sentence stringlengths 1 13.5k | labels listlengths 0 15 | doc_title stringclasses 84
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|---|---|---|
xxZmgLbpuJ = 0 for position in list(range(256)): xxZmgLbpuJ | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
= (xxZmgLbpuJ + position_array[position] + ord(key_array[position])) | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
% 256 YAFIh = position_array[position] position_array[position] = position_array[xxZmgLbpuJ] position_array[xxZmgLbpuJ] = YAFIh DmqRsaOvxUH | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
xxZmgLbpuJ | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
= 0 new_array = | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
[] for position in list(range(len(dec_list))): DmqRsaOvxUH | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
+= 1 DmqRsaOvxUH | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
%= 256 xxZmgLbpuJ | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
+= position_array[DmqRsaOvxUH] | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
xxZmgLbpuJ %= 256 YAFIh = position_array[DmqRsaOvxUH] position_array[DmqRsaOvxUH] = position_array[xxZmgLbpuJ] position_array[xxZmgLbpuJ] = YAFIh new_array.append(dec_list[position] ^ | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
position_array[((position_array[DmqRsaOvxUH] | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
+ position_array[xxZmgLbpuJ]) | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
% 256)]) return new_array Figure 5 - Python Script to Decode | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
The output decimal list from this function was then converted from bytes, resulting in an executable for the first block and shellcode for the second block. | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Shellcode The malware and shellcode were allocated memory in the process space using VirtualAlloc. | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
After being copied into memory, the shellcode was executed using the callback function pointer in CallWindowProc, shown in Figure 6 below. | [
"T1106"
] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Other samples leverage the function Delegate. | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
DynamicInvoke instead. | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Figure 6 - Shellcode and Payload Being Loaded Into Memory Figure 7 - Encoded shellcode in Project File The shellcode (encoded shown in Figure 7 above) calls, shown in Figure 8 below, were mainly: LoadLibraryW, VirtualAlloc, CreateProccessW, and ZwUnmapViewOfSection. | [
"T1027",
"T1106"
] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
LoadLibraryW loads the module, VirtualAlloc allocates the memory, CreateProcessW created a process, and ZwUnmapViewOfSection is used to unmap memory from a virtual space. | [
"T1106"
] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
These were used to inject the payload into process memory. | [
"T1055"
] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Figure 8 - Calls made by the shellcode Payloads RemcosRAT Analyzed File – MD5 – 04fc0ca4062dd014d64dcb2fe8dbc966 The payload from the project files was a remote access tool (RAT) called Remcos. | [
"T1219"
] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Remcos is a commercial software created by Breaking Security that, according to their user manual, can be used for remote control, remote admin, remote anti-theft, remote support and pentesting.[5] | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
However, Remcos has often been used by threat actors for malicious purposes. | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
The software, written in C++, enables full access to the infected machine with features including, but not limited to: Anti-AV Credential harvesting Gathering system information Keylogging Persistence Screen capture Script execution The themes used by actors to distribute Remcos have varied, including changes designed ... | [
"T1056.001",
"T1082",
"T1113"
] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
For example, recent Remcos campaigns were observed utilizing Tax Day lures.[6] | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
The version used in this campaign was 2.6.0, which was released in July 2020 (Figure 9). | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Additional functions Remcos has been known to utilize are shown in Table 1 below. | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
The persistence technique is simply adding a run registry key for persistence (Figure 11). | [
"T1547.001"
] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Remcos has also been observed using its “Watchdog” feature to restart the RAT if it is terminated (Figure 12). | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Figure 9 - Remcos Version 2.6.0 Being Used Figure 10 - connecting to C2 Figure 11 - Adds Run Registry Key for Persistence Figure 12 - Watchdog Module Figure 12 shows the “Watchdog” module which restarts Remcos in the event the program is terminated. | [
"T1547.001"
] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Table 1 - Remcos 2.6.0 Features Remote Scripting Notifications | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Webcam Capture Remote Command Line Clear Logins Remote Chat File Manager Remote Input Microphone Capture SOCKS Proxy Keylogger Login Cleaner Screen Logger Local Utilities Browser History Registry Editor Password Recovery Visibility mode RedLine Stealer Analyzed File – rehoboams.exe MD5 – 6d3e8a2802848d259a3baaaa78701b9... | [
"T1056.001",
"T1059.003",
"T1112",
"T1113"
] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
In a similar MSBuild project file to the Remcos dropping .proj file, we found another project file named “vwnfmo.lnk“ where RedLine Stealer was dropped instead of Remcos, shown in Figure 13 below. | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
RedLine Stealer is written in .NET and has been observed stealing multiple types of data (full list shown in Table 2 below), including: : Cookies Credentials (chat clients, VPNs, crypto wallets, browser ) | [
"T1005"
] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Crypto wallet NordVPN (existence of and credentials) Stored web browser information (credit card, username, and password) | [
"T1082"
] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
System Information RedLine will search for the existence of multiple products that include cryptocurrency software, messaging apps, VPNs, and web browsers (full list shown in Table 2 below). | [
"T1082"
] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Figure 13 - RedLine .NET | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Information Stealer Figure 14 - RedLine Functions Figure 15 - Checks for NordVPN Installation Figure 15 above shows RedLine checking for NordVPN on the machine. | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
If the path exists, the next function of this malware is to check for the user config to steal the credentials. | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
This function also enables RedLine to steal credentials for additional installed applications. | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Table 2 - Installs RedLine Scans for Chrome GameLauncher for Steam Filezilla Guarda Gecko Jaxx Armory Metamask Atomic Monero Coinom OpenVPN DesktopMessenger for Telegram NordVPN Discord ProtonVPN Electrum Tronlink Ethereum Yoroi Conclusion The threat actors behind this campaign used fileless delivery as a way to bypass... | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
This campaign highlights that reliance on antivirus software alone is insufficient for cyber defense, and the use of legitimate code to hide malware from antivirus technology is effective and growing exponentially. | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Focusing on cybersecurity training and hygiene, as well as a defense-in-depth strategy, are some recommended courses of action for countering this threat. | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Endnotes [1] “MSBuild,” Microsoft Visual Studio Docs, accessed May 3, 2021, published November 4, 2016, https://docs.microsoft.com/en-us/visualstudio/msbuild/msbuild?view=vs-2019. | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
[2] Ibid. | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
[3] “What Is Fileless Malware?,” McAfee, accessed May 3, 2021, https://www.mcafee.com/enterprise/en-gb/security-awareness/ransomware/what-is-fileless-malware.html. | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
[4] “Internet Security Report – Q4 2020,” WatchGuard, accessed May 4, 2021, published March 30, 2021, https://www.watchguard.com/uk/wgrd-resource-center/security-report-q4-2020, 3. | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
[5] “Remcos Instructions Manual,” Breaking Security, accessed May 4, 2021, published July 2018, https://breaking-security.net/wp-content/uploads/dlm_uploads/2018/07/Remcos-Instructions-Manual-rev19.pdf, 15-16. | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
[6] Daniel Frank, “Cybereason Exposes Campaign Targeting US Taxpayers with NetWire and Remcos Malware,” Cybereason, accessed May 4, 2021, published March 18, 2021, https://www.cybereason.com/blog/cybereason-exposes-malware-targeting-us-taxpayers. | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Appendix A IOCs Project File Payload C2 Details 45c94900f312b2002c9c445bd8a59ae6 Remcos 04fc0ca4062dd014d64dcb2fe8dbc966 135.181.170.169:50845 d8a57534382a07cc0487b96350bca761 Remcos eb8b1d64429e00f2b3b49f886ee3b0b4 http://dl4.joxi.net/drive/2021/04/15/0048/3592/3153416/16/b8c104ce64.png d52d6bad3d11e9a72998608ccca572f... | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Registry Run Keys / Startup Folder Privilege Escalation T1548.002 Abuse Elevation Control: | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
Bypass User Account Control T1055 Process Injection T1055.012 Process Hollowing Defense Evasion T1140 Deobfuscate/Decode Files or Information T1112 Modify Registry T1027 Obfuscated Files or Information T1055 Process Injection T1055.002 Portable Executable Injection T1055.012 Process Hollowing T1127 Trusted Developer Ut... | [] | Threat Actors Use MSBuild to Deliver RATs Filelessly |
