Malicious PDF — malware analysis report

Static analysis result for SHA-256 661d548bcde3a612…

MALICIOUS

PDF

99.0 KB Created: 2021-09-04 15:20:23 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3)
MD5: d6f9ec526e5e7c8e33fb0f9c8aeba2fd SHA-1: 8abf686ffb64efc8e9e3a23225fa3a644099e242 SHA-256: 661d548bcde3a61279f88d0b6fe061546c3f40d52e8fc613d5bd72fb16dacb83
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

This PDF file was flagged by multiple heuristics and an ML classifier as malicious, with ClamAV identifying it as Pdf.Phishing.Trojan. The numerous embedded URLs point to compromised CMS uploads and disposable hosting, indicating a link farm designed to redirect users to malicious sites. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, suggesting it's not intended for human readability but rather as a container for malicious links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9953

Heuristics 6

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • 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 https://smidgel.ru/uplcv?utm_term=sci+index+journal+list+2019+pdf
    • https://purpleleafestatebuyers.com/wp-content/plugins/formcraft/file-upload/server/content/files/16074b513a27d5---zisexejewiwitupevekim.pdf
    • https://zlatartopalovic.rs//files/wasirenafigatizenapax.pdf
    • http://surmounttravel.com/userfiles/files/70021570780.pdf
    • http://ecohort.com/userfiles/files/punusame.pdf
    • https://baconbites.com/wp-content/plugins/super-forms/uploads/php/files/hsacohshmk80l098jv600ad8m5/kotatekidilorim.pdf
    • https://brylka-kfz.de/wp-content/plugins/formcraft/file-upload/server/content/files/160a4b151b270a---36947338080.pdf
    • https://retentionstudentexperience.com/wp-content/plugins/formcraft/file-upload/server/content/files/16099a94ecd617---metoj.pdf
    • https://pointvirgule.ca/upload/editor/file/buvitofupavodezoxared.pdf
    • https://dmvassociates.com/wp-content/plugins/super-forms/uploads/php/files/3d17f0fe396fab5e537cc30b4f0dec56/wikevag.pdf
    • http://accurateverdicts.com/wp-content/plugins/formcraft/file-upload/server/content/files/16096a4e578822---58569725936.pdf
    • https://binhruamuinanobac.com/wp-content/plugins/super-forms/uploads/php/files/25qssr4b6heg02iau2kdk5l97k/xojetilurakakiwegubixu.pdf
    • https://n95america.com/wp-content/plugins/super-forms/uploads/php/files/146894b26d87af4145ea15f3bf419df2/48902299519.pdf
    • http://lpc2529.com/piceditor/file/47977380106.pdf
    • http://pensjonatagat.pl/userfiles/file/42510162585.pdf
    • https://fietenhaardenenkachels.nl/wp-content/plugins/formcraft/file-upload/server/content/files/160f719202fc7d---16820249729.pdf
    • https://pragatitic.org/ckfinder/userfiles/files/biwunufiwamofa.pdf
    • https://wills.sg/wp-content/plugins/super-forms/uploads/php/files/45ec2a458a560970f113161cd1590359/nokedoxezav.pdf
    • https://www.chartsunlimited.com.ph/wp-content/plugins/formcraft/file-upload/server/content/files/1608c058898066---25920198281.pdf
    • http://superplasticizer.cn/d/files/19264236835.pdf
    • https://angkortaxiservice.com/userfiles/file/wosipezimapelozifud.pdf
    • http://romanakladatelstvi.cz/userfiles/file/3897191690.pdf
    • http://xn----7sbbbizu2bxaod.xn--p1ai/userfiles/file/vixozefazasopubig.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_off000114eb.bin
a62e9c3dfda657a74955f628ca931ab661f01fa49625fb6e28f27754b2b4eb59
pdf-font-stream PDF embedded font (sfnt) at offset 0x114EB 11480 bytes
font_01_sfnt_off00013049.bin
9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
pdf-font-stream PDF embedded font (sfnt) at offset 0x13049 16792 bytes
font_02_sfnt_off0001485b.bin
1737935dc2dcc9f4e4906067bd9867f7c5c20cf0bc122830f0f17f2b7d970517
pdf-font-stream PDF embedded font (sfnt) at offset 0x1485B 20532 bytes