Malicious PDF — malware analysis report

Static analysis result for SHA-256 90829e8af3baaeea…

MALICIOUS

PDF

42.7 KB Created: 2021-05-14 11:46:25 +07:00 Authoring application: wkhtmltopdf 0.12.6 (via Qt 4.8.7) First seen: 2021-10-31
MD5: c050fdb04e2dc346f512c90d7be1363d SHA-1: cc98242bb3834e8b2702b933771df58991d210ec SHA-256: 90829e8af3baaeea0324c882f940bed27d43a37768146b1c2db27f997517ddfb
220 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 User Execution: Malicious File

The PDF contains a fake CAPTCHA lure and links to known malicious redirectors, specifically promoting "free generators" and "game hacks" for popular online games. The malformed stream length heuristic and ML classifier indicate malicious intent. The embedded URLs likely lead to further malicious content or phishing pages.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9977

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.
  • 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
  • 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.xyz/app/431946152/free-roblox-account-generator-game-hack In PDF document text
    • http://razredna-nastava.net/files/free-robux-generator-no-human-verification-2021_GM431946152.pdfIn PDF document text
    • https://razredna-nastava.net/files/robloxheroxyz-free-robux_GM431946152.pdfIn PDF document text
    • http://razredna-nastava.net/files/how-do-you-get-free-robux-2021_GM431946152.pdfIn PDF document text
    • http://razredna-nastava.net/files/free-spin-appscoin-master_GM406889139.pdfIn PDF document text
    • http://razredna-nastava.net/files/coin-master-free-spins-hack-without-human-verification_GM406889139.pdfIn PDF document text
    • https://razredna-nastava.net/files/free-spin-coin-master-2021-link_GM406889139.pdfIn PDF document text
    • http://razredna-nastava.net/files/coin-master-free-spin-link-new_GM406889139.pdfIn PDF document text
    • http://razredna-nastava.net/files/roblox-hack-game_GM431946152.pdfIn PDF document text
    • https://razredna-nastava.net/files/free-robux-obby-2021_GM431946152.pdfIn PDF document text
    • https://razredna-nastava.net/files/free-roblox-com_GM431946152.pdfIn PDF document text
    • http://razredna-nastava.net/files/coin-master-golden-card-hack_GM406889139.pdfIn PDF document text
    • http://razredna-nastava.net/files/free-robux-download_GM431946152.pdfIn PDF document text
    • http://razredna-nastava.net/files/robux-free-online_GM431946152.pdfIn PDF document text
    • http://razredna-nastava.net/files/how-to-get-free-coins-on-coin-master-hack_GM406889139.pdfIn PDF document text
    • https://razredna-nastava.net/files/how-to-get-minecraft-for-free-on-xbox-one_GM479516143.pdfIn PDF document text
    • http://razredna-nastava.net/files/level-coin_GM406889139.pdfIn PDF document text
    • https://razredna-nastava.net/files/apps-that-give-you-free-robux_GM431946152.pdfIn PDF document text
    • https://razredna-nastava.net/files/link-for-free-spins-on-coin-master_GM406889139.pdfIn PDF document text
    • http://razredna-nastava.net/files/coin-master-free-online-game_GM406889139.pdfIn PDF document text
    • http://razredna-nastava.net/files/send-me-500-2021-spins_GM406889139.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_003_off00004a1b.bin decompressed-pdf-stream PDF FlateDecoded stream at offset 0x4A1B 25172 bytes
SHA-256: e0600ea429d1ade4e73abdabaab43ae2b5dad8abf4a66b5035faa78cea3f9783
font_01_sfnt_off00008421.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x8421 18420 bytes
SHA-256: 7ac5e27b34c4b1ad8a7b5cb593be6d3cc1f904c1acada5288a93079ea3be41d7

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