Smoke Loader

The main function of Smoke Loader is dropping other, more destructive malware on infected machines. However, unlike many competing loaders, this one can be extended via plugins to feature destructive, malicious info-stealing functions.

Type
Loader
Origin
ex-USSR territory
First seen
30 August, 2011
Last seen
19 May, 2022
Also known as
Dofoil
Global rank
26
Week rank
19
Month rank
23
IOCs
19619

What is Smoke Loader?

Smoke Loader, sometimes also called Dofoil, is a modular malware mainly utilized to download other viruses to infected machines. Despite its loader nature, the Smoke Loader bot can be equipped with a variety of malicious functions. Most of these functions are targeted at stealing sensitive data from the victims.

Smoke Loader was first observed in the wild in 2011. It was seen being sold on underground portals grabberz[.]com and xaker[.]name by a member named SmokeLdr. The malware functionality varies from one attack to the other and depends on the choice of modules done by the attackers.

Despite its old age, Smoke Loader continues to be an active threat even to this day. In particular, this malware was featured in RigEK and MalSpam campaigns. It should be noted that after March 2014, Smoke Loader is sold only to Russian-speaking attackers.

General description of Smoke Loader

The main functions of Smoke Loader include loading up to ten executable files and run them, geo-target the victims to direct attacks at specific countries, load files via URLs, mimic legitimate processes, and provide detailed summaries on installs and launches.

The two optional modules allow Smoke Loader to expand its feature set with information-stealing functions. This allows Dofoil to grab passwords from widely used mail clients, FTP clients, and programs like TeamViewer. The malware can send the data to the C2 for the attacker.

The Smoke Loader virus has been evolving over the years. According to the research of a cybersecurity professional, a late 2018 sample included an array of anti-debugging techniques far more complex than anything present in the early iterations of the malware. For instance, the 2018 Smoke Loader version learned to check if it is being launched in the virtual environment. It also learned to discover and immediately kill any analyzing tools running on the machine. Together, these features make the analysis of the Dofoil malware highly complicated. Dofoil also relies a lot on the process hollowing technique, targeting mostly Explorer.exe.

What’s more, while a lot of malware in the wild need to iterate through a list of processes to find their injection target, thus allowing researchers to discover them, Smoke Loader manages to avoid this behavior and stay hidden by calling the Windows API GetShellWindow to access the shell’s desktop window, and evoke GetWindowThreadProcessId to obtain the process ID of Explorer.exe.

To further confuse security researchers, all Smoke Loader functions contain pointless instructions. At the same time, the library names are encrypted with a hardcoded key. Instructions are not coded in a standard way. Instead, they are mixed with jump instructions. Most of this code reroutes the program flow to create confusion when Dofoil is debugged.

Malware analysis of Smoke Loader

A video recorded in the ANY.RUN malware hunting service displays the execution process of Smoke Loader. It allows examining the malware in a convenient and safe environment.

smokeloader execution process graph

Figure 1: Displays the graph of processes generated by the ANY.RUN malware analyzing service

text report of the smokeloader malware analysis

Figure 2: Even more information about the execution of malware can be found in customizable text reports generated by ANY.RUN

Smoke Loader execution process

So, how does Smoke Loader work? Because the most common vector of attack to infect users' devices are malicious spam campaigns, Smoke Loader trojan mostly gets into devices with Microsoft Office files. Once the user downloads and opens the malicious file, the malware drops to a machine from it.

After that, SmokeLoader injects malicious code into system processes like explorer.exe. An injected process then starts the main malicious activity.

Distribution of Smoke Loader

The smoke Loader virus makes its way to machines as a malicious Microsoft Word attachment. It is initially delivered to users in spam email campaigns. Attackers use social engineering to trick potential victims into downloading the attached file and enabling the macros, the same scenario is applied by Ave Maria and Revenge.

This makes contamination prevention fairly simple. Users are advised to stay clear of downloading files from suspicious emails and keep macros disabled. And especially, never enable them if prompted by a downloaded file.

How Smoke Loader communicates with C&C?

Smoke Loader malware tries to hide its malicious nature. This is done by mixing infrequent requests to legitimate websites into C&C communication. The virus connects to websites such as Microsoft.com and Adobe.com. Despite receiving mainly HTTP 404 in requests, data is still evident in the response body.

How to detect Smoke Loader using ANY.RUN?

Since SmokeLoader almost always infects systems using similar attack vectors, it can be identified using its execution process. After the executable file, which contains Smoke Loader, has been delivered in the system and launched, it injects its code into the system process like "explorer.exe."

This means that if, after some time following the execution of a sample, an "explorer.exe" process appears, it is time to look into it. To do so, click on the process in the "Process list" section, and in the appeared "Process details" window click the "More info" button. If in the event section you see that previously injected "explorer.exe" create a file named "tesrdgeh.exe," it is a clear indication that you are dealing with Smoke Loader trojan.

SmokeLoader created a file Figure 3: Injected explorer.exe created file tesrdgeh.exe

Summary

Despite being rather old, the Dofoil virus is only gaining popularity. Since its first surfacing in 2011, the malware remains a highly active and elusive threat, not due to its advanced anti-evasion functions. In addition to being used as a loader and installing potentially more dangerous malware.

What’s more, Smoke Loader itself can be used to pull sensitive information from infected machines and conduct destructive, malicious campaigns.

Thankfully, advanced malware hunting services such as ANY.RUN allows us to bypass some of the anti-evasion tricks implemented by the Smoke Loader creators and successfully conduct the analysis of this virus.

IOCs

IP addresses
92.123.225.67
34.102.136.180
104.89.38.104
2.21.20.204
104.102.28.152
210.92.250.133
211.229.47.232
115.88.24.203
208.91.197.91
116.121.62.237
180.69.193.102
211.59.14.90
23.202.231.167
104.111.242.51
92.123.194.170
184.24.77.52
209.99.40.222
92.123.225.73
208.100.26.245
37.140.192.62
Hashes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cloudflare.hcaptcha.com
madbbs.org
id.a-mx.com
cdn.usefulcontentsites.com
ugll.org
zerit.top
bahninfo.at
colgefine.at
hanfinvest.at
gerer.at
linislominyt11.at
recmaster.ru
fuyt.org
lencu.top
www.lockbitapt.uz
lockbitapt.uz
rcacademy.at
tisaur33.top
tisnay23.top
fraudlabpros.at

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