After FortiGuard Labs reported on RapperBot in our previous article titled So RapperBot, What Ya Bruting For? in August 2022, there was a significant drop in the number of samples collected in the wild. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
But in early October 2022, new samples with the same distinctive C2 protocol used by RapperBot were detected. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
Unlike the murky objectives of the previous campaign, it is quickly evident that these samples are part of a separate campaign to launch Distributed Denial of Service (DDoS) attacks against game servers, which we believe to be a re-emergence of a similar campaign from earlier this year. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
Affected Platforms: LinuxImpacted Users: Any organizationImpact: | [] | New RapperBot Campaign We Know What You Bruting for this Time |
Remote attackers gain control of the vulnerable systemsSeverity Level: Critical This article discusses the differences observed in this campaign and its relation to the previous RapperBot and similar campaigns in the past. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
RapperBot Rebooted FortiGuard Labs encountered this campaign by hunting for samples using the unique bot ID used by RapperBot to communicate with its Command-and-Control (C2) server, as reported in the previous article. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
But once we analyzed these new samples, we observed a significant difference between them and the earlier campaign. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
In fact, it turns out that this campaign is less like RapperBot than an older campaign that appeared in February and then mysteriously disappeared in the middle of April. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
Other related campaigns uncovered during this investigation are detailed later in this article. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
Network Protocol and Denial-of-Service (DoS) | [] | New RapperBot Campaign We Know What You Bruting for this Time |
Attacks The C2 network protocol used in previous campaigns remains essentially unchanged, with additional commands added to support the Telnet brute force. | [
"T1110"
] | New RapperBot Campaign We Know What You Bruting for this Time |
The list of commands and IDs are shown below: 0x00: Register (used by the client) | [] | New RapperBot Campaign We Know What You Bruting for this Time |
0x01: Keep-Alive/Do nothing 0x02: Stop all DoS attacks and terminate the client 0x03: Perform a DoS attack 0x04: Stop all DoS attacks 0x06: Restart Telnet brute forcing 0x07: Stop Telnet brute forcing The previously reported RapperBot campaign was limited to a few generic DoS methods against TCP and UDP services. | [
"T1110"
] | New RapperBot Campaign We Know What You Bruting for this Time |
This campaign adds DoS attacks against the GRE protocol (likely reusing the Mirai source code) and the UDP protocol used by the Grand Theft Auto: San Andreas Multi Player (SA:MP) mod. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
Here are the DoS attack commands supported by this botnet: 0x00: Generic UDP flood 0x01: TCP SYN flood 0x02: TCP ACK flood 0x03: TCP STOMP flood 0x04: UDP SA:MP flood targeting game servers running GTA San Andreas: | [] | New RapperBot Campaign We Know What You Bruting for this Time |
Multi Player (SA:MP) 0x05: GRE Ethernet flood 0x06: GRE IP flood 0x07: Generic TCP flood These specific commands, coupled with the absence of HTTP-related DDoS attacks, suggests that this campaign is primarily geared toward game server DDoS. Telnet Self-propagation The most significant difference in the new campaign wa... | [
"T1110"
] | New RapperBot Campaign We Know What You Bruting for this Time |
FortiGuard Labs has observed similar drastic modifications within RapperBot samples, as detailed in our previous report, adding and removing even DoS attack code on an apparent whim. | [
"T1110"
] | New RapperBot Campaign We Know What You Bruting for this Time |
The Telnet brute forcing code is designed primarily for self-propagation and resembles the old Mirai Satori botnet. | [
"T1110"
] | New RapperBot Campaign We Know What You Bruting for this Time |
Unlike the earlier SSH brute-forcing campaign, the plaintext credentials are embedded into the malware instead of being downloaded from the C2. | [
"T1078",
"T1110"
] | New RapperBot Campaign We Know What You Bruting for this Time |
These credentials used appear to be default credentials for IoT devices. | [
"T1078"
] | New RapperBot Campaign We Know What You Bruting for this Time |
To optimize brute forcing efforts, the malware compares the server prompt upon connection to a hardcoded list of strings to identify the possible device and then only tries the known credentials for that device. | [
"T1110"
] | New RapperBot Campaign We Know What You Bruting for this Time |
Unlike less sophisticated IoT malware, this allows the malware to avoid trying to test a full list of credentials. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
While not exactly a novel technique, it is still uncommon compared to other IoT botnets. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
