Malicious PDF — malware analysis report

Static analysis result for SHA-256 f580d14f6468bf48…

MALICIOUS

PDF

16.6 KB
MD5: 2bedf1df460188758132cbff8a47c8f4 SHA-1: c4ce67ccbba54c5133189b05cd358b2f2d0d51fd SHA-256: f580d14f6468bf48a511c1c7206ab7ba690e3aab832bec2a34bb28716059b150
194 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 JavaScript/JScript T1204.001 Malicious Link/Object

The PDF file contains obfuscated JavaScript, identified as a multi-stage dropper. Static analysis detected the use of CVE-2007-5659, specifically the Collab.collectEmailInfo sink, which is a known method for exploiting Adobe Reader vulnerabilities. The JavaScript is heavily obfuscated using techniques like String.fromCharCode with hex decoding and incremental method name building, indicating an attempt to evade detection. The primary function of the script is to download and execute a second-stage payload, as evidenced by the dropper heuristic and the presence of deobfuscated JavaScript streams.

Heuristics 8

  • Collab.collectEmailInfo — CVE-2007-5659 critical CVE exact CVE_2007_5659
    PDF JavaScript calls Collab.collectEmailInfo — CVE-2007-5659 is a buffer overflow in Adobe Reader triggered by a long argument or heap-sprayed message field passed to Collab.collectEmailInfo(). Part of a series of Acrobat JS API exploits. (identified after JavaScript deobfuscation)
  • ClamAV: Pdf.Exploit.Agent-35901 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-35901
  • Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER
    PDF JavaScript shows 4 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, hex_codec_loop, 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_obj0009_000.js
4718a27c2224fc36bf24f8e8e04598f1ad78adce4401c7be2708318738a6983d
pdf-javascript-stream PDF /JS object 9 at offset 0x3FFE 469 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
94175ca89bdebaff80f5683cd5323cd19bb91c3caae8de79c670dbba19db7147
deobfuscated-js z-percent UTF-16BE base-21 decoded JavaScript at offset 0x1969 5014 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 5 eval/decoder/string-building token(s).
deobfuscated.js
49edddf7577953bbed0ef80d24ae77f004944892f2fd000886e638604b97acea
deobfuscated-js PDF JavaScript deobfuscation pass 113380 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 4 eval/decoder/string-building token(s). Carved artifact contains 2 long base64-like blob(s).