Securing Linux systems and applications; understanding Linux security features.

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Protect Public Directories Linux

Just for a brief overview. I have a system that can generate invoices and has a login system for a user to generate his/her invoices. Lets say the platform resides at /platform and the invoices in ...
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41 views

Ordering of the PATH environment variable

Locally here on Ubuntu 14.04, my $PATH looks something like this: PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games" When I manually define the path for ...
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1answer
161 views

How long to re-seed /dev/urandom in a virtual machine?

I have read plenty about the distinction between /dev/random and /dev/urandom. I understand that the prevailing advice is to use /dev/urandom. The explanation - that 256 bits of 'proper' randomness ...
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5answers
207 views

VPN with client certificate via managed PKI - where did private key come from?

$company allows Mac users to request a client certificate via Symantec PKI to connect to their SSL VPN server. This process involves going to a specific Symantec website (has some sort of ID to ...
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1answer
35 views

accessing Desktop from Root directory [closed]

I was using aircrack-ng package in my ubuntu 15.04. This package works only under root privileges. Now I want to save .cap file on my desktop using airodump-ng package but everytime I do, it throws an ...
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1answer
64 views

openssh old version vulnerabilities

My Ubuntu 12.04LTS system currently offers OpenSSH_5.9p1 Debian-5ubuntu1.8, OpenSSL 1.0.1 14 Mar 2012. Besides being old, it does not allow me to use e.g. the option # PubkeyAcceptedKeyTypes ssh-rsa* ...
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1answer
72 views

Detect port scans on Linux (centos) [closed]

I have OSSEC installed on my hosts. I want to detect port scans and generate an alert in OSSEC. So, how can I detect these port scans? Is it possible reading iptables logs? Do you recommend some ...
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33 views

can sudoedit in below context be used to privilege escalate?

We can sudo without supplying a password! Matching Defaults entries for werkzeug on vwebhost: env_reset, mail_badpass, secure_path=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin ...
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147 views

Is that possible for Linux and windows machines to be infected with KeRanger ransomware?

According to theguardian The Transmission site offers the open source software that was infected with the ransomware called KeRanger malware, it's programmed to encrypt files on an infected personal ...
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1answer
62 views

Minimal working configuration for reasonable security in openssh on Linux [duplicate]

I want to connect from my laptop to home server (both run some Linux; notice I explicitly want my user to be able to become root, in order e.g. to install new software): the server has the following ...
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30 views

How to know who and when files and folders have been deleted in CentOS? [duplicate]

I have a dedicated web server and there is some files and folders have been deleted from my client's sub-domain accidentally and there are more than one user mange the client site. How to know who ...
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1answer
90 views

Block OS fingerprinting without using iptables?

I have a Linux machine connected to a Windows 98 PC on port 104. Now I want to block the OS fingerprinting using nmap for the windows 98 PC. I tried using iptables (blocking that particular port) but ...
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2answers
24 views

Privilege escalation if the privileged ID is known

If I know the ID of a group, whose privilege is higher than mine, is it possible for me to execute programs using that group ID? If so, how do I do it? If not, why not? Will appreciate all answers.
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2answers
114 views

Don't encrypt the hard drive, but make it impossible to change things without a password?

I recently bought an SSD drive and realized that my CPU (Celeron 1007U - has no AES instructions) cannot really keep up encrypting it and the SSD doesn't have hardware encryption built in. This made ...
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3answers
675 views

Did CVE-2016-2324 allowed remote code execution?

Let’s say I have this kind of code : // In revision.c char *path_name(const struct name_path *path, const char *name) // by design, name_path->len is a 32 bits int, but this doesn’t concern name { ...
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0answers
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using “mount -o bind” in chroot

I have to provide a few, reasonably complete, chrooted ssh accesses to a very small system where disk space is at a premium. I was considering doing something along the lines: mkdir -p newroot/usr ...
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2answers
176 views

Why should one bother encrypting the harddisk in linux if one can easily recover the root password?

