Questions tagged [centos]

CentOS is a free operating system distribution based upon the Linux kernel. It is derived entirely from the Red Hat Enterprise Linux (RHEL) distribution.

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ModSecurity won't apply rules - no error log entries [migrated]

I have a fresh installation of CentOS 8. I installed Apache 2.4.37 from the repo. Then installed the latest ModSecurity: dnf install mod_security -y Checked the installation dnf info mod_security ...
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28 views

SOC2 and the CentOS root user

One of our customers has the following requirement: according to SOC2 they need to block access to the CentOS root account. They mean any access, even with su root or sudo su. We have blocked the SSH ...
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1answer
43 views

ASLR doesn't work?

I have following code: #include <stdio.h> #include <stdlib.h> int main() { int *ptr1 = malloc(16); int val1 = 0x12345678; printf("stack: %p\nheap: %p\n", &...
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49 views

.htaccess File Changed - Question About Possible Breach Or Default Defense Mechanism

Today I got reports about one of my websites becoming inaccessible. I've come to learn that at the time we were under DDOS attack. After getting through that, the website started throwing a ...
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1answer
64 views

Can I test ssl connection locally with a valid certificate (CA) with local dns?

I have a wildcard valid certificate signed by Certificate Authority. Is it possible to test the https locally from the server without a registered DNS? My idea is to bind the domain name with 127.0....
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1answer
91 views

/var got mysteriously renamed in /var.1 on CentOS6 server [closed]

On one of our CentOS6 servers, /var got renamed to /var.1 tonight (around 3.24 am) and a new empty /var folder was created. Not surprisingly, it crashed soon after that. Circumstances: Over the ...
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3answers
369 views

How to scan a list of RPM files for publicly declared (CVE) vulnerabilities?

Couldn't find a reliable tool to scan a list of CentOS or RHEL RPM files for vulnerabilities (e.g. list CVEs found for each file). The goal is to scan the RPM files for vulnerabilities before they ...
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403 views

Whether the `resets received for embryonic SYN_RECV sockets` and `invalid SYN cookies received` shows attacks there?

In my CentOS, I use netstat -s to check my CDN node server network summary. [root@hkk10 ~]# netstat -s Ip: 26529370 total packets received 6121 with invalid addresses 0 forwarded 0 ...
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1answer
100 views

Java web app hosted in tomcat hanged for more than 10 min with logs containing powershell attack

We have a java web application running in tomcat which is hosted in AWS. The operating system used in the server is Centos. Today it become inaccessible for more than 10 minutes. When we got access, ...
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1answer
120 views

Exposure of /etc/ssh, risks?

I accidentally exposed the keys in /etc/ssh What is the risk? I think it will allow someone to impersonate the server and conduct MITM. Will it let someone SSH into the server? I think not because ...
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1answer
69 views

RHEL7 SSGv0.1 2.2.3 Unauthorized SUID/GUID executables

We are upgrading to RHEL 7.6. My Nessus scanner is giving me the following message: 2.2.3.c-d Mandatory Review Required: Find unauthorized SUID/GUID System Executables RHEL7 SSGv0.1 2.2.3 Unauthorized ...
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1answer
230 views

Why is autofs insecure?

I am hardening CentOS/RHEL 7.6. The hardening documents recommend disabling the automounter, "unless it is necessary." Why is autofs such a problem? One of the benefits of networking is a shared file ...
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73 views

Rationale for removing cronie-anacron

My Nessus scanner reports that I need to remove cronie-anacron. What is the rationale for this? The Nessus output is: 3.3.b(2) Disable Anacron checking that the anacron RPM package is not ...
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97 views

How do I create exceptions on Wazuh (OSSEC)?

I currently have a setup with OSSEC and AIDE running on our servers. We are currently receiving a daily alert for each agent when AIDE runs and changes audit.log. I want to make an exception for ...
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1answer
3k views

Is TLS 1.3 supported in Dovecot 2.3.4 and Postfix 3.3.2?

I would like to configure an email CentOS 7-based server to use TLS 1.3. Currently it uses TLS 1.2 for securing the SMTP and POP3 sessions. For SMTP I use Postfix software and for POP3 I use Dovecot ...
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1answer
101 views

Is it dangerous to keep permissions at 666 to member file on SELinux?

