Malicious PDF — malware analysis report

Static analysis result for SHA-256 ed58e5c4d88fc74e…

MALICIOUS

PDF

8.1 KB
MD5: b568700df13114206b10b32721baa400 SHA-1: c0e168e86142450c72904251a79ac18b4fb1d170 SHA-256: ed58e5c4d88fc74e9dcd6525f97d709ad9cbe4ef224db2fb66a9ad0bb8f28651
134 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.001 Malicious Link T1071.001 Web Protocols T1566.002 Spearphishing Attachment T1204.002 Malicious File

The PDF file contains obfuscated JavaScript, identified as a multi-stage dropper. It leverages the CVE-2007-5659 vulnerability, specifically using the `Collab.collectEmailInfo` method to decode and execute a payload. The script performs anti-analysis checks by verifying `app.plugIns.length`. The deobfuscated JavaScript suggests a complex dropper mechanism designed to download and execute further stages, although the final payload and its destination are not directly evident from the static analysis.

Heuristics 7

  • 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)
  • Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER
    PDF JavaScript shows 3 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, hex_dashed_payload, 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 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0005_000.js
9d5c7e01faed5b04e9ec11f1d98b73f0012c871beaf60e9f9d32ad6df00d46f7
pdf-javascript-stream PDF /JS object 5 at offset 0x148 550 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
abf7a85b746106fe01aa36d3fbe254d451d55a608641d827c3d2cb957c919b1a
deobfuscated-js repeated-marker hex decoded JavaScript at offset 0x1AFD 1868 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
legacy_pdfkit_stage_001.js
3a23dccbb57f6132b6393e6b6931616cfca5035c60a52570c6ba6ed1cdddab4a
deobfuscated-js annotation-subject callee-key decoded JavaScript at offset 0x359 4957 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 5 eval/decoder/string-building token(s).
deobfuscated.js
d86f70e24bdc19ce429edaf49a184fb98503195b818017d0ea675787643b4d91
deobfuscated-js PDF JavaScript deobfuscation pass 21174 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).