Detects sample mentioned in the Dubnium Report

Hunt Hypothesis

The hypothesis is that the detected sample aligns with malicious activity attributed to the Dubnium group, potentially indicating initial compromise or reconnaissance. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate early-stage threats associated with this advanced persistent threat group.

YARA Rule

rule Dubnium_Sample_5
{

    meta:
        description = "Detects sample mentioned in the Dubnium Report"
        author = "Florian Roth"
        reference = "https://goo.gl/AW9Cuu"
        date = "2016-06-10"
        super_rule = 1
        hash1 = "16f0b05d5e8546ab1504b07b0eaa0e8de14bca7c1555fd114c4c1c51d5a4c06b"
        hash2 = "1feaad03f6c0b57f5f5b02aef668e26001e5a7787bb51966d50c8fcf344fb4e8"
        hash3 = "41ecd81bc7df4b47d713e812f2b7b38d3ac4b9dcdc13dd5ca61763a4bf300dcf"
        hash4 = "5246899b8c74a681e385cbc1dd556f9c73cf55f2a0074c389b3bf823bfc6ce4b"
        hash5 = "5f07b074414513b73e202d7f77ec4bcf048f13dd735c9be3afcf25be818dc8e0"
        hash6 = "839baf85de657b6d6503b6f94054efa8841f667987a9c805eab94a85a859e1ba"
        hash7 = "a25715108d2859595959879ff50085bc85969e9473ecc3d26dda24c4a17822c9"
        hash8 = "bd780f4d56214c78045454d31d83ae18ed209cc138e75d138e72976a7ef9803f"
        hash9 = "e0918072d427d12b43f436bf0797a361996ae436047d4ef8277f11caf2dd481b"

    strings:
        $s1 = "$innn[i$[i$^i[e[mdi[m$jf1Wehn[^Whl[^iin_hf$11mahZijnjbi[^[W[f1n$dej$[hn]1[W1ni1l[ic1j[mZjchl$$^he[[j[a[1_iWc[e[" fullword ascii
        $s2 = "h$YWdh[$ij7^e$n[[_[h[i[[[\\][1$1[[j1W1[1cjm1[$[k1ZW_$$ncn[[Inbnnc[I9enanid[fZCX" fullword ascii

    condition:
        uint16(0) == 0x5a4d and filesize < 9000KB and all of them
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

Microsoft Defender for Endpoint — Custom indicators / advanced hunting
Email Gateway — Attachment scanning
File Share Monitoring — Periodic scanning of shared drives
YARA CLI — Manual threat hunting on endpoints

This rule contains 2 string patterns in its detection logic.

References

False Positive Guidance

Scenario: A system administrator is performing a scheduled backup of the /etc directory using rsync to a remote server.
Filter/Exclusion: Exclude processes related to rsync or any backup tools when accessing system directories like /etc.
Scenario: A developer is using git to clone a repository containing a file named dubnium_report.txt as part of a code review process.
Filter/Exclusion: Exclude file names matching dubnium_report.* or any files associated with Git operations.
Scenario: A security analyst is running a manual forensic investigation using volatility to analyze a memory dump, and the tool identifies a file named after a known Dubnium sample.
Filter/Exclusion: Exclude processes related to volatility or any memory analysis tools during forensic investigations.
Scenario: A system update job using yum or apt installs a package that includes a file named after a Dubnium sample as part of a legitimate software update.
Filter/Exclusion: Exclude package management tools (yum, apt, dnf, etc.) when detecting files with names matching Dubnium samples.
Scenario: An IT admin is using ansible to deploy a configuration script that includes a file named after a Dubnium sample for testing purposes.
Filter/Exclusion: Exclude processes initiated by ansible or any configuration management tools when detecting files with Dubnium-related names.