Phorpiex, an enduring botnet known for extortion campaigns and for using old-fashioned worms that spread via removable USB drives and instant messaging apps, began diversifying its infrastructure in recent years to become more resilient and to deliver more dangerous payloads. Today, the Phorphiex botnet continues to maintain a large network of bots and generates wide-ranging malicious activities.

These activities, which traditionally included extortion and spamming activities, have expanded to include cryptocurrency mining. From 2018, we also find an increase in data exfiltration activities and ransomware delivery, with the bot installer observed to be distributing Avaddon, Knot, BitRansomware( DSoftCrypt/ ReadMe ), Nemty, GandCrab, and Pony ransomware, among other malware.

The botnet’s geographic targeting for bot distribution and installation expanded, too. Previous campaigns focused on targets in Japan, but more recent activity showed a shift towards a more global distribution.

World map showing global distribution of Phorpiex botnet ativity

Figure 1. Global distribution of Phorpiex botnet activity

The Phorpiex botnet has a reputation for being simplistic and absence robustness, and it has been hijacked by security researchers in the past. Its tactics, techniques, and procedures( TTPs) have remained largely static, with common commands, filenames, and execution patterns nearly unchanged from early 2020 to 2021. To support the enlargement of the union, nonetheless, Phorpiex has shifted some of its previous command-and-control( C2) architecture away from its traditional hosting, favoring realm generation algorithm( DGA) realms over branded and static domains.

This evolution characterizes the role of botnets in the threat landscape and the motivation of attackers to persist and remain effective. The threat ecosystem relies on older botnets with large and diverse network of compromised machines to deliver warheads at low costs. And while many of the older botnet architectures have been chiefly classified as spam delivery mechanisms, these infrastructures are critical for newer, modular delivery mechanisms.

Phorpiex also demonstrates that bots, which are some of oldest types of threats, continue to affect consumer customers but notably brings increasingly more serious threats to enterprise networks. Despite being traditionally associated with lower-risk activity like extortion and spamming, Phorpiex operators’ decision to move to more impactful malware and actions is altogether at the whim of the attackers.

Understanding botnets and associated infrastructure, botnet malware, their activities and warheads, and how they evolve provides insight into attacker motive and guaranteed by durable protection against some of the most prevalent threats today. At Microsoft, we continue to conduct in-depth research into these threats. These expert investigations add to the massive threat intelligence that inform Microsoft 365 Defender services and the protections they provide. Microsoft 365 Defender delivers coordinated cross-domain defense against the various malware, emails, network connections, and malicious activity associated with Phorpiex and other botnets.

Distribution, expansion, and functioning

Phorpiex’s sprawling botnet operation can be divided into three main segments 😛 TAGEND

Distribution of the bot loader: The bot loader has been propagated through various categories of intends over the years, including being loaded by other malware, freeware, and unwanted programs, or delivered by phishing emails from already-infected bots. Phorpiex has also spread via productivity platforms, as well as via instant messaging and USB drives. Mailing botnet: In addition to spreading the bot loader via email, the botnet is used to generate currency. It done likewise via extortion and spam campaigns as well as through a variety of other types of financially motivated malware. Malware delivery botnet: In recent years, the botnet has been observed installing ransomware, cryptocurrency miner, and other malware kinds, indicating the expansion of the botnet’s activities by the Phorpiex operators or as part of malware-as-a-service scheme.

From December 2020 to February 2021, the Phorpiex bot loader was encountered in 160 countries, with Mexico, Kazakhstan, and Uzbekistan registering the most encounters.

Column chart showing top 10 countries with most Phorpiex encounters

Figure 2. Countries with the most encounters of the Phorpiex bot loader

In December 2020 and January 2021, we find non-weaponized staging of Knot ransomware on Phorpiex servers. In February, we likewise saw merchandise malware such as Mondfoxia( also known as DiamondFox) in these servers. These recent developments indicate new loader and monetization strategies under active development.

The combination of the wide variety of infection vectors and outcomes stimulates the Phorpiex botnet appear chaotic at first glance. However, for many years Phorpiex has maintained a consistent internal infrastructure utilizing similar domains, command-and-control( C2) mechanisms, and source code.

