Malicious PDF — malware analysis report

Static analysis result for SHA-256 21be4f7507570d3f…

MALICIOUS

PDF

80.5 KB Created: 2021-09-07 13:49:00 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3)
MD5: 9b46f350eb5be3f60b8d740b68a37dc6 SHA-1: c36c697ea5ebad9add6f19b9b6c67287144fc06c SHA-256: 21be4f7507570d3fecff9964f5e38a120bbc0b07edac1f56b80aac370aa9af36
196 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The file was detected as malicious by ClamAV and an ML classifier, and exhibits characteristics of a link farm pointing to compromised WordPress upload storage. The embedded URLs are likely used to redirect users to malicious sites, potentially for phishing or to download further payloads. No scripts were extracted, but the PDF structure itself facilitates the redirection.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9991

Heuristics 7

  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • PDF link to algorithmically-generated URL high PDF_RANDOM_URL_LINK
    PDF contains a clickable HTTP(S) link whose host looks algorithmically generated (pronounceable-random labels) and whose path/query carries a long high-entropy token. This is the randomized-redirector pattern of malspam phishing lures — the visible document is only a prompt — not a PDF parser vulnerability.
  • PDF link farm points to compromised-WordPress upload storage medium PDF_COMPROMISED_CMS_UPLOAD_LINK_FARM
    PDF contains multiple clickable links, across many distinct hosts, whose targets are random-slug files parked in the upload directories of vulnerable WordPress form plugins (FormCraft, Super Forms). This is the hallmark of the 'free document/template' SEO phishing PDF family, which ranks for search queries and routes users into payload/redirect chains hosted on compromised sites. The PDF itself carries no exploit — the risk is the linked destinations.
  • Small PDF is a non-clustered link farm on disposable hosting medium PDF_SEO_DISPOSABLE_LINK_FARM
    Small PDF contains many clickable external PDF links spread thin across many distinct hosts (no single dominant host), corroborated by a utm_term SEO-redirector link and/or links parked on free/disposable content hosts. This is the 'free document/template' SEO phishing PDF family, which ranks for search queries and routes users into payload/redirect chains, rather than a normal document citation pattern. The PDF itself carries no exploit — the risk is the linked destinations.
  • External URI info PDF_URI
    PDF contains an external URL action
  • Object number defined twice with different bodies info PDF_DUPLICATE_OBJ_BODY_INCREMENTAL
    The same indirect object (N G) is defined more than once with different body bytes. First-wins and last-wins readers will resolve different content, which is a parser-confusion shape used by targeted PDFs. Body-only differences are common in benign incremental updates, so severity is raised only when the duplicate carries active content.
  • 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://doublehappyvstheinfinitesadness.com/wp-content/plugins/formcraft/file-upload/server/content/files/160a1ddeee8224---81278341227.pdf
    • http://kibunajcc.com/ckfinder/userfiles/files/49797759245.pdf
    • http://www.1000ena.com/wp-content/plugins/formcraft/file-upload/server/content/files/160bd8c8489c21---31418674311.pdf
    • http://krindustria.com.br/site/wp-content/plugins/formcraft/file-upload/server/content/files/160b6e612b28c2---62809824460.pdf
    • http://m2m2design.com/userfiles/31770004967.pdf
    • https://thealloywheelcentre.co.uk/wp-content/plugins/super-forms/uploads/php/files/98aac17f4aba98e307c80fdd342ab9e0/tujeniwajol.pdf
    • https://www.ideakliniksisli.com/wp-content/plugins/formcraft/file-upload/server/content/files/160d79f94bb77a---14939446915.pdf
    • http://esistore.be/userfiles/file/posijokoxanebodedejibegej.pdf
    • http://bjoybrands.com/wp-content/plugins/formcraft/file-upload/server/content/files/1609da5fe43d52---35897733704.pdf
    • http://danguykhoidoanhnghiephp.vn/Upload/files/55760211951.pdf
    • https://pluviaterra.mx/wp-content/plugins/super-forms/uploads/php/files/5a31ae18480472008ab80a8c3c66d99e/10391694181.pdf
    • https://xn--80aesyq.xn--p1ai/files/file/paxululap.pdf
    • https://useoneconvo.com/wp-content/plugins/super-forms/uploads/php/files/5afc798812231417337d64851031c0ca/44633721412.pdf
    • https://qualitycountscleaning.com/wp-content/plugins/super-forms/uploads/php/files/b1b0c880627bd59a41fd3bb1dbd1f9b5/zenol.pdf
    • https://classykitchen.pl/web/uploads/files/81342914227.pdf
    • https://playgametoday.ru/wp-content/plugins/super-forms/uploads/php/files/d80c77460736bc67008dbb95747b6025/samopepuveso.pdf
    • https://trsbarriersdirect.com/wp-content/plugins/super-forms/uploads/php/files/ike5b38q28n6d8bnv8ju17sop8/43617158205.pdf
    • https://hkbca.org/UploadFiles/file/20210624041446138.pdf
    • https://rosewoodcity.org/nbloom/fckuploads/file/37610280807.pdf
    • http://steinemann-ag.ru/10527172909.pdf
    • https://feedproxy.google.com/~r/skout/mBVl/~3/1xuhb7AK25c/uplcv?utm_term=notice+and+note+signposts+fiction+pdf
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/pdf/1.3/
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/rights/
    • http://dejavu.sourceforge.net
    • http://dejavu.sourceforge.net/wiki/index.php/License

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000d68c.bin
e07469f7a99e5c38fcf2c2643b55732442848d02435e2adc2e17e9517df5706b
pdf-font-stream PDF embedded font (sfnt) at offset 0xD68C 10624 bytes
font_01_sfnt_off0000eecb.bin
9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
pdf-font-stream PDF embedded font (sfnt) at offset 0xEECB 16792 bytes
font_02_sfnt_off000106dd.bin
952bcb8738b1f1d1d424b89aa532b3d1357b7fd2074a858d4f2415ecd64085c7
pdf-font-stream PDF embedded font (sfnt) at offset 0x106DD 17416 bytes