MalwareUsed by 1 actor

WHIRLPOOL

WHIRLPOOL is a C-based utility used to create a TLS reverse shell. It accepts either a file-path argument or an IP-and-port argument. Mandiant observed it being used alongside the SEASPRAY and SEASIDE malware families in Barracuda Email Security Gateway (ESG) intrusions attributed to UNC4841. In the described tradecraft, SEASIDE, a trojanized Lua module for the Barracuda SMTP daemon (bsmtpd), monitors SMTP HELO/EHLO commands, decodes an encoded C2 IP address and port, and passes them to WHIRLPOOL to establish a reverse shell. SEASPRAY, another trojanized Barracuda ESG Lua module, can copy an email attachment to /tmp and execute WHIRLPOOL when the attachment filename contains a special value. Additional reporting cited in the content states that Whirlpool was employed in attacks targeting Barracuda ESG devices through exploitation of CVE-2023-2868, a vulnerability in the email attachment screening module, and that these attacks were attributed by Mandiant to UNC4841. The content does not provide standalone file-based indicators for WHIRLPOOL itself.

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THREAT ACTORS

Groups observed using it

1 distinct threat actor attributed by public researchers. Open in Mallory to see the full evidence chain and overlapping campaigns.

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UNC4841

“WHIRLPOOL is a C based utility used to create a TLS reverse shell… Mandiant has observed WHIRLPOOL being used alongside SEASPRAY and SEASIDE.”

via mandiant threat intelligencecloud.google.com

MITRE ATT&CK

Techniques & procedures

3 distinct techniques documented for this family, organized by ATT&CK tactic.

Execution

1 technique

T1059.004Unix ShellEvidence1

“WHIRLPOOL…establishes a reverse shell.” / “WHIRLPOOL is a C based utility used to create a TLS reverse shell.”

Stealth

1 technique

T1036MasqueradingEvidence1

“Infrastructure…hosting default, self-signed SSL temporary certificates…to masquerade their reverse shell traffic as legitimate communications…”

Command and Control

1 technique

T1071.003Mail ProtocolsEvidence1

“SEASIDE…monitors SMTP HELO/EHLO commands to receive an encoded C2 IP address and port…”

ACTIVITY FEED

Recent activity

2 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

2 SOURCESView more in app

optiv blogNews

Sep 20, 2023

Critical Vulnerabilities Affecting Prioritized Software and Services in August 2023

Whirlpool is a malware variant used to gain unauthorized access to Barracuda ESG appliances by exploiting a critical vulnerability, enabling attackers to maintain persistence and control over compromised devices.

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IOC matching

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Threat actor attribution1

Named campaigns wielding this family, with evidence pinned to each claim.

Exploited vulnerabilities

CVEs this family uses for access and lateral movement.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

MITRE ATT&CK mapping3

Every documented technique, ranked by evidence weight.

Researcher chatter

Reddit, Mastodon, and CTI community discussion around this family.

WHIRLPOOL