The wide range of infection vectors used by Phorpiex requires a unified security approach that ensures protection is delivered on the endpoint, network, email, and applications. Microsoft 365 Defender’s advanced menace protection engineerings see malicious activity in each of these domains. Furthermore, the correlation of these cross-domain threat data surfaces additional malicious activity, permitting Microsoft 365 Defender to provide coordinated and comprehensive protection against Phorpiex.

Bot distribution and installing

Phorpiex maintains and expands its network of bot-infected computers by distributing the Phorpiex bot loader. In 2020 and 2021 we find the bot loader being spread through Phorpiex bot-delivered emails with. zip or other archive file attachments, downloaded from sham download sites for software( such as photo editing software, screensaver, or media musicians ), or downloaded by other malware also delivered through email. These multiple entry points demonstrate the modular nature of the malware economy.

Regardless of distribution mechanism, however, the bot loader operates in a fairly uniform fashion. It applies three distinct types of C2 to fulfil different purposes during and after installing 😛 TAGEND

Downloading the Phorpiex malware implant Downloading updates to the Phorpiex implant and new exploit modules Checking in with C2 infrastructure to deliver cryptocurrency or return data

The malware implant is initially downloaded from websites such as trik [.] ws( historically) or, more recently, a malware hosting storehouse, worm [.] ws. We are likewise noticing a shift to using more dedicated IP-based C2 and delivery websites, such as 185 [.] 215 [.] 113 [.] 10 and 185 [.] 215 [.] 113 [.] 8. A notable Phorpiex behavior is the downloading of numbered modules, typically numbered 1-10, with URL tracks such as < realm >. com/ 1, . com/ 2, . com/ 3, continuing this pattern for as many additional components as needed. As these downloads do not happen through standard web traffic, network-level protection is necessary to prevent malicious downloads. In a very recent development, we observed that most Phorpiex bot loader malware have abandoned branded C2 realms and have completely moved to using IPs or DGA domains. Nonetheless, as in the past, the operators neglected to register all the potential websites that the DGA domains resolve to.

When downloaded and operated, the implant attempts to connect to legitimate external websites like WIPMANIA.com to get IP information. It does this repeatedly during subsequent check-ins, and then begins connecting to hardcoded C2 servers. During these check-ins, the implant checks the device’s regional decideds and exits if it’s operating in a non-desired region, such as Ukraine. Favored regions include countries in East Asia as well as English-speaking countries.

The loader modules and updates are pulled from a variety of attacker-owned domains. These domain-names typically begin with a second-level domain( 2LD) of TLDR, TSRV, or THAUS and concluded with an potpourrus of unorthodox TLD such as. WS,. TOP,. RU,. CO,. TO,. SU .,. CC, and. IO. As has been pointed out by other researchers, the TSRV and TLDR are likely references to “Trik Server” or “Trik Loader”, as many of the internals of the malware utilize Trik as proprietary name.

Regular connections to these attacker-owned domains continue during infection, such that machines that become infected for months receive new loader versions and capabilities. Modules downloaded from C2 can include additional malware, ransomware, cryptocurrency mining functionality, worming functionality, and the Phorpiex mailing botnet functionality. It is most common for a bot to be participating in mailing and crypto mining, as these appear to have been driving revenue generation for the operators during non-ransomware initiatives.

The bot likewise establishes perseverance and attempts to disable security controls. This includes modifying registry keys to disable firewall and antivirus popups or functionality, overriding proxy and browser specifies, specifying the loader and executables to run at startup, and adding these executables to the authorized application lists. A sample of the keys varied is below, with minor modifications from version to version of the loader 😛 TAGEND

\ FirewallPolicy \ StandardProfile \ AuthorizedApplications \ List \Microsoft\Windows\CurrentVersion\Run\Host Process for Windows Services \Microsoft\Security Center \ AntiVirusOverride \Microsoft\Security Center \ AntiVirusDisableNotify \Microsoft\Security Center \ FirewallOverride \Microsoft\Security Center \ FirewallDisableNotify \Microsoft\Windows\CurrentVersion\Internet Settings \ Connections \ SavedLegacySettings \Microsoft\Security Center \ UpdatesOverride \Microsoft\Security Center \ UpdatesDisableNotify \Microsoft\Windows NT \ CurrentVersion \ SystemRestore \Microsoft\Windows Defender \ Real-Time Protection \ DisableBehaviorMonitoring \Microsoft\Windows Defender \ Real-Time Protection \ DisableOnAccessProtection \Microsoft\Windows Defender \ Real-Time Protection \ DisableScanOnRealtimeEnable

