RTF malware analysis — malicious · f015853dcbb3f977

MALICIOUS

RTF

837.6 KB First seen: 2020-05-25

MD5: b12872583f39a519234a0f7a603dfc47 SHA-1: e04f8837ce90357d1b6344026cb6ac5da62e47ae SHA-256: f015853dcbb3f977b20ccf503ca5b2fbcc6e191cf6c275d8cfd4c2751df29b33

280 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is an RTF document that contains an embedded OLE object exploiting the CVE-2017-11882 vulnerability in Microsoft Equation Editor. This vulnerability allows for the execution of arbitrary code, which in this case is a PE file. ClamAV detection confirms this is a known dropper.

Heuristics 7

Decoded Equation Editor payload + PE critical CVE likely RTF_EQUATION_EDITOR

RTF decodes to an Equation Editor ProgID adjacent to OLE activation and the same decoded object stream contains embedded PE bytes. This matches the Equation Editor exploit surface used by CVE-2017-11882 / CVE-2018-0802 documents, while requiring payload evidence to avoid flagging benign Equation references.
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.
ClamAV: Rtf.Dropper.Agent-7702133-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Rtf.Dropper.Agent-7702133-0
\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
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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off000007cf.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x7CF	427812 bytes
SHA-256: `789c54a68238149f9454c21f3e62c71c8ef3680733b08569b466b944ef1100dc`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis found candidate code region(s). Indicators: SC_GETPC_CALL Carved artifact entropy is 8.00, consistent with packed or encrypted content.

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