The ASEC analysis team is constantly monitoring malware distributed to vulnerable MS-SQL servers. The analysis team has recently discovered the distribution of FARGO ransomware that is targeting vulnerable MS-SQL servers. Along with GlobeImposter, FARGO is one of the prominent ransomware that targets vulnerable MS-SQL servers. In the past, it was also called the Mallox because it used the file extension .mallox.
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Figure 1. Process tree
As shown in the process tree in Figure 1, the file downloaded by the MS-SQL process through cmd.exe and powershell.exe is a file built on .Net (see Figure 2), downloads and loads additional malware from a particular address. The loaded malware generates and executes a BAT file which shuts down certain processes and services, in the %temp% directory.
Figure 2. Download of additional files
Figure 3. Creation and execution of BAT file
Figure 4. Details of BAT file
The ransomware’s behavior begins by being injected into AppLaunch.exe, a normal Windows program. It attempts to delete a registry key on a certain path (see Figure 5), and executes the recovery deactivation command, and closes certain processes (see Figure 6). As shown in the figures below, the closed processes are SQL programs.
Figure 5. Registry deletion
Figure 6. Deactivation of recovery and closing of processesWhen the ransomware encrypts files, files with file extensions shown in Table 1 are excluded from infection. The characteristic aspect is that it does not infect files with a file extension associated with Globeimposter and this exclusion list does not only include the same type of extensions of .FARGO .FARGO2 and .FARGO3 but also includes .FARGO4, which is thought to be a future version of the ransomware.
Table 1. Extensions excluded from infection
Table 2. Files excluded from infection
Table 3. Paths excluded from infection
Figure 7 shows a screen capture of the ransom note and the infected file on the top right in the same screen. As shown in the figure, the encrypted file gets a file name of OriginalFileName.FileExtension.Fargo3 and the ransom note is generated with the filename ‘RECOVERY FILES.txt’.
Figure 7. Ransom note and infected file
Typical attacks that target database servers (MS-SQL, MySQL servers) include brute force attacks and dictionary attacks on systems where account credentials are poorly being managed. And there may be vulnerability attacks on systems that do not have a vulnerability patch applied.
Administrators of MS-SQL servers should use passwords that are difficult to guess for their accounts and change them periodically to protect the database server from brute force attacks and dictionary attacks, and update to the latest patch to prevent vulnerability attacks.
AhnLab’s anti-malware software, V3, detects and blocks the malware using the following aliases:
[File Detection]
– Ransomware/Win.Ransom.C5153317(2022.06.02.01)
– Dropper/Win.DotNet.C5237010(2022.09.14.03)
– Downloader/Win.Agent.R519342(2022.09.15.03)
– Trojan/BAT.Disabler (2022.09.16.00)
Behavior Detection]
– Malware/MDP.Download.M1197
[IOC]
MD5
– b4fde4fb829dd69940a0368f44fca285
– c54daefe372efa4ee4b205502141d360
– 4d54af1bbf7357964db5d5be67523a7c
–41bcad545aaf08d4617c7241fe36267c
Download
– hxxp://49.235.255[.]219:8080/Pruloh_Matsifkq.png
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