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Threat Brief: OWASSRF Vulnerability Exploitation
Unit 42 details active exploitation of Exchange SSRF flaws CVE-2022-41080/CVE-2022-41082 via the OWASSRF method, deploying the SilverArrow PowerShell backdoor.
Unit 42 documents OWASSRF, an exploit chain combining CVE-2022-41080 and CVE-2022-41082 to achieve remote code execution on Microsoft Exchange via Outlook Web Access, bypassing Microsoft's ProxyNotShell mitigations. Active exploitation was observed in late November and early December 2022, affecting at least eight organizations. Attackers authenticated to Exchange, then executed a PowerShell backdoor tracked as SilverArrow to create admin accounts, install AnyDesk, tunnel RDP via PuTTY Link, and dump LSASS memory for credential theft. Exploitation is isolated rather than mass-scale because authentication is required.
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New Mirai Variant Targeting Network Security Devices
New Mirai botnet variant exploits nine vulnerabilities in SonicWall, D-Link, Netgear, and other devices, with attacks ongoing at publication.
Unit 42 observed attacks exploiting VisualDoor (SonicWall SSL-VPN), CVE-2020-25506 (D-Link DNS-320), CVE-2020-26919 (Netgear ProSAFE Plus), and other flaws, with infrastructure rotating across at least three IP addresses between February 16 and March 13, 2021. Payloads were updated hours after CVE-2021-27561 and CVE-2021-27562 (Yealink Device Management, unauthenticated root RCE) and later added CVE-2021-22502 (Micro Focus Operation Bridge Reporter) and CVE-2019-19356 (Netis WF2419). Successful exploitation invokes wget to fetch shell scripts that download Mirai binaries compiled for multiple architectures and brute-forcers, and attacks were still ongoing when reported.
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