I just installed SELinux. I read a lot of tutorials but I am not very comfortable with SELinux. On CentOS help page , I can see that some files in /selinux/ are writable by other user : https://www....
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1answer
49 views

CentOS payload injection attempts? [duplicate]

My PHP logs have been flooding with seemingly random attempts to access scripts and software which isn't installed on my server. At first, All the attempts came from a single IP, I was using ...
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1answer
105 views

php-fpm.log shows a mass of unusual attempts to open primary script with random filenames [duplicate]

I recently happened to inspect my php-fpm.log and found a lot of suspicious activity that looks like malicious attempts to get access to my host. Here're some of the logs: [07-Oct-2018 22:01:31] ...
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2answers
1k views

OpenSSL Certificate Renewal with same keys and NO CSR

I have a Linux-based vendor-supplied virtual appliance that uses OpenSSL to manage certificates. The current server certificate is from Symantec so has to be replaced with a DigiCert. DigiCert is ...
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98 views

Disable SSLv3 in IPSec CentosOS

I have been told to shut down support to SSLV3 - TLS 1.0 - TLS 1.1 to all encrypted communications towards external web services. Now, I have an IPSec/CentOS gateway in front of my Data Center.How ...
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1answer
320 views

ModSecurity Rule 973338

ModSecurity blocked access due to the following: [msg "XSS Filter - Category 3: Javascript URI Vector"] [data "Matched Data: esrco found within ARGS:as_email:hearsesesrcool@yahoo.com"] [...
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2answers
259 views

How to build arbitrary Dockerfile Images Without Compromising Host

I'm building a server that will build images directly from Dockerfile: docker build -t arbitrarydocker . This docker file will be built on the same server as other client Dockerfiles, which may have ...
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3answers
299 views

Tor exit node as CentOS mirror

Today we saw traffic going from CentOS servers to a Tor exit node. This caused some raised eyebrows and led us to investigate what was going on. In the end it turned out that this exit node also acts ...
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1answer
394 views

How to acquire security advisory for CentOS?

I've been seeing security advisory number like CESA-2017:1842, and after search I could only find some of them in mailing list archives such as this. Is there a website like https://usn.ubuntu.com or ...
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1answer
541 views

Are there open by default ports with Centos 7's firewalld?

My Centos7 firewalld has TCP ports 8083, 8086, and 5000 open. I don't recall opening them, except for maybe 5000 when first learning about firewalld. Are there any ports that might come out of the ...
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3answers
3k views

How secure is ssh key-based authentication

I have a newly installed (and updated) Centos 7 server I use for testing. I implemented RSA key based authentication for ssh and set PermitRootLogin to without-password When I logged on this morning ...
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1answer
987 views

Does anybody know if CentOS have official support for OVAL definitions?

I saw it here that CentOS have no official support for OVAL security definitions(patch, vulnerabilities). Based on what I observe at oval.mitre.org, it looks like they don't even have a vulnerability ...
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1answer
962 views

Android pinning SSL handshake Exception after SSL renewal of website

i've an android app with ssl pinned it was working fine but after i've renewed the SSL now its throwing exception javax.net.ssl.SSLHandshakeException: java.security.cert....
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1answer
178 views

Impacts of running “./CA newca” command in /etc/pki/tls/misc/ when CA already exists

After accidentally running "./CA newca" from /etc/pki/tls/misc, I noticed a few files getting updated in /etc/pki/CA, and possibly more. But there weren't any prompts when running the command like ...
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1answer
1k views

FIPS 140-2 ready linux distribution

We're preparing for FIPS 140-2 project and trying to minimize the effort in the software space. So - is there FIPS 140-2 ready Linux distribution that you can just install and not even touch the ...
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1answer
336 views

SELinux related to fips 140-2?

I'm preparing a CentoOS based product for FIPS 140-2 level 2 certification and I have gone through the guides on enabling FIPS mode in RHEL Distros. Is SELinux somehow related to FIPS requirements? ...
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1answer
147 views

Buffer overflow process in my server(How detect rootkit)? [duplicate]

Today i'm update my web server on Cent OS 6 and like this if see top 2593 root 20 0 196m 5228 212 S 730.6 0.1 484:18.06 wjeackglrl 8648 bitrix 20 0 399m 85m 7580 R 42.5 2.2 0:23....
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1answer
102 views

Preventing Website Directory Listing

When my CentOS 7 Apache web server was compromised recently, which hosts multiple sites, a script was uploaded to one of the sites and then used to add files to any other sites on the server that had ...
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4answers
33k views

Privilege escalation using passwd file

If I have a world writeable /etc/passwd file on a system, how can I escalate my privileges to root? I am currently a underprivileged user. The underlying OS is CentOS 7.2 in case you are wondering I ...
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1answer
899 views

What Does This Command Do? Should i be worried?

