Malicious PDF — malware analysis report

Static analysis result for SHA-256 b40ef2c80e402dc5…

MALICIOUS

PDF

47.0 KB Created: 2021-06-08 14:54:50 +07:00 Authoring application: wkhtmltopdf 0.12.6 (via Qt 4.8.7) First seen: 2021-10-27
MD5: 13c62283091fd227ec3aa33d610d04a7 SHA-1: f8924437d0a9628585e64eac4df4a0e51c239168 SHA-256: b40ef2c80e402dc583167ada4e4829972922d5e6fa727a298635dfa4a24f6cfc
180 Risk Score

Malware Insights

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

The PDF contains a malformed stream and links to known malicious redirector infrastructure, specifically advertising a "free generator / game hack". The primary lure URL is https://netcdn.tw/app/431946152/free-robux-no-human-verification-or-offers-game-hack, which is designed to trick users into clicking through to potentially malicious sites. The ML classifier also flagged this PDF with high confidence.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9832

Heuristics 5

  • 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.
  • 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.
  • 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 https://netcdn.tw/app/431946152/free-robux-no-human-verification-or-offers-game-hack In PDF document text
    • http://library.atim.ac.id/repository/free-robux-with-no-human-verification_GM431946152.pdfIn PDF document text
    • http://library.atim.ac.id/repository/free-spins-and-coins-coin-master-2021-link_GM406889139.pdfIn PDF document text
    • http://library.atim.ac.id/repository/coin-master-time-hack_GM406889139.pdfIn PDF document text
    • http://library.atim.ac.id/repository/how-do-you-get-free-robux-without-doing-anything_GM431946152.pdfIn PDF document text
    • http://library.atim.ac.id/repository/free-spin-coin-master-2021-link_GM406889139.pdfIn PDF document text
    • http://library.atim.ac.id/repository/free-minecraft-account_GM479516143.pdfIn PDF document text
    • http://library.atim.ac.id/repository/how-to-get-free-robux-website_GM431946152.pdfIn PDF document text
    • http://library.atim.ac.id/repository/roblox-free-vip-server_GM431946152.pdfIn PDF document text
    • http://library.atim.ac.id/repository/free-robux-no-human-verification-or-survey-2021_GM431946152.pdfIn PDF document text
    • http://library.atim.ac.id/repository/how-to-get-free-robux-without-verifying_GM431946152.pdfIn PDF document text
    • http://library.atim.ac.id/repository/offer-for-pubg-uc_GM1330123889.pdfIn PDF document text
    • http://library.atim.ac.id/repository/free-tiktok-followers-instantly_GM835599320.pdfIn PDF document text
    • http://library.atim.ac.id/repository/how-to-get-free-robux-2021_GM431946152.pdfIn PDF document text
    • http://library.atim.ac.id/repository/get-me-free-robux_GM431946152.pdfIn PDF document text
    • http://library.atim.ac.id/repository/how-to-get-a-free-dominus-in-roblox_GM431946152.pdfIn PDF document text
    • http://library.atim.ac.id/repository/coin-master-hack-spins-free_GM406889139.pdfIn PDF document text
    • http://library.atim.ac.id/repository/free-tiktok-fans-no-human-verification-or-downloading-apps_GM835599320.pdfIn PDF document text
    • http://library.atim.ac.id/repository/free-robux-mod_GM431946152.pdfIn PDF document text
    • http://library.atim.ac.id/repository/free-tiktok-likes-generator_GM835599320.pdfIn PDF document text
    • http://library.atim.ac.id/repository/free-minecraft-server-hosting-24-7_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_004_off0000559e.bin decompressed-pdf-stream PDF FlateDecoded stream at offset 0x559E 26776 bytes
SHA-256: 87e8eed92fafd1fcb9426bd55b970d37e5bb2ccd82d8ce57768b3340c7b1b501
font_01_sfnt_off00009371.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x9371 18860 bytes
SHA-256: 284e47a4945fe51d45e8a78457859f490c594006d3228e23a92412e1c9bc466e

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