RTF / .DOC malware analysis — malicious · e9f3ac58cfc9bff9

MALICIOUS

RTF / .DOC

1.15 MB First seen: 2021-10-31

MD5: c696dababa4bbf5c3ac937b8fbf4f3be SHA-1: bb15f71e04edee2970e6431ba29e08de225c735b SHA-256: e9f3ac58cfc9bff9e545094754021380951c89eaf20564305e5be37a91e306d1

222 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF document contains an OLE object with data indicative of the Equation Editor vulnerability, CVE-2017-11882. The presence of ".objdata" sections and ".objupdate" directives strongly suggests that the embedded object is designed to be activated, likely leading to the execution of a second-stage payload. The high entropy and size of the decoded OLE object further support the presence of a hidden executable.

Heuristics 6

Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED

RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact attribution was not recovered.
Split hex Equation Editor ProgID + OLE object critical 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.
\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.
Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX

RTF contains ~1209KB of hex-encoded data inside \objdata sections — may hide a payload
OLE object data medium RTF_OBJDATA

RTF contains 2 \objdata section(s) — embedded OLE objects
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 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off000000c0.bin` `56bc0f3f43e75ac1d0442e2b2ff1587a5fdb61a4b2b62436bfb04ee634e182c0`	rtf-objdata-decoded	RTF \objdata at offset 0xC0	605024 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 8.00, consistent with packed or encrypted content.

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