Malicious PDF — malware analysis report

Static analysis result for SHA-256 28f0cfabfcf0b99e…

MALICIOUS

PDF

34.7 KB Created: 2021-07-04 03:12:19 +07:00 Authoring application: wkhtmltopdf 0.12.6 (via Qt 4.8.7) First seen: 2021-09-13
MD5: 369abfa3bda626989f460c81066a1d93 SHA-1: e602832a0d6e8e33b6f8b3eb8bb2d377cfc7e0d8 SHA-256: 28f0cfabfcf0b99e15161fa213d0916f27176a85e216fef9426931545f6f842b
240 Risk Score

Malware Insights

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

The PDF contains malformed streams and links to known malicious redirectors, specifically advertising 'free robux' and 'game hacks'. The primary URL http://netcdn.tw/app/431946152/www-free-robux-com-game-hack is a critical finding, indicating a lure for potentially malicious content. The ML classifier also strongly flagged this PDF as malicious.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9980

Heuristics 6

  • 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.
  • Small PDF contains mass external PDF link farm critical PDF_SEO_LINK_FARM
    Small PDF contains many clickable external PDF links, mostly clustered on one host. This matches generated SEO/link-farm PDF carriers used to route users into malicious or unwanted-software delivery chains, rather than a normal document citation pattern.
  • 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 http://netcdn.tw/app/431946152/www-free-robux-com-game-hack In PDF document text
    • https://www.kaojen.com.tw/upload/files/how-to-get-free-robux-without-human-verification_GM431946152.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/pastebin-free-roblox-2021_GM431946152.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/free-robux-generator-no-survey-no-download-no-human-verification_GM431946152.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/wurst-115_GM479516143.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/free-roblox-outfits_GM431946152.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/how-to-hack-to-get-robux_GM431946152.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/how-to-download-minecraft-for-free-on-pc_GM479516143.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/how-to-hack-coins-in-roblox-mm2_GM431946152.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/free-robux-pc-no-survey-or-human-verification_GM431946152.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/how-you-get-free-robux_GM431946152.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/car-crushers-2-roblox-free_GM431946152.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/coin-master-free-spin-realme-products_GM406889139.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/aprender-a-hackear-cuentas-de-roblox_GM431946152.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/how-to-get-minecraft-realms-for-free_GM479516143.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/best-free-minecraft-server-hosting-reddit_GM479516143.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/roblox-images_GM431946152.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/free-pet-food-on-coin-master_GM406889139.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/how-to-go-through-everything-in-roblox-cheat-engine_GM431946152.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/how-to-hack-coin-master-without-root_GM406889139.pdfIn PDF document text
    • https://www.kaojen.com.tw/upload/files/free-robux-no-verification_GM431946152.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_002_off00002ea8.bin decompressed-pdf-stream PDF FlateDecoded stream at offset 0x2EA8 22804 bytes
SHA-256: aab8529b8b04a647a6f70f5bc0ad350224886b82f3734fa51053f14e002dd0af
font_01_sfnt_off000061c4.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x61C4 19336 bytes
SHA-256: a173ff8a3a1fb1a8f757a1ab0f7adc35a375ad8a6d6bf5003b7cfea3ec8bf678

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