Bisonal

o Dissemination strategy: via Dropper or email attachment

The most common is infection via spear phishing email, where an email containing an infecting document is sent to a targeted email address.

%TEMP% 경로에 생성된 3개의 파일은 각각 아래와 같은 기능을 한다. %TEMP%[랜덤1].vbs : 정상 xlsx 파일을 실행 %TEMP%[랜덤2].vbs : *.scr 파일을 삭제

The content repeatedly describes threat actors and malware using cmd.exe, the Windows command shell, to execute commands, launch payloads, run batch files, and automate actions on compromised hosts.

APT-C-36 has embedded a VBScript within a malicious Word document which is executed upon the document opening.

Royal Road is a tool that generates RTF files that exploit the Microsoft Office Equation Editor vulnerabilities (CVE-2017-11882, CVE-2018-0798, CVE-2018-0802).

파일 실행 시 위와 같이 정상 엑셀파일을 함께 실행하여 사용자 PC에 악성코드가 실행되는 것을 알기 어렵게 한다.

Як результат, комп'ютер жертви буде уражено шкідливою програмою Bisonal (в одному з випадків використовується завантажувач QuickMute)

"Bisonal has used the Windows API to communicate with the Service Control Manager to execute a thread"; "Winnti for Windows can use Native API to create a new process and to start services"

"An embedded legitimate executable that is vulnerable to DLL search order hijacking... A malicious DLL loaded... via DLL search order hijacking."

During the 2015 Ukraine Electric Power Attack, Sandworm Team modified in-registry Internet settings to lower internet security before launching rundll32.exe ... AADInternals can modify registry keys ... ADVSTORESHELL is capable of setting and deleting Registry values ... [many additional examples].

During the 2016 Ukraine Electric Power Attack, Sandworm Team used an arbitrary system service to load at system boot for persistence for Industroyer. They also replaced the ImagePath registry value of a Windows service with a new backdoor binary.

The content repeatedly describes malware and threat actors establishing persistence by adding values under Registry Run keys such as HKCU\Software\Microsoft\Windows\CurrentVersion\Run and HKLM\Software\Microsoft\Windows\CurrentVersion\Run, and by placing shortcuts or files in Startup folders.

During the 2016 Ukraine Electric Power Attack, Sandworm Team used an arbitrary system service to load at system boot for persistence for Industroyer. They also replaced the ImagePath registry value of a Windows service with a new backdoor binary.

The content repeatedly describes malware and threat actors establishing persistence by adding values under Registry Run keys such as HKCU\Software\Microsoft\Windows\CurrentVersion\Run and HKLM\Software\Microsoft\Windows\CurrentVersion\Run, and by placing shortcuts or files in Startup folders.

The content repeatedly describes payloads, strings, configuration files, scripts, URLs, and binaries being obfuscated or encoded using Base64, XOR, RC4, AES, RSA, hex encoding, custom algorithms, and other methods across many malware families and threat actors.

"Sandworm Team used UPX to pack a copy of Mimikatz"; "APT38 has used several code packing methods such as Themida, Enigma, VMProtect, and Obsidium"; "Lazarus Group packed malicious .db files with Themida to evade detection."

Examples throughout the content include 'encrypted payloads decrypted and executed in memory,' 'encrypts its configuration file,' 'AES-encrypted resource,' 'RC4 encrypted embedded scripts,' and 'payload includes an encrypted main component.'

유포 파일명은 xlsx 엑셀 또는 ppt 파워포인트 문서 파일로 보이지만, 유니코드 RLO(Right to Left Override) 방식을 이용하여 파일 확장자를 다른 형태로 보이도록 하였다. 실제 악성 파일은 *.scr 파일이다.

Akira has used legitimate names and locations for files to evade defenses.

Bisonal has deleted Registry keys to clean up its prior activity ... FIN8 has deleted Registry keys during post compromise cleanup activities ... SUNBURST ... deleted previously-created Image File Execution Options (IFEO) Debugger registry values and registry keys related to HTTP proxy to clean up traces of its activity.

The content repeatedly describes malware and threat actors deleting files, directories, droppers, logs, scripts, temporary files, exfiltrated archives, and uninstalling themselves to cover tracks or reduce forensic artifacts.

The content is a long ATT&CK-style listing of malware and threat groups that 'decrypt', 'decode', 'deobfuscate', 'unpack', or 'decompress' payloads, strings, configuration data, shellcode, and files prior to execution or use.

Adversaries may abuse rundll32.exe to proxy execution of malicious code. Using rundll32.exe, vice executing directly (i.e. Shared Modules), may avoid triggering security tools that may not monitor execution of the rundll32.exe process because of allowlists or false positives from normal operations.

Bisonal02 contains an anti-sandbox trick based on the network... If it succeeds, however, it is a sign that the sample is being run in an environment that resolves even non-existent URL addresses to valid IP addresses.