So I was debugging my code when I see these few lines in my log: GET /cgi/common.cgi 302 8.015 ms - 23 GET /stssys.htm 302 2.928 ms - 23 GET / 200 134.922 ms - 9896 POST /command.php 302 33.826 ms - ...
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1answer
296 views

RFI - Is this possible even if you use an Application Server?

Since JBoss is acting as a middleware - Application Server - I was wondering if it's still possible to face with File Inclusion attacks.(?) The reason I was wandering so is that in such a case, no ...
18
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5answers
3k views

Stop large requests to my server (TOR)

I am being attacked right now from Tor nodes which are doing 404 requests to my HTTP server. It is from one IP but when i use the DROP iptables rule, it starts again from another IP in a matter of ...
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1answer
226 views

System-Level Network Security (Packet Classification and etc.) - SELinux and Libnftnl

I read that Libnftnl is a userspace library providing a low-level netlink programming interface to the in-kernel nf_tables subsystem and it uses NFTables. Since it's a kernel related topic, at the ...
14
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1answer
813 views

Determining httpd PHP Scripts with Auditd

Background I have an issue on my server where some hole is allowing malicious PHP files to be written to any world-writable directories beneath the web root. It is not currently causing any harm, as I ...
21
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2answers
7k views

Backdoor account in passwd file

Long story short I was making sure a web app didn't create a LFI vuln by attempting to open /etc/passwd with it. My first attempt to prevent LFI was unsuccessful and listed out the file, and I noticed ...
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2answers
91 views

To what extent are supplementary yum repositories certified by CentoOS?

I'm building something which uses libsodium and will run on Ubuntu and CentOS 7. Ubunutu has the libsodium-dev package, but CentOS doesn't seem to include it by default. I see instructions to use ...
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1answer
341 views

Apache: Can I revoke certain client certificate on certain subdomain only

I would like to know if we can make the client certificate valid for certain sub domain (Virtual Host). For example if I have two client certificate A, B. A is valid for subdomainX but not for ...
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2answers
168 views

Using CentOS, is it OK to encrypt copies of root directories and mount the encrypted copies in place of the original root directories?

I am using a CentOS running on a Cloud Hosted Virtual Machine. The cloud hosting service is Digital Ocean. The cloud hosted VM dose not allow you to use full hard disk encryption as it dose not ...
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2answers
56 views

Is secure to enable tools like git on shared server?

I want to know if there is a real security reason to not enable tools like git, WP-CLI or npm. I want to run a server (Centos/CPanel), but I want to be sure that enabling them would not be a risk. ...
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1answer
3k views

OpenSSL version 1.0.1e in CentOS 6 — Heartbleed Vulnerability

I was reading the Heartbleed vulnerability in the OpenSSL and in its official website, they have a list which mentioned that version 1.0.1 to 1.0.1f are affected, as shown in below pic. I have CentOS ...
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1answer
2k views

What's the motivation for excluing /usr/local/bin from root's PATH?

I just discovered that root's PATH on CentOS does not include /usr/local/bin. What's the rationale for this? I'm tempted to add it to the PATH but I don't know what vulnerabilities that might ...
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1answer
212 views

LFI Why would I not see a response

I have the below two vulnerable PHP code sections in 2 files. I found the sources of these in an anony access FTP backup file home.tar.gz. So I'm getting the content of /etc/passwd with the null byte ...
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2answers
180 views

DROWN CVE-2016-0800 Patch Missing on Centos 7

My security admin is worried that my OpenSSL version does not contain a patch for DROWN (cve-2016-0800). I ran a yum update and have installed the latest Centos 7 OpenSSL: openssl-1.0.1e-51.el7_2.5....
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2answers
275 views

Block requests containing URL of other websites

GET / HTTP/1.1" 200 166113 "-" "Mozilla/5.0 (compatible; dsada/2.0; +http://www.asd.com/search/asddd.html) I found this request repeated continuously in my logs. How can I prevent this (requests ...
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0answers
235 views

What's going on with connections to/from bluecoat?

I'm trying to track down a cause on an Internal Server Failure for an Apache server. The IP address changed recently, so I thought the crash might be related. A quick search of the old IP: $ sudo ...