Malicious PDF — malware analysis report

Static analysis result for SHA-256 b905032689fe8e84…

MALICIOUS

PDF

79.3 KB Created: 2021-09-19 02:49:13 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-16
MD5: c281f84ae57c99bea24ed5555520934e SHA-1: 4987183161542558753666299e991be317c6e33c SHA-256: b905032689fe8e84d221ef7ac9cbe8cdff8b04ae0c04e6cf8c697c33575ca00b
96 Risk Score

Malware Insights

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

The sample was identified as malicious by an ML classifier and exhibits characteristics of a link farm. Multiple heuristics indicate the PDF contains numerous links pointing to external resources, many hosted on compromised CMS upload directories. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, suggesting it's not intended for direct user consumption but rather as a vehicle for distributing links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9953

Heuristics 5

  • 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://agama-rc.com/upload/files/36925684312.pdf In PDF document text
    • http://ailizia.com/userfiles/91890761910.pdfIn PDF document text
    • https://noddy.nu/images/file/wimewolinura.pdfIn PDF document text
    • https://gea99.com/ckfinder/userfiles/files/basujezoked.pdfIn PDF document text
    • http://tubemakingmachine.com/uploadfile/files/2497106765.pdfIn PDF document text
    • http://www.uppld.org/wp-content/plugins/formcraft/file-upload/server/content/files/16139dbd3c2b14---6557923804.pdfIn PDF document text
    • http://medicalproduct.hu/images/files/wafew.pdfIn PDF document text
    • http://www.dfdtrading.sk/ckfinder/userfiles/files/59307139848.pdfIn PDF document text
    • http://cbstav.cz/file/tedisokawigujebibetiniw.pdfIn PDF document text
    • http://gf-location.fr/wp-content/plugins/formcraft/file-upload/server/content/files/1613627f8dfd87---35931805771.pdfIn PDF document text
    • http://sys-svinding.dk/userfiles/file/jitowogumuwuwoxalixiwiba.pdfIn PDF document text
    • http://gps-tw.com/CKEdit/upload/files/71116643751.pdfIn PDF document text
    • http://deurenhanger.nl/userfiles/file/72901226342.pdfIn PDF document text
    • https://aymsoft.us/aym_image/files/paburele.pdfIn PDF document text
    • http://koryosushi.com/uploads/files/lebaw.pdfIn PDF document text
    • http://xn--hh0b97d8is16e.com/userData/board/file/zalovodetasov.pdfIn PDF document text
    • http://at2apigroup3.com/contents/files/rebutubusufumomupeposiso.pdfIn PDF document text
    • https://maintogelonline.info/contents/files/33504448217.pdfIn PDF document text
    • http://caacoding.net/wp-content/plugins/formcraft/file-upload/server/content/files/1613130c72b872---sifolu.pdfIn PDF document text
    • http://ecompletecontact.com/ckfinder/userfiles/files/newigepibubaruv.pdfIn PDF document text
    • https://safewatersolutions.in/ckfinder/userfiles/files/60735007146.pdfIn PDF document text
    • https://liho.cz/UserFiles/File/67790591504.pdfIn PDF document text
    • http://indiebookoftheday.com/wp-content/plugins/formcraft/file-upload/server/content/files/16132101a05604---19025295573.pdfIn PDF document text
    • http://geasit.it/userfiles/files/34302852948.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/BkSY9tpko7c/uplcv?utm_term=movie+hd+online+apkPDF link annotation
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#In PDF document text
    • http://purl.org/dc/elements/1.1/In PDF document text
    • http://ns.adobe.com/pdf/1.3/In PDF document text
    • http://ns.adobe.com/xap/1.0/In PDF document text
    • http://ns.adobe.com/xap/1.0/mm/In PDF document text
    • http://ns.adobe.com/xap/1.0/rights/In PDF document text
    • http://dejavu.sourceforge.netIn PDF document text
    • http://dejavu.sourceforge.net/wiki/index.php/LicenseIn PDF document text

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000d4e3.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD4E3 17272 bytes
SHA-256: d7ee3b6f3d974b6a89384ceddb0fe040a4176027cb799e54e96667349a1a00c3
font_01_sfnt_off00010103.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10103 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off0001191a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1191A 10276 bytes
SHA-256: df7a1f4e6315f1467a2c88e96225d3b439f1a9612fb3196d59037cec62dfdcaa