Exploiting Windows RPC to bypass CFG mitigation: analysis of CVE-2021-26411 in-the-wild sample

The general method of browser render process exploit is: after exploiting the vulnerability to obtain user mode arbitrary memory read/write primitive, the vtable of DOM/js object is tampered to hijack the code execution flow. Then VirtualProtect is called by ROP chain to modify the shellcode memory to PAGE_EXECUTE_READWRITE, and the code execution flow is jumped to shellcode by ROP chain finally. After Windows 8.1, Microsoft introduced CFG (Control Flow Guard)[1] mitigation to verify the indirect function call, which mitigates the exploitation of tampering with vtable to get code execution. ...

April 10, 2021 · 6 min · iamelli0t

CVE-2021-26411: Internet Explorer mshtml use-after-free

In January of this year, Google and Microsoft respectively published blogs revealing attacks on security researchers by an APT group from NK[1][2]. A vulnerability in Internet Explorer used in this attack was fixed as CVE-2021-26411 in Microsoft’s Patch Tuesday this month[3]. The vulnerability is triggered when users of the affected version of Internet Explorer access a malicious link constructed by attackers, causing remote code execution. Root cause analysis The POC which can trigger the vulnerability is shown below: ...

March 12, 2021 · 7 min · iamelli0t