Malicious PDF — malware analysis report

Static analysis result for SHA-256 9c157a11eecd02fa…

MALICIOUS

PDF

7.9 KB
MD5: 01f47bc74ff5c8beee21ae417de5c30e SHA-1: 0acb6b558bbc9ef498dff67e0c4079ca000ee66c SHA-256: 9c157a11eecd02fa36a930b35813a1c09fbf6675d4e609f60100d6e3bcd0c6b1
134 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell

The PDF contains heavily obfuscated JavaScript, identified by heuristics as a multi-stage dropper. This script is designed to decode and execute a secondary payload, likely for further system compromise. The ClamAV detection 'Pdf.Exploit.Agent-35902' further confirms its malicious nature. The primary attack vector involves exploiting PDF vulnerabilities to run arbitrary code.

Heuristics 7

  • ClamAV: Pdf.Exploit.Agent-35902 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-35902
  • Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER
    PDF JavaScript shows 5 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, hex_codec_loop, hex_dashed_payload, incremental_eval_build, repeated_pluginschk. This is strongly consistent with pre-2011 Adobe Reader PDF droppers — OpenAction JS reads encoded data from annotation subjects, decodes it through one or more hex / base-N loops, and invokes eval indirectly (method name built one character at a time). The actual CVE is hidden in the final decoded layer and is not visible via static analysis.
  • 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.
  • String.fromCharCode low PDF_FROMCHARCODE
    String.fromCharCode found — used to construct payload strings dynamically. Common in benign JavaScript libraries for codepoint manipulation, so this alone is informational; weaponised use is also caught by the dedicated fromCharCode-stage and exploit-shape rules. (matched inside decoded stream)
  • syncAnnotScan annotation-staging primitive low PDF_FOXIT_SYNCANNOTSCAN
    PDF JavaScript calls syncAnnotScan() — a no-op annotation-enumeration primitive used by exploit-kit JavaScript to stage payload reads from annotation /Subject fields before eval(). Not a vulnerable sink itself; rarely seen in legitimate PDFs. (matched in decompressed stream)
  • 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.

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0005_000.js
3cf6a22459cda11e607fc9e0dc0c88d01a8425e26488ff87df38d855ceb4dccf
pdf-javascript-stream PDF /JS object 5 at offset 0x148 465 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
legacy_pdfkit_stage_000.js
fe2a0fc35ec28d98815a98d2728fa0d94841288e956bc38b11c61fb893cb06d9
deobfuscated-js repeated-marker hex decoded JavaScript at offset 0x1A75 1763 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
deobfuscated.js
30d5991450531c713c59de59c9ab2fdc6b5dad1b5351e199aa7ff334bd78deb2
deobfuscated-js PDF JavaScript deobfuscation pass 22353 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 5 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).