Malicious PDF — malware analysis report

Static analysis result for SHA-256 5b427776da05fb7b…

MALICIOUS

PDF

251.3 KB Created: 2021-07-03 16:11:35 +07:00 Authoring application: wkhtmltopdf 0.12.6 (via Qt 4.8.7) First seen: 2021-11-21
MD5: ab2b7862e60c8b3bd9c5d66514f4c978 SHA-1: c8db7e122b419a165c9108da9f0d6be72819f562 SHA-256: 5b427776da05fb7b626d031c9b2cef9066927048c510b8fd29a40ed30ba6ff61
298 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The PDF contains a critical heuristic indicating a link to a known malicious redirector, disguised as a 'free generator / game hack'. This lure is further supported by a fake CAPTCHA prompt and brand impersonation (Apple). The document body, though heavily obfuscated, contains the malicious URL, suggesting the primary goal is to redirect the user to a potentially malicious site for credential harvesting or further exploitation.

Machine Learning

  • Nyx PDF Classifier clean score 0.0098

Heuristics 10

  • PDF links to a 'free generator / game hack' redirector critical PDF_GAME_HACK_REDIRECT_LURE
    PDF's clickable action targets a redirector of the form /app/<id>/<slug>-game-hack — the landing-page shape of a large SEO 'free spins / generator / game hack' lure family that funnels victims through rotating disposable hosts to a malware/scam payload. The multi-link variants also trip ML/link-farm rules; this catches the single-link variants that otherwise score clean. CRITICAL on its own: the /app/<id>/<slug>-game-hack path shape is unambiguous scam infra, and the host rotates so a host-list match can't be relied on.
  • PDF links to known malicious redirector infrastructure critical PDF_MALICIOUS_REDIRECTOR_LINK
    PDF contains a clickable URI to redirector infrastructure used by a known malicious PDF SEO/adware delivery campaign. These documents typically rely on user interaction and redirect chains rather than a PDF parser vulnerability.
  • Fake CAPTCHA / human verification prompt high SE_FAKE_CAPTCHA
    Document displays a fake CAPTCHA or human-verification prompt — used to trick users into running commands or pressing keyboard shortcuts
  • MFA / one-time-code harvesting lure high SE_MFA_LURE
    Document asks for a one-time code, authenticator approval, or MFA confirmation — consistent with credential phishing kits that steal session tokens or abuse multi-factor authentication
  • Brand-impersonation credential phishing lure high SE_BRAND_CREDENTIAL_PHISH
    Document impersonates a well-known consumer brand and uses account-security / verification language ('unusual activity', 'account on hold', 'verify your account') to steer the reader to a credential-harvesting link. Corroborated by: call-to-action link host does not match the impersonated brand: http://netcdn.tw/app/1330123889/pubg-uc-100-bonus-game-hack.
  • Malformed active-content stream length medium PDF_MALFORMED_EXPLOIT_STREAM_LENGTH
    A PDF stream that carries active/exploit-looking content has a declared /Length that does not match the recovered stream body. Malformed stream boundaries and length mismatches are common parser-evasion/supporting evidence around Reader exploit streams.
  • Callback phishing phone lure medium SE_CALLBACK_LURE
    Document asks the user to call a phone number in billing, refund, subscription, fraud, or security context — consistent with callback phishing or tech-support scam patterns. Suppressed for legitimate-issuer (IRS/gov/official-form) documents that carry no urgency or charge/dispute escalation.
  • Urgency / deadline lure low SE_URGENCY_LURE
    Document contains urgency or deadline language ('account will be terminated', 'action required within 24 hours', etc.) — useful context, but low-signal without other findings
  • Visual download / call-to-action button lure low SE_DOWNLOAD_BUTTON
    Document contains a call-to-action phrase ('Click here to download', 'Download Now', etc.) — low-signal unless other findings point to a malicious workflow
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://netcdn.tw/app/1330123889/pubg-uc-100-bonus-game-hack In PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/create-free-roblox-account_GM431946152.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/coin-master-official-fan-page_GM406889139.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/roblox-websites-that-give-free-robux_GM431946152.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/how-to-get-bc-for-free-roblox-2021_GM431946152.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/free-robux-generator-no-survey-no-download-no-human-verification_GM431946152.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/free-dungeon-hack-roblox_GM431946152.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/how-do-you-hack-your-roblox-account-site-youtubecom_GM431946152.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/free-coins-coin-master-iphone_GM406889139.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/get-free-spins-on-coin-master_GM406889139.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/free-robux-scam_GM431946152.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/free-robux-no-human-verification-or-survey_GM431946152.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/free-minecraft-capes_GM479516143.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/free-spins-coin-master-2021_GM406889139.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/how-to-hack-roblox-account-passwords_GM431946152.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/hacking-roblox-people_GM431946152.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/google-coin-master-free-spins_GM406889139.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/roblox-script-hacks_GM431946152.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/how-to-hack-roblox-accounts-on-phone_GM431946152.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/rbx-com_GM431946152.pdfIn PDF document text
    • http://www.nelsonssales.com/media/storage/editor/files/is-minecraft-free-on-ps4_GM479516143.pdfIn PDF document text
    • http://en.wikipedia.org/wiki/MIT_LicenseIn PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
stream_024_off00037fec.bin decompressed-pdf-stream PDF FlateDecoded stream at offset 0x37FEC 26180 bytes
SHA-256: 1827b3c87a1418543fb954fa8b735a4a81f6f0364700e7e6e5d42ae3e204739f
font_01_sfnt_off0003bd54.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x3BD54 18548 bytes
SHA-256: 9940b419c9d44e5eca6db426cfb8691f6fd3b114d5424fbc3ddd93fca3f065e6

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