If you have physical access to a machine, it's pretty straightforward to recover the root password thereby skipping the whole point of having an encrypted drive. Am I missing something here? EDIT: ...
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2answers
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How could hackers get access to directory after hacking Wordpress at LinuxMint.com?

I am sure many have seen the news of the hack at Linux Mint. The ISOs were changed on 20th Feb with backdoored ISOs. They gained access via the LinuxMint Wordpress blog installation. How could they ...
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1answer
54 views

What are the potential privacy issues in using a TPM chip with GNU/Linux

I'm planning to buy a TPM module to bring more security in my system (GNU/Linux, dm-crypt/LUKS, SED) but I'm not sure with the big debate around it. What are the (possible) privacy concerns in using ...
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1answer
517 views

GNU C Library getaddrinfo() Flaw

As you probably already know, this Tuesday a potentially catastrophic flaw has been identified on glibc function called getaddrinfo(), which performs domain name lookups, contains a buffer overflow ...
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1answer
74 views

Will installing a Graphical User Interface in a server be a security problem?

I'm not a CLI-lover, sometimes I prefer to do some tasks in a server using a GUI rather than using the CLI (it speeds up my work), but I don't know if installing a GUI and accessing it using VNC and ...
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1answer
114 views

What are the advantages and disadvantages of installing an operating system through network? [duplicate]

Netboot is a technology that allows a computer to boot through the network, instead of starting on a hard drive, USB stick or DVD, it connects to a remote server to retrieve a disk image to start. It ...
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1answer
205 views

Linux - user can be in forbidden directory if su to it from user with access - is this concerning?

I was in a directory on CentOS as user1 (root in this case) and then did su to user2 which cannot normally get to that directory due to lack of "execute" permission on a parent directory, but as user2 ...
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Is that a way break Linux user password by bypassing grub protected?

The best way to delve into others Linux machine is by editing the grub. Many will start by, editing the line ro quite splash as rw init=/bin/bash during the startup (usually by pressing button e on ...
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Where can i find information about Ipsec Xfrm framework?

I have searched online and found very little information about the ipsec xfrm framework, including the book Networking implementation and Theory.. Where can i get more information about xfrm ...
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2answers
120 views

A question about arpspoof command

The arpspoof command will spoof default_router_ip's MAC address on all victims in the subnet arpspoof -i <NIC> <default_router_ip> How does it fool the router about the MAC addresses ...
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1answer
54 views

Linux distribution on USB stick used to banking for begginers [closed]

Is it good idea to use up-to-date Linux on USB stick instead liveCD to online banking? What is the best Linux distribution for not advanced people who commonly use Windows to make online payments ...
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2answers
79 views

Making a file immutable (against kernel exploits)

I'd like to know how to make files completely immutable. "Completely" refers in this case to: immutable while the system is running. I could live with something like physical access where someone e.g ...
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32 views

OSSEC error “agent_control(1750): ERROR: No remote connection configured. Exiting”

I am new to OSSEC and trying to figure the tool to deploy it. I have an ubuntu server where I downloaded and installed the security onion packages. I have a few windows systems which I would like to ...
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1answer
52 views

Open Root File Using Other Users “.bashrc -> .profile” [closed]

If I have access to .bashrc -> .profile for another user which is owned by root with lrwxrwxrwx permissions How could I capture /root/flag.txt? It's a Live CD. Thanks
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1answer
31 views

rpm package info leak?

On Linux, rpm -qi <package-name> command would display the package info, which would contain information of build machine - Build Host :<host-name> Does this pose any security risk? Is ...
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112 views

IPtables Linux Firewall and IPsec traffic

Can iptables filter out incoming datagrams that are IPSec-tunneled packets going to port 25?
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Is cryptsetup luksFormat -y --cipher aes-xts-plain --key-size 512 /dev/sdax a insecure setup for luks [duplicate]

Is cryptsetup luksFormat -y --cipher aes-xts-plain --key-size 512 /dev/sdax insecure. If so why and what setup would be good for keeping corporate information safe?
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1answer
18 views

Linux equivalent to Windows WriteProtect key in the registry for a software based write blocker?

