Suramya's Blog : Welcome to my crazy life…

September 4, 2023

Mashing Enter can allow you bypass full disk encryption in certain scenarios

Filed under: Computer Security,Linux/Unix Related,My Thoughts — Suramya @ 12:30 PM

When folks think about hacking and people bypassing secure systems they have this mental image of folks writing complex code or physically reading the data byte by byte but that is not always true. Sometimes, it is as simple as just keeping the enter key pressed while the system is booting up. Yes, you read that right. A few days ago a vulnerability was found in a TPM-protected system that is configured to implement unattended unlocking for LUKS full disk encryption using RedHat’s Clevis and dracut software along with systemd.

Generally, a Linux computer using TPM-protected unattended disk encryption will still allow a user to view the output of the boot process and optionally manually enter a decryption password with the keyboard. This allows for situations where the computer fails to boot and needs someone to troubleshoot the startup process. While the unattended TPM unlocking is taking place, the user is still presented with the password prompt and an opportunity to enter input.

There’s a limited window of time before the TPM will unlock the disk and the boot process will proceed automatically to the login prompt, so how can we effectively fuzz this input opportunity? What if we could type faster than a human being? Using an Atmel ATMEGA32U4 microcontroller (such as you’d find in an Arduino Leonardo development board) we can emulate a keyboard that sends virtual keypresses at essentially the maximum rate that the computer will accept. The following short Arduino program sets up a Leonardo as a keyboard emulator:

#include "Keyboard.h"
void setup() {
void loop() {;

One second after being plugged in this program begins to simulate pressing the Enter key on a virtual keyboard every 10 milliseconds. This is about 10x faster than the usual keyboard repeat rate you’d get simply holding down a key, and Linux seems to recognise around 70 characters per second using this method, or one keypress approximately every 15 milliseconds.

Sending keypresses this fast quickly hits the maximum number of password entry retries, while keeping the system from unlocking the disk automatically due to password guess rate limiting, and systemd eventually gives up trying to unlock the disk. It takes a minute or two but the recovery action in this failure scenario is to give us a root shell in the early boot environment

The simplest way to address the most immediate problem: Add and rd.emergency=reboot to the kernel command line. This ensures that if anything fails during the early boot process the computer will reboot immediately rather than dropping into a root shell.

However, this goes to show us that the old statement about security is still absolutely valid: “Physical access is root access. You can’t spend thousands on protecting the cyber threat landscape and ignore physical security such that people can just walk up to your computer and stick things inside. That being said, having a physical security program doesn’t necessarily protect your from an insider threat so that is also something to keep in mind.

Source: Pulsesecurity: Mashing Enter to bypass full disk encryption with TPM, Clevis, dracut and systemd

– Suramya

August 29, 2023

Excel holding up the Global Financial System, now with Python support

Filed under: Computer Security,Computer Software,My Thoughts,Tech Related — Suramya @ 1:12 PM

It is both impressive and scary how much of the world’s financial systems is being run using Microsoft Excel. Folks have created formulars/macros/scripts/functions etc in Excel that allows them to generate data that is used to take major financial decisions with real world impact.

In one of my previous companies we actually had a full discussion on how to get an inventory of all the Excel code in use at the company and how to archive it so that we have backups and version control on them. Unfortunately, I left before much headway was made but I did learn enough about excel use to scare me. (Especially since I am not the biggest fan of Microsoft software 😉 )

Now you might ask why so many people are using excel when there are better tools available in the market and these companies have inhouse teams to create custom software for the analyst and I asked the exact same questions when I started. I think it is probably because the tool makes it easy for folks to come up with formulas and scripts that get their work done instead of having to wait for an external team to make the changes etc that they need.

Now, a few days ago Microsoft made a surprise announcement that going forward they are going to support running Python inside an Excel file. Yikes!! In order to use this functionality you will need to be part of the Microsoft 365 Insider program and then you can type Python code directly into cells using the new =PY() function, which then gets executed in the cloud. From what I have read, this will be enabled by default and needs to be disabled via a registry key.

Since its inception, Microsoft Excel has changed how people organize, analyze, and visualize their data, providing a basis for decision-making for the millions of people who use it each day. Today we’re announcing a significant evolution in the analytical capabilities available within Excel by releasing a Public Preview of Python in Excel. Python in Excel makes it possible to natively combine Python and Excel analytics within the same workbook – with no setup required. With Python in Excel, you can type Python directly into a cell, the Python calculations run in the Microsoft Cloud, and your results are returned to the worksheet, including plots and visualizations.

We already have issues with Excel Macros being used as vectors for malware & viruses, this just opens a whole new front in that war. Now, admins will have to worry about attackers using Python in Excel to infiltrate the organization or to send data outside the org. I can see how it is useful for people working with datasets and MS is adding this functionality to keep up with other tools such as Tableau etc which are more powerful but still I feel that this is a bad move.

