Microsoft IIS | Breaking Cybersecurity News | The Hacker News

Cybersecurity researchers have discovered a remote denial-of-service exploit that affects major web servers, including NGINX, Apache HTTPD, Microsoft IIS, Envoy, and Cloudflare Pingora. The vulnerability has been codenamed HTTP/2 Bomb by Calif. "The vulnerable behavior exists in each server's default HTTP/2 configuration," the company said, adding it was discovered by OpenAI Codex by chaining together two known techniques: a compression bomb and a Slowloris -style hold. "The bomb targets HPACK, HTTP/2's header compression scheme: one byte on the wire becomes one full header allocation on the server, repeated thousands of times per request," Calif added. "The hold is a zero-byte flow-control window that keeps the server from ever freeing any of it." HPACK is a dedicated header compression algorithm for HTTP/2 used for compressing request and response metadata using Huffman encoding that results in an average reduction of 30% in header siz...

Microsoft Internet Information Services (IIS) is a web server software package designed for Windows Server. Organizations commonly use Microsoft IIS servers to host websites, files, and other content on the web. Threat actors increasingly target these Internet-facing resources as low-hanging fruit for finding and exploiting vulnerabilities that facilitate access to IT environments.  Recently, a slew of activity by the advanced persistent threat (APT) group Lazarus has focused on finding vulnerable Microsoft IIS servers and infecting them with malware or using them to distribute malicious code. This article describes the details of the malware attacks and offers actionable suggestions for protecting Microsoft IIS servers against them.  An Overview on Microsoft IIS Servers IIS was first introduced with Windows NT 3.51 as an optional package back in 1995. Since then, it has seen several iterations, improvements, and features added to align with the evolving Internet, includin...

The infamous Lazarus Group actor has been targeting vulnerable versions of Microsoft Internet Information Services ( IIS ) servers as an initial breach route to deploy malware on targeted systems. The findings come from the AhnLab Security Emergency response Center (ASEC), which detailed the advanced persistent threat's (APT) continued abuse of DLL side-loading techniques to run arbitrary payloads. "The threat actor places a malicious DLL (msvcr100.dll) in the same folder path as a normal application (Wordconv.exe) via the Windows IIS web server process, w3wp.exe," ASEC explained . "They then execute the normal application to initiate the execution of the malicious DLL." DLL side-loading , similar to DLL search-order hijacking, refers to the proxy execution of a rogue DLL via a benign binary planted in the same directory. Lazarus , a highly-capable and relentless nation-state group linked to North Korea, was most recently spotted leveraging the same t...