"An embedded legitimate executable that is vulnerable to DLL search order hijacking... A malicious DLL loaded... via DLL search order hijacking."

QuickMute ... забезпечує ... in-memory запуск пейлоаду

During the 2015 Ukraine Electric Power Attack, Sandworm Team modified in-registry Internet settings to lower internet security before launching rundll32.exe ... AADInternals can modify registry keys ... ADVSTORESHELL is capable of setting and deleting Registry values ... [many additional examples].

The content repeatedly describes malware and threat actors querying, enumerating, opening, and reading Windows Registry keys and values, e.g., "APT41 queried registry values to determine items such as configured RDP ports and network configurations" and "Reg may be used to gather details from the Windows Registry of a local or remote system at the command-line interface."

AdFind can extract subnet information from Active Directory; actors used ipconfig /all after exploiting a machine; numerous malware and groups used ipconfig, ifconfig, arp, route, netsh, nbtstat, NBTscan, and related APIs to gather IP, MAC, DNS, DHCP, gateway, proxy, domain, ARP cache, routing, and adapter details.

Tasklist can be used to discover processes running on a system. Numerous malware families and threat groups are described as listing running processes, collecting PIDs, checking for specific process names, or enumerating loaded modules.

The content repeatedly describes malware and threat actors collecting OS version, computer name, architecture, CPU, memory, disk, BIOS, language, and other host details; examples include use of commands such as ver, systeminfo, hostname, uname -m, and WMI to gather host information.

The content is a long ATT&CK-style listing of groups and malware that can 'list files and directories,' 'search for files,' 'enumerate drives,' 'gather file metadata,' or 'browse file systems' on compromised hosts.

The content repeatedly describes malware and threat actors collecting the current date, time, or time zone from victim systems, including examples such as "The net time command can be used... to determine the local or remote system time" and commands like "net time \\hostname" and "w32tm /tz".

Bisonal02 contains an anti-sandbox trick based on the network... If it succeeds, however, it is a sign that the sample is being run in an environment that resolves even non-existent URL addresses to valid IP addresses.

MS17-010によりRCEを実行する「tools.exe」というEXEファイルを実行している。

ADに対するマルウェアのアップロードをしている。…upload file success!

The content repeatedly describes threat actors and malware collecting, stealing, identifying, copying, or staging files, documents, credentials, logs, databases, and other information from compromised hosts or local systems.

Many entries describe XOR, XOR/ADD, bitwise NOT and XOR, ROR plus XOR, hexadecimal encoding after encryption, and custom encoding/obfuscation of HTTP traffic or beacons.

C&C 주소 http[:]//imbc[.]onthewifi[.]com/ks8d[IP주소]akspbu.txt

The content is a long ATT&CK-style listing showing numerous malware families and threat groups that 'use HTTP,' 'use HTTPS,' 'HTTP POST requests,' 'HTTP GET requests,' or 'HTTP/S' for command and control communications.

"APT41 used a tool called CLASSFON to covertly proxy network communications." / "BADCALL functions as a proxy server between the victim and C2 server." / "Sandworm Team's BCS-server tool can create an internal proxy server to redirect traffic..."

Adversaries may use a non-application layer protocol for communication between host and C2 server or among infected hosts within a network. Specific examples include use of network layer protocols, such as the Internet Control Message Protocol (ICMP), transport layer protocols, such as the User Datagram Protocol (UDP), session layer protocols, such as Socket Secure (SOCKS), as well as redirected/tunneled protocols, such as Serial over LAN (SOL).

The content repeatedly describes malware and threat actors that can "download files from C2," "download additional payloads," "upload and download files," "retrieve payloads from the C2 server," and "copy files to remote machines."

ADVSTORESHELL C2 traffic is encrypted, then encoded with Base64 encoding. APT19 HTTP malware variant used Base64 to encode communications to the C2 server. APT33 has used base64 to encode command and control traffic.

The content repeatedly references RAT families and backdoors such as Gh0st RAT, htpRAT, Rehashed RAT, Bisonal, XSLCmd, Sakula, and Xsser mRAT.

Use of dynamic DNS domains with names impersonating legitimate services to stay under the radar and not raise suspicion in the network log files.

The content is a catalog of malware and threat groups that encrypt command-and-control communications using algorithms such as DES, AES, RC4, XOR, Blowfish, RSA, Camellia, RC2, RC6, and custom ciphers.

"3PARA RAT command and control commands are encrypted within the HTTP C2 channel using the DES algorithm in CBC mode..."; "APT33 has used AES for encryption of command and control traffic."; "Carbanak encrypts the message body of HTTP traffic with RC2 (in CBC mode)."; "Duqu ... data stream can be encrypted with AES-CBC."; "PoisonIvy uses the Camellia cipher to encrypt communications."

Bisonal has a uniquely long history of use and continued development by its creators, such as expanding features for file searching and exfiltration...

The following table shows the list of backdoor commands this sample supports. Command Meaning 0x000000CA terminates process