Based on the prompt messages hardcoded into the malware, most of the targeted devices are IoT devices such as routers and DVRs. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
This campaign seems especially interested in older devices with the Qualcomm MDM9625 chipset, such as LTE modems. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
It attempts to specifically gain root access to these devices via a default password, despite having the same credentials in the list embedded in the binary. | [
"T1078",
"T1110"
] | New RapperBot Campaign We Know What You Bruting for this Time |
Like the earlier SSH brute-forcing campaign, once it has successfully gained access, it sends the credentials used, the compromised device’s IP address, and its architecture to the C2 server on a separate port, 5123. | [
"T1110"
] | New RapperBot Campaign We Know What You Bruting for this Time |
After reporting, the malware attempts to install its main payload binary on the compromised device. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
It first parses the Executable and Linkable Format (ELF) header of the /bin/busybox file for the e_machine field, which provides the architecture of the compromised device. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
This allows it to download and deploy a RapperBot payload of the correct architecture to ensure proper execution. | [
"T1105"
] | New RapperBot Campaign We Know What You Bruting for this Time |
This selective behavior is more efficient than the shotgun approach in most IoT malware families, whereby all the binaries for the supported architectures are downloaded and executed in the victim's system. | [
"T1105"
] | New RapperBot Campaign We Know What You Bruting for this Time |
Based on the payload binaries we collected, this botnet currently seems to only target devices running on ARM, MIPS, PowerPC, SH4, and SPARC architectures. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
Moreover, it specifically checks and stops its self-propagation if the device is detected to be running on Intel processors. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
The bot then downloads its payload via software installed on the compromised device, such as ftpget, wget, curl, or tftp, before executing the payload. | [
"T1570"
] | New RapperBot Campaign We Know What You Bruting for this Time |
If none of the software mentioned above is installed, it will extract and send an embedded binary downloader to the compromised device that executes and downloads the primary payload. | [
"T1105"
] | New RapperBot Campaign We Know What You Bruting for this Time |
Unlike in Satori, these embedded downloaders are stored as escaped byte strings, probably to simplify parsing and processing within the code. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
The binary downloaders are written by echoing the bytes and piping the content to a file in the victim system. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
As labeled in Figure 4, each binary has a hardcoded URL for downloading the payload binary of the proper architecture. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
No attempts to persist on infected or brute-forced devices were observed for this campaign. | [
"T1110"
] | New RapperBot Campaign We Know What You Bruting for this Time |
Related Campaigns FortiGuard Labs compared samples for this and related campaigns from the past to find any links with the previously reported RapperBot campaign. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
We observed that the earliest samples for this campaign were from December 2021 and that the SA:MP attack was only added in February 2022. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
This campaign mysteriously disappeared in mid-April 2022, resurfacing in Oct 2022 with the addition of the self-propagation feature. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
We also found older samples from another campaign that was active in August-September 2021 with an almost identical list of credentials. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
These samples contain slightly fewer credentials and a simpler self-propagation code that only supports downloading the payload via wget or the binary downloader embedded directly into the sample. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
This campaign did not support stopping or restarting the Telnet propagation, and while the samples support the same commands, their associated IDs did not match. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
The similar lists of credentials suggest that the threat actor behind this current campaign has access to the source code for the earlier campaign, as this code was not found in other IoT malware samples. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
Connections to RapperBot The fact that samples from both campaigns use the same C2 protocol, coupled with the absence of this campaign during the RapperBot campaign active between June and Aug 2022 and its recent reappearance, seems to be more than a coincidence. | [] | New RapperBot Campaign We Know What You Bruting for this Time |
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