I unfortunately don't have access to a physical write blocker and am looking for a software based write blocker in Linux. In Windows this can be achieved by modifying the registry and setting a DWORD ...
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41 views

XCCDF check with SCE - Suse Linux Enterprise Server 11

I have written some compliance checks for Red Hat based systems with XCCDF. Some of my checks are OVAL definitions others are shell-scripts. It works great. The same checks don't work on an SLES 11 ...
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1answer
113 views

Linux responds to ARP requests for other interfaces - could this be a security vulnerability?

Linux responds to ARP requests on all interfaces by default. To explain, say you have this setup: Client 1 ---> [eth1] server [eth0] <--- Client 2 And the server's eth1 IP is 192.168.1.1 and ...
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1answer
56 views

Are Linux System Capabilities Considered Mandatory Access Controls?

DAC is not mandatory because access permissions are left up to the resource owner's discretion. Mandatory Access Control (Smack, SELinux, etc) administration can only be accomplished by a ...
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2k views

Should I use a second/dedicated IP address for SSH?

When running a public web server (e.g., with Apache), I've heard it's recommended to bind SSH to a second IP address, different from the one Apache is listening to. But for me it seems like this is ...
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1answer
236 views

samdump2 Error reading ControlSet: _RegOpenKey

I copied both SAM and SYSTEM files from my Windows7 OS, and then used this command to read the content of the SAM file samdump2 SAM SYSTEM > mdp_chiffres.txt, but i'm getting this error Error ...
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3answers
284 views

How to (further) ensure SSH security?

I set up my Linux Ubuntu machine as an SSH server through no-ip.com and it works great. Recently I discovered the command, sudo lastb -ad -F -w which outputs a log of the most recent failed SSH ...
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2answers
87 views

Linux kernel security bugs and hardening Ubuntu? [closed]

I recently read some article about the linux kernel having vulnerabilities, I can't recall exactly where. Being new to linux, do you guys have some references on how I should prevent remote access to ...
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1answer
136 views

Pros and cons of disabling TCP timestamps

So, lynis informs me that I should unset net.ipv4.tcp_timestamps. I know that's a bad thing because an attacker could figure out which updates that require restarting the machine I haven't applied, or ...
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2answers
121 views

Secure Android app development [closed]

I'm beginning with Android App development and I want to make sure that I'm taking the proper security precautions since most apps will handle sensitive data. What security precautions should be ...
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1answer
59 views

Is it safe to host passwordless web applications/software with web GUI in Virtual Machines

I have a Linux Mint Virtual Machine which I use quite a lot with my Windows host. I have lots of Software installed there (mostly with web GUI so I can access them from host easily). So I am ...
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2answers
79 views

Protecting account ssh keys from root

How can users ssh private keys be protected from root stealing and attempting to brute force them? I cannot use selinux as the vendor will not support the app when it's in use? Thanks
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1answer
99 views

Hacked debian server alternative boot

The server of a customer has been hacked last night. It is a standard debian distribution with mysql, apache and ssh for remote access. The way it has been hacked is very peculiar. The standard URL ...
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1answer
84 views

Can a brute force attack be certainly prevented on a unix/linux shell?

I've been getting kind of curious about computer security. I know brute force has been discussed a fair bit on Stack, but I want to elaborate a bit by asking, "Is it possible to /certainly/ stop ...
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1answer
290 views

Can I decrypt a DiskCryptor-encrypted hard drive using Veracrypt?

I have a hardrive I encrypted with DiskCryptor back when I was using Windows. Now that I have Linux I want to decrypt the hard drive but it turned out DiskCryptor is not available for Linux, whereas ...
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1answer
5k views

What is real-world impact of CVE-2016-0728 (Linux Kernel Vulnerability)

Today emerged report about another serious vulnerability in opensource world, CVE-2016-0728. It is local privilege escalation in Linux kernel 3.8+. What are the the possible real-world exploitation, ...
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109 views

Security implications of android rooting

I know this question has been asked many times, but I didn't see a clear answer to it from security experts, or it is from several years ago and things might have changed. My question is double: ...