PurpleFox botnet uses WebSockets for more secure C2 communication

CVE-2019-0808 is an elevation-of-privilege flaw in the Windows Win32k kernel component, which fails to properly handle objects in memory, allowing a local, low-privileged attacker to execute code in the kernel and take full control of the system (CVSS 3.1: 7.8, high impact on confidentiality, integrity and availability). It is triggered by a local attacker running crafted actions against vulnerable Win32k system calls; a public proof of concept based on the NtUserMNDragOver call path is available. Per the source data, affected products are Windows 7 and Windows Server 2008 (exact service-pack/version ranges are not specified in the data). The bug was one of two Win32k zero-days patched in the March 2019 Patch Tuesday, was being actively exploited in targeted attacks attributed to the FruityArmor and SandCat groups, and Microsoft followed with an out-of-band fix after Google disclosed the zero-day. It is listed in CISA KEV (added 2021-11-03, ransomware use unknown), and EPSS currently assigns roughly a 53% probability of exploitation within 30 days (99th percentile).

Do: Apply the March 2019 Microsoft security updates (or the out-of-band fix) for Windows 7 and Windows Server 2008, including Extended Security Updates for systems past the January 2020 end of support, per the CISA KEV required action. Prioritize shared/terminal and RDS hosts where low-privileged users log in, since successful exploitation grants kernel-level privileges, and review those systems for indicators of the FruityArmor/SandCat targeted intrusions. No reliable workaround is documented for this Win32k flaw, so patching is the primary mitigation.

An elevation of privilege vulnerability exists in the Windows kernel's Win32k component, which fails to properly handle objects in memory (an uninitialized-variable condition). A local attacker who can already execute limited code on a target machine can trigger the flaw to gain kernel-level execution and elevate to SYSTEM privileges, giving full control of the host. Affected platforms are Windows 7, Windows 8.1, Windows RT 8.1, Windows 10 1507 and 1607, and Windows Server 2008, 2012 and 2016. The bug was patched in Microsoft's December 2019 Patch Tuesday after being actively exploited as a zero-day, including in the WizardOpium campaign attributed to a North Korea-linked actor. It is listed in CISA's Known Exploited Vulnerabilities catalog (added 2022-01-10, with known ransomware use) and carries a high EPSS of 74.3%.

Do: Apply the December 2019 security updates (or later cumulative updates) from Microsoft per CISA's required action. Because Windows 7/8.1 and Server 2008/2012 are past end of support and Server 2016 support is winding down, prioritize migration to supported Windows versions. Hunt for signs of local privilege escalation and follow-on activity, since this bug was used as a zero-day and appears in ransomware attack chains.

CVE-2020-1054 is an elevation-of-privilege flaw (CWE-787, an out-of-bounds memory access) in the Windows kernel-mode driver (win32k), which fails to properly handle objects in memory. To exploit it, an attacker who can already log on to an affected Windows machine must run a specially crafted application, which triggers the memory-handling error and allows arbitrary code execution in kernel mode. Successful exploitation effectively yields full SYSTEM-level control of the host: the attacker can install programs, view, change or delete any data, and create new accounts with full user rights. Affected products per the CPE data are Windows 7, 8.1, RT 8.1, Windows 10 versions 1507 through 1909, and Windows Server 1803 and 1903. The flaw was fixed in Microsoft's May 2020 Patch Tuesday, a public DrawIconEx-based local privilege escalation PoC exists, EPSS is 54.2% (99th percentile), and CISA added it to the KEV catalog on 2021-11-03, confirming exploitation in the wild; related threat reporting around this CVE ties it to malware campaigns such as PurpleFox and Raspberry Robin, while ransomware use is listed as unknown.

Do: Apply Microsoft's May 2020 security updates (or any later cumulative update) to Windows 7, 8.1, RT 8.1, Windows 10 1507–1909, and Windows Server 1803/1903, per the CISA KEV required action; prioritize multi-user hosts such as RDS servers where low-privileged users can run code. For legacy systems that no longer receive updates (e.g., Windows 7/8.1 post-EOL), limit local logon and software-execution rights for untrusted users and monitor for local privilege escalation activity.

CVE-2021-1732 is a local elevation-of-privilege vulnerability (CWE-787, out-of-bounds write) in Microsoft's Win32k kernel driver, publicly characterized as an "offset confusion" in the Win32k ConsoleControl routine. It is triggered locally: a process with only low privileges can invoke the vulnerable Win32k functionality without any user interaction, causing a user-supplied offset/pointer to be mishandled in kernel mode and memory to be written out of bounds. An attacker who successfully exploits the flaw can execute code in the kernel and elevate to SYSTEM, gaining full control of the host — which makes it a valuable second-stage link in malware and ransomware chains. Any system running the affected Windows 10 releases (1803, 1809, 1909, 2004, 20H2) or Windows Server 2019/1909/2004/20H2 is exposed, though exploitation requires the attacker to already run code locally on the target. The flaw was fixed in Microsoft's February 2021 Patch Tuesday updates, was added to CISA's KEV catalog on 2021-11-03 with known ransomware use, and carries a very high EPSS score (78.4%, 100th percentile), indicating sustained exploitation pressure.

Do: Apply Microsoft's February 2021 (or later) Windows cumulative security updates to all affected Windows 10 and Windows Server systems, per vendor instructions — CISA's KEV listing requires federal agencies to patch. Prioritize hosts exposed to untrusted local users or already compromised by malware (e.g., ransomware or Raspberry Robin activity, which has used chained Windows LPEs), and hunt on unpatched hosts for signs of post-exploitation privilege escalation to SYSTEM.