RTF malware analysis — malicious · 28f4dfc5bcd904d3

MALICIOUS

RTF

1.63 MB First seen: 2021-06-30

MD5: 6c685fbac3ea03c42c51d61642c4e2df SHA-1: ade56c9990d060aa6bd0eb53be78f513db7263d3 SHA-256: 28f4dfc5bcd904d3e5f67424e54608a249414f0915ae4230ad12bc893d344343

220 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains multiple indicators of malicious activity, including embedded OLE objects and specific firings for CVE-2017-11882 related to Equation Editor exploitation. The presence of these elements strongly suggests the file is designed to exploit this known vulnerability for initial code execution. The extracted document body content appears to be obfuscated or malformed, providing no clear user-facing lure.

Heuristics 6

Split hex Equation Editor ProgID + OLE object critical CVE likely RTF_EQUATION_EDITOR

RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED

RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
\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.
Suspicious extracted artifact high 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.
OLE object data medium RTF_OBJDATA

RTF contains 2 \objdata section(s) — embedded OLE objects
Embedded OLE object medium RTF_OBJEMB

RTF contains \objemb — embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off000011e1.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x11E1	53990 bytes
SHA-256: `245ef1689a9c5a8b36ea4a40d9d1dbb1fa300841dcc107d685e3eb7e9d3af847`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): Wscript.ScriptFullName
`objdata_01_off0002fb33.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x2FB33	410074 bytes
SHA-256: `0a0103f81ecaf6eb904befe7f328952354a33a6d49f64b01ead02ee216cb69c4`

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