RTF malware analysis — malicious · 1fb37b8e7914f5f7

MALICIOUS

RTF

1.79 MB First seen: 2021-07-13

MD5: ef620dbae086ab5ce901c27323a0cb31 SHA-1: 3322051a3d8037522eba6fbefe5986c40154c9a1 SHA-256: 1fb37b8e7914f5f7b12921f8b26930b3f33ba0963beb1e360b07f069909f5736

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 OLE object data and specific heuristics pointing to the Equation Editor vulnerability (CVE-2017-11882). This vulnerability is known to be exploited for client execution, likely to deliver a secondary payload. The presence of decoded object data further supports the exploitation of this known vulnerability.

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	61489 bytes
SHA-256: `249759f1cc698ed36a925fc66d60c596de8e49e3b54c184880d66401da74efdc`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): WScript.ScriptName, WScript.Quit(), Cmd = strActivationID(""" ypoc c/ dmc") & sKeys & WScript.ScriptName & """ """ & lValue & """ /Y"
`objdata_01_off00034cdc.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x34CDC	453383 bytes
SHA-256: `4d6664f118eedff717160ab4a66190ef5c19c482cce6369b56962aafb643a777`

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