Link to auto-downloaded DMG in encrypted zip
A link in the body of the message downloads an encrypted zip that contains a DMG file.
This technique has been observed ITW to deliver Meta Stealer, Atomic Stealer, and other MacOS malware.
Notably, in some instances, the attacker poses as a recruiter and initiates back and forth conversation with the recipient.
Sublime rule (View on GitHub)
1name: "Link to auto-downloaded DMG in encrypted zip"
2description: |
3 A link in the body of the message downloads an encrypted zip that contains a DMG file.
4
5 This technique has been observed ITW to deliver Meta Stealer, Atomic Stealer, and other MacOS malware.
6
7 Notably, in some instances, the attacker poses as a recruiter and initiates back and forth conversation with the recipient.
8type: "rule"
9references:
10 - "https://www.sentinelone.com/blog/macos-metastealer-new-family-of-obfuscated-go-infostealers-spread-in-targeted-attacks/"
11 - "https://www.virustotal.com/gui/file/38c907b0d7866bd73308535847f84b491a1adc39ab7cf0e06f3d535f0388560c/community"
12 - "https://www.malwarebytes.com/blog/threat-intelligence/2023/11/atomic-stealer-distributed-to-mac-users-via-fake-browser-updates"
13severity: "high"
14source: |
15 type.inbound
16 and any(body.links,
17 any(ml.link_analysis(.).files_downloaded,
18 any(file.explode(.),
19 (
20 any(.flavors.yara, . == "encrypted_zip")
21 and any(.scan.zip.all_paths,
22 any([".dmg"], strings.ends_with(.., .))
23 )
24 )
25 )
26 )
27 )
28 and (
29 profile.by_sender().prevalence != "common"
30 or (
31 profile.by_sender().any_messages_malicious_or_spam
32 and not profile.by_sender().any_messages_benign
33 )
34 )
35
36 // negate highly trusted sender domains unless they fail DMARC authentication
37 and not (
38 sender.email.domain.root_domain in $high_trust_sender_root_domains
39 and coalesce(headers.auth_summary.dmarc.pass, false)
40 )
41tags:
42 - "Malfam: MetaStealer"
43 - "Malfam: AtomicStealer"
44attack_types:
45 - "Malware/Ransomware"
46tactics_and_techniques:
47 - "Encryption"
48 - "Evasion"
49 - "Social engineering"
50detection_methods:
51 - "Archive analysis"
52 - "File analysis"
53 - "Sender analysis"
54 - "URL analysis"
55 - "YARA"
56id: "43af98d3-fa3e-5734-9f5b-61f07bc3eae1"