Enabling tamper protection in Microsoft Defender for Endpoint prevents the bot from inducing modifications related to Microsoft Defender services. Microsoft Defender for Endpoint automatically cleans up modifies made by the bot( if any) during menace cleanup and remediation. Security procedures squads can use advanced hunting capabilities to locate these and similar adjustments. Administrators are also welcome to disable “Local Policy Merge” to prevent local firewall policies from get in effect over group policies.

As the bot loader updates, the key values change to reflect new files, randomized file paths, and masqueraded system files. The instance below shows a alter from SVCHOST to LSASS 😛 TAGEND

KEY NAME: HKEY_CURRENT_USER \[ ID ]\ Software \ Microsoft \ Windows \ CurrentVersion \ Run OLD VALUE: C :\ 14466211462 96 \ svchost.exe New VALUE: C :\ 19197205241 657 \ lsass.exe

At varying intervals, the bot implant accumulates lists of files and exfiltrates that data to external IP addresses leased by the attacker, many of which likewise serve as C2. When additional malware is installed, the pulling is initiated from the implant itself. The malware is staged on the Phorpiex operators’ servers prior to new campaigns or on the shared websites such as worm [.] ws.

The bot checks in routinely, often weekly and sometimes even daily. It does this to upload any outcomes from the various modules that the bot installs, such as coin mining deposits or spam activity.

In addition to detecting and blocking the bot malware through its endpoint protection platform( EPP) and endpoint detection and response( EDR) abilities, Microsoft Defender for Endpoint’s network protection defends against botnet activities like connecting to attacker-controlled servers, mimicking system files, and downloading implants and additional payloads.

Self-spreading via remote drives

One of the more unique and easily identifiable Phorpiex behavior when it spread chiefly via USB involves a check that occurs routinely for all connected remote drives. The bot then generates a series of concealed folders on those drives with underscores( e.g ., “__”) and then changes the registry attributes to construct these appear invisible to the user. The bot then copies all its file configurations and include a malicious DriveMgr.exeI, a copy of the loader, as well as a. lnk file that runs the malware when opened. This activity has been largely consistent since 2019. This functionality offerings a self-spreading mechanism that offers a backup style to expand the bot implant base. Commands consistent with this Phorpiex worming activity are 😛 TAGEND

ShEllExECutE= __ \\ DriveMgr.exe “cmd.exe”/ c start __& __ \ DriveMgr.exe& exit

Microsoft Defender for Endpoint offers multiple layers of protection against USB menaces. This includes real-time scanning of removable drives and onslaught surface reduction regulation to block untrusted and unsigned processes that run from USB. Microsoft Defender for Endpoint also enables organizations to monitor and control removable drives, for example let or block USB based on granular configurations, and monitor USB activities.

Phorpiex as a send botnet

For several years, Phorpiex used infected machines to deliver extortion, malware, phishing, and other content through large-scale email campaigns. These emails span a large set of lures, subject lines, speeches, and recipients, but there are key defines of characteristics that can identify emails sent from the Phorpiex botnet 😛 TAGEND

Spoofed sender domain, sender username, and sender display epithet Sender domain of 4 random digits Sender username use a generic name with a variety of numbers Subjects or entices referencing singular names, heights and weights, surveillance Body of the message often referencing dating services or extortion substance for ransom Presence of Bitcoin, DASH, Etherium, or other cryptocurrency billfolds ZIP files or other file forms purporting to be images such as JPG files or photo types

These patterns include language more commonly used in consumer extortion emails, which reference having illicit photos or videos of the recipient. These are also the same enticements that are used to distribute the bot installer as well as ransomware or other malware. The messages often include age-old passwords of individuals gathered from publicly available listings, a technique that attackers use to add credibility whether the mail is received in a corporate environment or at home.

