Malicious RTF — malware analysis report

Static analysis result for SHA-256 f0b577d087fa55cb…

MALICIOUS

RTF

691.8 KB First seen: 2020-06-01
MD5: bb3ed419b54180c92e5be754f3fed082 SHA-1: e4469a4791e24a0af543899f1b67101b7a687cdc SHA-256: f0b577d087fa55cb914d6fdb66c8ec59bb59f37a94ca7e517aec40b1e3e1cab6
182 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains an embedded OLE object that exploits the CVE-2017-11882 vulnerability in Microsoft Equation Editor. This exploit is known to download and execute a second-stage payload, which is likely malicious. The extracted artifact 'objdata_00_off000007d5.bin' is the decoded payload from this exploit.

Heuristics 5

  • 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.
  • \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
  • 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.

FilenameKindSourceSize
objdata_00_off000007d5.bin rtf-objdata-decoded RTF \objdata at offset 0x7D5 353164 bytes
SHA-256: ea3ac8164b18cfc22389a7b0c52bea76195867d813a4d7b7542031672e0be424
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 8.00, consistent with packed or encrypted content.