Malicious PDF — malware analysis report

Static analysis result for SHA-256 d99b53083d805c85…

MALICIOUS

PDF

67.0 KB Created: 2021-09-27 09:51:56 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-11-25
MD5: ea652bb014d476b6a75910c803263cb4 SHA-1: 0784c9e38ebcaf575ee1363ed1a4043b019e64cf SHA-256: d99b53083d805c85e365a3dcaf3d2137613038554f3c50ff8da3b0cf64c7b48e
176 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The sample is identified as malicious by ML classifiers and ClamAV, with heuristics indicating it's a callback phishing lure. Although no scripts were explicitly extracted, the PDF structure and embedded URLs suggest an attempt to direct users to potentially malicious content or services. The presence of multiple links, some hosted on compromised CMS uploads and disposable domains, further supports a phishing or scam-related attack pattern.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9993

Heuristics 7

  • 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.
  • Callback phishing phone lure medium SE_CALLBACK_LURE
    Document asks the user to call a phone number in billing, refund, subscription, fraud, or security context — consistent with callback phishing or tech-support scam patterns. Suppressed for legitimate-issuer (IRS/gov/official-form) documents that carry no urgency or charge/dispute escalation.
  • 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://mertcelikkapi.com/userfiles/file/78037775642.pdf In PDF document text
    • http://bighost.vn/uploads/userfiles/file/72061649426.pdfIn PDF document text
    • https://bem-sa.com/img/file/62644805340.pdfIn PDF document text
    • http://msdoubrava.cz/foto/images/file/naxekukufukiwowowaxijibo.pdfIn PDF document text
    • http://dbexpertise.fr/catalogue_dynamique/file/71838285321.pdfIn PDF document text
    • http://sh8ke.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613fdac135491---93350592970.pdfIn PDF document text
    • https://groupburuemas1.com/contents/files/gadinamidux.pdfIn PDF document text
    • http://vetranhtuong.info/luutru/files/41023118377.pdfIn PDF document text
    • http://energywork.pl/userfiles/file/leviluxejawunikelorinuki.pdfIn PDF document text
    • http://www.contal-farmer.com/uploads/files/17973391865.pdfIn PDF document text
    • http://snookerfootball.eu/wp-content/plugins/formcraft/file-upload/server/content/files/1614a1322d0379---58415200765.pdfIn PDF document text
    • http://www.nationaalgolfcongres.nl/wp-content/plugins/formcraft/file-upload/server/content/files/1613cd019def0b---kagimiwifiwogurarasi.pdfIn PDF document text
    • http://opusbiz.kr/data/editor/file/529545859613a00176383c.pdfIn PDF document text
    • http://scenekunstskolen-efteruddannelsen.dk/ckfinder/userfiles/files/3549489300.pdfIn PDF document text
    • http://laboratoriologos.it/userfiles/files/62242245378.pdfIn PDF document text
    • http://esoftland.com/userfiles/file/sifuvatefij.pdfIn PDF document text
    • http://statsale.com/data/upload/ck/files/4182930427.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/DOqCt-cVA4I/uplcv?utm_term=identifying+prime+and+composite+numbersPDF 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_off0000a8b2.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xA8B2 14472 bytes
SHA-256: a2e17c3119692879b9e0b653703e697d87e49bd73723d649b409e30d7f5dfbc3
font_01_sfnt_off0000ccf8.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xCCF8 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off0000e50f.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE50F 11224 bytes
SHA-256: ec1aa35a0edc1e7483d2f7eae820c97de639662ae702ca96b77fbc3a3a5937e2