Microsoft Defender for Office 365 sees malicious emails sent by the Phorpiex botnet. These include the extortion and phishing emails, as well as messages carrying malware, whether the Phorpiex loader itself or other malware. Microsoft Defender for Office 365 customers AI and machine learning to detect customer and realm impersonation, informed by its comprehensive visibility into email menaces as well as through in-depth research like this.

Spam and extortion campaigns

Phorpiex is well known for illicit image or video-based extortion phish and spam campaigns, also known as “sextortion”. These campaigns target a large variety of regions and speeches, which is a different defined of targets from bot distribution activities. These generally do not deliver malware directly. They are meant to collect revenue for the operator by asserting that they have already compromised a machine and have access to damaging substance regarding the recipient.

Sextortion campaigns have been quite popular in recent years and generally involve payment from the main victims in cryptocurrency. We find Phorpiex operators involving payment primarily through Bitcoin and Dash. Examples of one such cryptocurrency profit volume from a campaign in late February 2021 targeting English speaking consumers is below, with the subject “Payment from your account”.

There are several public monitors of extortion wallets operated by Phorpiex, which have ascertained the operators of the botnet running numerous wallets during any dedicated week. We find the below example in which an operator requested $950 from customers and amassed over $13,000 in 10 days.

Line graph showing daily amount of cryptocurrency in a particular cryptocurrency address

Figure 3. Cryptocurrency profit volume from a single billfold used in spam extortion campaign in late February 2021. Data from BitInfoCharts.

In late 2020 and early 2021 we likewise observed this extortion strategy exploiting dreads about security vulnerabilities in teleconferencing applications such as Zoom. The messages claimed that a vulnerability is what allowed the operators to capture their extortion material.

Screenshot of sample email used in campaign

Figure 4. Example of an extortion email seduce from late 2020

Screenshot of sample email used in campaign

Figure 5. Example of a Korean language extortion email lure from early 2021

In addition to the instances above, Phorpiex is often distributed via business email compromise and contain no links or URLs. This hampers many automatic detecting abilities an organization might have in place.

Phishing, malware, and ransomware campaigns

Phorpiex-powered phishing campaigns as well as bot implant installations deliver secondary malware as well as standard extortion and spam. The tactics involving the spread of emails are the same, with the only changes being in the attachments or connections. Malware involving malicious Office documents is interspersed with deliveries of the bot implant or direct ransomware deliveries, which are often contained within. ZIP attachments.

Since 2019, many of the malware-carrying emails from Phorpiex use the same seduces, subject lines, and attachment file names. The emails use a haphazardly made feminine name in the subject or reference an embarrassing or improperly procured photo, and either contain extortion or deliver ransomware. As part of the social engineering seduce, he malware attachments masquerade as. jpg files or other file characters, while showing as. zip or. js files.

Screenshot of sample email campaign

Figure 6. Example of an email lure including malicious ZIP attachment masquerading as an image of an actress

In Summer and Fall 2020 many new Phorpiex infections began to spread use archive files to deliver BitRansomware and Avaddon. Avaddon simply began spreading in mid to late 2020 and its distribution seems to have been tightly read in conjunction with Phorpiex because it inception.

In the month of August 2020, there was also an increase in the number of bot implants installed on machines, corresponding with the ransomware increase. At this time, most instances of ransomware perpetrated by Phorpiex were carried through the bot implant itself.

Phorpiex as malware delivery botnet

In addition to operating as a mailing botnet, Phorpiex has evolved to deliver other malware as well, most notably cryptocurrency mining malware and ransomware.

Cryptocurrency mining malware

In 2019 Phorpiex started utilizing an XMRIG miner to monetize the hosts with Monero. This module is included in almost all bot installings at the time of infection and communicates mainly over port 5555. This behavior might be coupled with other malware, but in this instance, it is associated with the masqueraded system process used by the rest of the Phorpiex implant( i.e ., SVCHOST.exe or LSASS.exe ).

