Malicious RTF — malware analysis report

Static analysis result for SHA-256 a50df7b0ea95b630…

MALICIOUS

RTF

334.8 KB First seen: 2021-07-07
MD5: e4f5239252761fff02edbab21262fe0e SHA-1: bfbfc7e62e52b296101a876bdc9e2aa9335c6af6 SHA-256: a50df7b0ea95b630fe1c6acf05ba204fe42d361dc9c7c1be0b5e8c21ab9b8189
280 Risk Score

Malware Insights

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

The RTF file contains multiple OLE objects, including composite monikers, and triggers ".objupdate" which are indicative of exploitation attempts. Specifically, the CVE-2017-8570 heuristic indicates the file is designed to drop and execute a script. The embedded artifact objdata_01_off0000735b.bin is flagged as a suspicious extracted artifact containing shellcode command strings.

Heuristics 8

  • Composite Moniker — CVE-2017-8570 (drops SCT script) critical CVE related CVE_2017_8570
    RTF \objdata decodes to OLE data containing the Composite Moniker — CVE-2017-8570 (drops SCT script) CLSID — the vulnerable control/moniker is embedded directly in the document's object stream, the delivery shape of this exploit. RTF objects auto-render when Word opens the file.
  • Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED
    RTF contains Composite Moniker CLSID in OLE object context, but no nearby scriptlet/SCT payload was confirmed. Treat as related moniker attack-surface evidence rather than proof of CVE-2017-8570 exploitation.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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 4 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000bac.bin rtf-objdata-decoded RTF \objdata at offset 0xBAC 59587 bytes
SHA-256: 2d7b95bc68e815a133851305783fc7ffa0e719856bf9b724f72e2386e7cac781
objdata_01_off0000735b.bin rtf-objdata-decoded RTF \objdata at offset 0x735B 59560 bytes
SHA-256: 1efa73a89a55aab8ca1bb62296ae419ee91d8afa4eded960fd3e359f7a7f812b
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered command string(s): WScript.Shell"")")
objdata_02_off000257e8.bin rtf-objdata-decoded RTF \objdata at offset 0x257E8 2632 bytes
SHA-256: a8e170497da15decc11753d202c99c86f7a7ffd2d52481e6b9c79a5403675379
objdata_03_off00026d8b.bin rtf-objdata-decoded RTF \objdata at offset 0x26D8B 12297 bytes
SHA-256: e8d4fe950caed6dcfde26f4b616825bbe11b93458425974b7d075167f675abf7