnergy malware which crippled Ukraine’s energy grid in December 2015 and which the US Government attributed to Russian state actors. Additionally, Cisco observed on May 8 a heightened compromise activity focused on Ukrainian targets. Given that Ukraine’s Constitution Day on June 28 is fast approaching and given that Ukraine has suffered cyber attacks around this day in the past, there is circumstantial evidence that this build up is for an impending attack.

 

Call to action

 

Given the list of compromised device models is large and potentially incomplete, it is recommended that everyone reboot their home routers and NAS devices once. This will remove any second and third stage malware from their device since the malware does not have persistence capabilities. It will leave the first stage in place, which will try to download the second stage again, but with the law enforcement efforts to take down the known command and control infrastructure and the efforts by security vendors who provide equipment to Internet Service Providers, the threat should be partially mitigated. Additionally, make sure your device is patched to the latest firmware version released by the manufacturer, ensure default passwords are changed and disable any internet facing non necessary services, like remote management UI, SSH, Telnet, Ftp, etc.

 

Thanks to the Cyber Threat Alliance partnership that Juniper Networks is a member of, we have been able to put in place mitigation against all known actionable IOCs from this campaign.



Juniper Employee
Nukebot Banking Trojan targeting people in France

Nukebot Banking Trojan targeting people in France

Nukebot (aka TinyNuke, or NuclearBot) made the news in spring of 2017 when the author released the source code in an attempt to restore their/his/her reputation in the cybercrime .... According to IBM, a hacker calling himself “Gosya” tried to sell this malware in such a clumsy and inexperienced fashion that he managed to get himself banned from multiple cybercrime forums for violating specific rules about how such products should be soldA few weeks ago, Juniper Threat Labs started seeing an active attack involving this malware that specifically targets computers in France. The malware arrives as a ZIP file downloaded from malicious links. Inside the ZIP is an executable file that appears to be an installer built from the “Inno Setup” tool. When the malware executes, it drops a legitimate standalone version of Firefox browser in the %TEMP% and %APPDATA% that it uses to load a malicious dll. This dll is dropped in the same directory as firefox.exe, and then loaded by Firefox by taking advantage of a dll-sideloading attack affecting an old version of the browser. The dll checks if the system’s UI language or keyboard layout is French before conducting its malicious bidding.

 

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Latest Comments
threatresearch | 09-28-2018
Re: Kronos - The Banking Chronicle
threatresearch | 05-24-2018
Re: VPNFilter: a nation state campaign for surveillance and destruction
By  omarg
threatresearch | 02-20-2018
Re: Mobile Malware and Sky ATP