The miner is downloaded as a module masquerading as WINSYSDRV.exe It stores its configuration locally and checks it sporadically. The miner does this from additional masqueraded system process injected into legitimate processes to read its configuration and to mine.

The WINSYSDRV.exe file routinely kicks off a series of heavily nested process preceded by a PING with a long wait, which is intended to avoid sandboxes. This command are listed below 😛 TAGEND

cmd.exe/ C ping[ INTERNAL IP] -n 8 -w 3000> Nul& Del/ f/ q “C:\ProgramData\PnQssBdbSh\winsysdrv.exe”& “C:\Users\[USER]\AppData\Local\Temp\winsysdrv.exe”

In prior versions, this command utilized the legitimate but hijacked WUAPP.exe process. Recently “were having” seen NOTEPAD.exe used to read the track, which is a variant of C :\ ProgramData \[ RandomString] cfg 😛 TAGEND

“C:\Windows\System32\wuapp.exe” -c “C:\ProgramData\ADwXcSSGvY\cfgi”( 2019 -2 020) “C:\Windows\System32\wuapp.exe” -c ” C :\ ProgramData \ PnQssBdbSh \ cfgi”( 2020) “notepad.exe” -c ” C :\ ProgramData \ PnQssBdbSh \ cfgi”( 2020 -2 021) “notepad.exe” -c ” C :\ ProgramData \ PnQssBdbSh \ cfg”( 2020 -2 021)

In addition to mining Monero, versions of the bot loader also upload to Bitcoin billfolds. We were able to scrape those address via downstream executables dropped by the Phorpiex loader masquerading as SVCHOST.exe or LSASS.exe. Below is an example of the balance in one such wallet address that was active from September to November 2020, embedded in a specific sample.

Line graph showing daily amount of cryptocurrency in a particular cryptocurrency address

Figure 7. Cryptocurrency profit from a single wallet used in a miner plummeted on an infected machine from September to November 2020. Data from BitInfoCharts.

In February of 2021, infected implants also downloaded additional Etherium miners. These miners create scheduled chores are labeled “WindowsUpdate” but operated the miner every minute. The miners search for graphics cards as well as other resources to use for mining with an ethermine.org mining pool. Here’s an example task creation 😛 TAGEND

schtasks/ generate/ sc minute/ mo 1/ tn WindowsUpdate/ tr% TEMP %\ System.exe

Microsoft has also observed Phorpiex variants with cryptocurrency-clipping functionality accompanying the process of establishing the loader. In these instances, the malware checks clipboard values for a valid cryptocurrency billfold ID. If it acquires one, it determines its own hardcoded value. This method lets attackers to profit from existing mining installations or prior malware without having to bring in new software or remove old instances.

Microsoft Defender for Endpoint detects and blocks cryptocurrency mining malware and coin mining activity in general. To continue enhancing this detection capability, Microsoft recently integrated Intel Threat Detection Technology( TDT) into Microsoft Defender for Endpoint, allowing our endpoint detection and response capabilities to use silicon-based threat detection to better protect against coin mining malware.

Ransomware

Phorpiex has been associated with multiple ransomware families through the years. Phorpiex either delivers ransomware on behalf of other groups using those operators’ infrastructure or host the ransomware themselves. The latter is more common in the case of commodity kits like Avaddon and Knot that the Phorpiex operators may develop themselves.

As recently as February 2021, Avaddon was under active growth. Like the Phorpiex loader itself, Avaddon performs speech and regional checks for Russia or Ukraine before running to ensure simply favored regions are targeted.

The initial Avaddon executable is located in the TEMP folder, and it generally employs a series of random characters as file expansion for encrypted files. Before deleting backups and encrypting the drive, it corroborates that UAC is disabled by checking if certain registry keys are set to “0”, modifying the value if not 😛 TAGEND

\ REGISTRY \ MACHINE \ SOFTWARE \ Microsoft \ Windows \ CurrentVersion \ Policies \ System \ EnableLUA= “0” \REGISTRY\MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\ConsentPromptBehaviorAdmin= “0” \REGISTRY\MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\EnableLinkedConnections= “1”

