Malicious PDF — malware analysis report

Static analysis result for SHA-256 83a4a1b5bdab131c…

MALICIOUS

PDF

45.3 KB
MD5: db8e83e99be5bbbeb50a4773a67be5de SHA-1: 42c6bed9f69d473a9774c33163f1bb58ea10248c SHA-256: 83a4a1b5bdab131cf272f72dbf89ffbf4405afc0c1c113d1a3fb158e2614c53b
306 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.007 JavaScript

This PDF file is identified as malicious due to critical heuristic firings indicating an exploit for Adobe Reader (CVE-2010-2883) and embedded JavaScript. The JavaScript, obfuscated using unescape, likely serves as a dropper for a second-stage payload. The presence of XFA forms and the ML classifier further support its malicious nature.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9993

Heuristics 11

  • Adobe Reader CoolType SING font exploit — CVE-2010-2883 critical CVE likely CVE_2010_2883
    PDF embeds a TrueType/OpenType font with an actual SING table and pairs it with JavaScript heap-spray shellcode. This matches the public Adobe Reader CoolType SING exploit shape for CVE-2010-2883.
  • PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER
    PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
  • ClamAV: Pdf.Dropper.Agent-7278166-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Dropper.Agent-7278166-0
  • unescape() call high PDF_UNESCAPE
    unescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
  • Embedded script payload in PDF stream medium PDF_EMBEDDED_SCRIPT_PAYLOAD
    PDF stream bytes contain an HTML/XFA <script> tag without accompanying Windows shell-execution primitives — common in accessible XFA forms but worth surfacing for analyst review.
  • JavaScript action low PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • Embedded JS stream low PDF_JS
    PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • XFA form low PDF_XFA
    PDF uses XML Forms Architecture — can contain script logic
  • AcroForm button with action trigger low PDF_ACROFORM_BUTTON
    PDF contains a /Btn form field together with a SubmitForm/URI/Launch/JS trigger — this is the building block of fake 'Download' or 'Open' button overlays used in PDF phishing lures
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • 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://www.bitstream.com
    • http://ns.adobe.com/xdp/
    • http://www.xfa.org/schema/xci/3.0/
    • http://www.xfa.org/schema/xfa-template/3.0/
    • http://www.xfa.org/schema/xfa-data/1.0/

Extracted artifacts 5

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0001_000.js
b52a3e8b5384af2dde6c1c791f0f533cda07dbc9a43294d726f2e26943c5de3f		 pdf-javascript-stream PDF /JS object 1 at offset 0xA 2229 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
stream_002_off0000abdd.js
d1dfd457a2fdd3cec4091f689f39b85b35666aa5599ef3a8d5f9a80d1e2ce105		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0xABDD 1042 bytes
font_00_sfnt_off00000e27.bin
0a9d80eb5035eebb0c10270efed77a3c0db964fa2531769c099ff8a900566e58		 pdf-font-stream PDF embedded font (sfnt) at offset 0xE27 65932 bytes
font_01_type1_off0000b081.bin
c6bf78478c9c4dd5b3b86554d34c78f847f70af4118f9ff083c1fccf0e8e932b		 pdf-font-stream PDF embedded font (type1) at offset 0xB081 97 bytes
font_02_type1_off0000b30a.bin
b749644b3e758e7335900ab2e7499eaa64b3a946849f1f8a0948287bdd96763d		 pdf-font-stream PDF embedded font (type1) at offset 0xB30A 144 bytes

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