Malicious PDF — malware analysis report

Static analysis result for SHA-256 c0959a8db2d1d0a4…

MALICIOUS

PDF

7.8 KB
MD5: 6cb87ec9a2e705869aafeb0d3eb0c418 SHA-1: e7120bcc768c5ef50ad7448bd66ea44227816617 SHA-256: c0959a8db2d1d0a4229766cf0c8e046c868b85b1178c26e1b8579ae74c9a4d7d
134 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell

The critical ClamAV detection and high-severity heuristic for an obfuscated multi-stage PDF JavaScript dropper indicate a malicious PDF. The embedded JavaScript, particularly the deobfuscated.js artifact, likely decodes and executes a second-stage payload. The obfuscation techniques and the nature of the dropper suggest a downloader or exploit delivery mechanism.

Heuristics 7

  • ClamAV: Pdf.Exploit.Agent-35916 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-35916
  • 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
6c41320119e160dc719997b9a2efb3600ea9d7e9d7e44b4dc2125762dc9f365f
pdf-javascript-stream PDF /JS object 5 at offset 0x148 505 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
legacy_pdfkit_stage_000.js
e4a92001ea1a64c22ffdc8f2fb2c016fc1dfb469870dcf0b4320222aa6172f45
deobfuscated-js repeated-marker hex decoded JavaScript at offset 0x1A21 1673 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
deobfuscated.js
2d44b80679672fed8ee5c0d556b1f1e9a7e58e936b1b82fb8004e64ecd786a63
deobfuscated-js PDF JavaScript deobfuscation pass 22620 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 7 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).