After achieving the privilege level needed, encryption usually occurs on the individual machine without lateral movement, though that is subject to change based on the operator’s monetization strategy. The procedure for deleting backups, like most ransomware, is performed with this command 😛 TAGEND

cmd/ c wmic.exe SHADOWCOPY/ nointeractive cmd/ c wbadmin DELETE SYSTEMSTATEBACKUP cmd/ c wbadmin DELETE SYSTEMSTATEBACKUP -deleteOldest cmd/ c bcdedit.exe/ placed default recoveryenabled No cmd/ c bcdedit.exe/ placed default bootstatuspolicy ignoreallfailures cmd/ c vssadmin.exe Delete Shadows/ All/ Quiet

Microsoft Defender for Endpoint detects and blocks the ransomware. It also sees and elevates the following alertings for the encryption and backup deletion behaviors, enabling security functionings squads to be notified and immediately respond to ransomware activity on their environment 😛 TAGEND

Ransomware behavior detected in the file system File backups were deleted

We have observed that the external commands and behaviors of the Avaddon ransomware have largely remained the same since its introduction in June-July 2020. This includes the tendency to masquerade as the system file Taskhost.exe. Avaddon, which demands a ransom in Bitcoin equivalent to $ 700, is still active today and being actively distributed by Phorpiex using new bot loaders that are not substantially different in behavior. Microsoft Defender for Endpoint continues to provide durable protection against these new campaigns.

Other ransomware is slightly less common lately, but in December 2020, a non-weaponized version of Knot ransomware was staged on Phorpiex-operated servers. It did not seem to have had any infections yet as this may have been a test version. This ransomware shares a high degree of similarity to the Phorpiex loader itself and enhanced versions had still not been been recognized. Like Avaddon, Knot typically demands relatively smaller sums of fund in Bitcoin, equal to $ 350. The ransom notes generally necessitate Bitcoin payment to a billfold, though no pays seems to have been made that month.

Line graph showing daily amount of cryptocurrency in a particular cryptocurrency address

Figure 8. Cryptocurrency profit volume from a single billfold attached to a Knot ransomware sample in early 2021, depict no payments of the asking price. Data from BitInfoCharts.

Defending against botnets and associated activity

Botnets drive a huge portion of the malware economy, and as the resilience of Phorpiex presents, they evolve to adapt to the ever-changing threat environment. Our many years of experience analyzing, monitoring, and even working with law enforcement and other partners to take down botnets tell us that alternative infrastructures rise as attackers try to fill in the void left by interrupted botnets. Typically, new infrastructures are born as a result of these movements, but in the case of Phorpiex, an established botnet accommodates and takes over.

The wide range of malicious activities associated with botnets, as we detailed in this in-depth research into Phorpiex, represent the spectrum of threats that organizations face today: various assault vectors, multiple spreading mechanisms, and a diverse set of warheads that attackers can change at will. To combat these threats, organizations need security answers that deliver cross-domain visibility and coordinated defense.

Microsoft 365 Defender leverages the capabilities and signals from the Microsoft 365 security portfolio to correlate threat data from endpoints, email and data, identities, and cloud apps to provide comprehensive protection against threats. Microsoft Defender for Endpoint sees and blocks malware, other malicious artifacts, and malicious behaviour associated with botnet activity, as well as the deployment of secondary warheads like cryptocurrency miners and ransomware. Features like attack surface reduction, tamper protection, and safety controls for removable media further help prevent these attacks and harden networks against menaces in general. Microsoft Defender for Office 365 detects the malicious attachments and URLs in emails generated by the mailing the activities of the Phorpiex botnet.

Our industry-leading visibility informs AI and machine learning technologies that power the automatic prevention, detecting, and remediation of threats, as well as the rich determine of investigation tools available to defenders for hunting, analyzing, and resolving attacks. The recently generally available unified Microsoft 365 Defender security center integrates capabilities so champions can manage all endpoint, email, and cross-product investigations, configuration, and remediation with a single portal.

Our understanding of how botnets operate and evolve, through in-depth research like this, further enriches our ability to continue delivering defenses against the threats of today and the future. Learn how Microsoft 365 Defender stops onslaughts with automated, cross-domain questions of safety and built-in AI.

Microsoft 365 Defender Threat Intelligence Team

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