Apache Warns of Zero-Day Exploit in the Wild — Patch Your Web Servers Now!
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2021-41773 +1 in the same advisory: …41524 | Path Traversal to RCE in Apache HTTP Server 2.4.49 Apache HTTP Server contains a path traversal flaw (CWE-22) that lets crafted HTTP requests reach files outside directories configured via Alias-like directives. When files outside those aliased directories are not protected by the default 'require all denied' policy, attackers can read arbitrary files outside the intended root, and if CGI scripts are enabled the traversal can be escalated to remote code execution under the web server account. Anyone running an affected Apache HTTP Server release with such a configuration is exposed; the initial 2.4.50 patch was incomplete, so the flaw's full remediation is tracked under CVE-2021-42013. Exploitation is confirmed in the wild: CISA added the vulnerability to the KEV catalog on 2021-11-03 with known ransomware use, and EPSS assigns a ~100% probability of exploitation within 30 days (100th percentile). Do: Upgrade to Apache HTTP Server 2.4.51 or later; do not stop at 2.4.50, since its fix was incomplete (see CVE-2021-42013). As an interim mitigation, ensure directories referenced by Alias-like directives are covered by 'require all denied' and disable or restrict CGI (mod_cgi/mod_cgid) on traversable paths. Review access logs for traversal patterns such as /icons/../ and unexpected CGI invocations, and hunt for webshells or ransomware staging given the known ransomware use. | 9.8 group max | 100% | KEV ransomware PoC ×6 |
| masson the order of 100,000+ internet-exposed Apache servers |
Full article336 words · extracted from thehackernews.com · click to collapse
Ravie LakshmananOct 05, 2021
Apache has issued patches to address two security vulnerabilities, including a path traversal and file disclosure flaw in its HTTP server that it said is being actively exploited in the wild.
"A flaw was found in a change made to path normalization in Apache HTTP Server 2.4.49. An attacker could use a path traversal attack to map URLs to files outside the expected document root," the open-source project maintainers noted in an advisory published Tuesday.
"If files outside of the document root are not protected by 'require all denied' these requests can succeed. Additionally this flaw could leak the source of interpreted files like CGI scripts."
The flaw, tracked as CVE-2021-41773, affects only Apache HTTP server version 2.4.49. Ash Daulton and cPanel Security Team have been credited with discovering and reporting the issue on September 29, 2021.
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| Source: PT SWARM |
Also resolved by Apache is a null pointer dereference vulnerability observed during processing HTTP/2 requests (CVE-2021-41524), thus allowing an adversary to perform a denial-of-service (DoS) attack on the server. The non-profit corporation said the weakness was introduced in version 2.4.49.
Apache users are highly recommended to patch as soon as possible to contain the path traversal vulnerability and mitigate any risk associated with active exploitation of the flaw.
Update: Path Traversal Zero-Day in Apache Leads to RCE Attacks
The actively exploited Apache HTTP server zero-day flaw is far more critical than previously thought, with new proof-of-concept (PoC) exploits indicating that the vulnerability goes beyond path traversal to equip attackers with remote code execution (RCE) abilities. Security researcher Hacker Fantastic, on Twitter, noted that the vulnerability is "in fact also RCE providing mod-cgi is enabled."
Will Dormann, vulnerability analyst at CERT/CC, corroborated the findings, adding "I was not doing anything clever other than just reproducing essentially the public PoC on Windows when I saw calc.exe spawn."
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