Another problem that folks are going to face is that now your Excel sheets have Python programs inside them, how are we supposed to version the code, how is code review done? Basically this code should be going through the standard SDLC (Software Development Life Cycle) process but wouldn’t. We also need to ensure that all changes are reviewed and monitored to protect against insider attacks but the way the system is setup this is going to be extremely difficult (We have already seen that with Macros and Formulas etc).

Lets see how folks address this risk profile.

– Suramya

June 20, 2023

It is now possible to track someone using SMS Receipt Messages

Filed under: Computer Security,Interesting Sites,My Thoughts,Tech Related — Suramya @ 6:04 PM

With modern technology it is getting more and more easy to track someone. There are many apps, devices etc that allow a target to be tracked in near realtime by someone. This can be done using an App on your phone, find my phone functionality, family phone track etc etc. As someone who is worried about getting tracked they can disable GPS, get a new dumb phone that doesn’t support GPS etc which can mitigate the threat to a large extent. Unfortunately, now there is a new attack surface that allows an attacker to approximately locate a target with up to 96% accuracy.

Researchers have figured out how to deduce the location of an SMS recipient by analyzing timing measurements from typical receiver location. Basically they measure the time elapsed between sending a SMS and the receipt of the Delivery report and then use a ML model to predict the location area where the target could be located. The other advantage of this attack is that it doesn’t require any specialized equipment or access to restricted systems but can be executed via a simple smartphone.

Short Message Service (SMS) remains one of the most popular communication channels since its introduction in 2G cellular networks. In this paper, we demonstrate that merely receiving silent SMS messages regularly opens a stealthy side-channel that allows other regular network users to infer the whereabouts of the SMS recipient. The core idea is that receiving an SMS inevitably generates Delivery Reports whose reception bestows a timing attack vector at the sender. We conducted experiments across various countries, operators, and devices to show that an attacker can deduce the location of an SMS recipient by analyzing timing measurements from typical receiver locations. Our results show that, after training an ML model, the SMS sender can accurately determine multiple locations of the recipient. For example, our model achieves up to 96% accuracy for locations across different countries, and 86% for two locations within Belgium. Due to the way cellular networks are designed, it is difficult to prevent Delivery Reports from being returned to the originator making it challenging to thwart this covert attack without making fundamental changes to the network architecture.

The biggest problem with this method is that it doesn’t depend on any software or anything that needs to be installed on the target phone. You just need a phone that supports SMS, which is pretty much all phones in the market. There is an option to disable delivery reports which would mitigate the threat to an extent but is an opt-out setup rather than an opt-in. One way to reduce this vector would be for manufacturers to disable the delivery report by default and folks who need it can enable it from settings instead of the other way round which is the case right now.

Source: HackerNews: Freaky Leaky SMS: Extracting user locations by analyzing SMS timings
Full Paper: Freaky Leaky SMS: Extracting User Locations by Analyzing SMS Timings

– Suramya

June 12, 2023

A DIY Robot for automating a Cold boot attack now exists

Filed under: Computer Hardware,Computer Security,My Thoughts,Tech Related — Suramya @ 11:58 PM

A Cold boot Attack has been around for a while (It was first demo’d in 2008) but it has been a fairly manual tricky operation till now. But now there is a new DIY Robot has been created that reduces the manual effort for this attack. Now you might be asking what on earth is a Cold Boot Attack? No, it is not referring to having to wear cold shoes in winter. It is actually a very interesting attack where the attacker freezes the RAM chips of a system while it is running and then shuts it down, after which they remove the RAM chip and put it in another device to read the data from it. Because the chip has been cooled significantly it retains the information even after the system is shutdown long enough for information to be extracted from it. The original cold boot attack involved freezing a laptop’s memory by inverting a can of compressed air to chill the computer’s DRAM to around -50°C so that it persists for several minutes, even after the system was powered down.

Ang Cui, founder and CEO of Red Balloon Security has created a process & robot to extract the chip from the system. The robot is a CNC machine which is has a FGPA (field-programmable gate array) connected to it. The robot chills the RAM chips one at a time, extracts them from the board and then inserts them into the FGPA that reads the contents of the chip allowing them to extract the data from it. To make it easier and allow them more time to remove the chip, the system monitors the electromagnetic emanation of the device which allows them to identify when the system is running CPU bound operations. Once they identify that, they can extract the chip when the system is using the CPU and not reading/writing to the RAM. This gives the robot a window of ~10 milliseconds to extract the chips instead of having to do it in nanoseconds.

Cui and colleagues demonstrated their robot on a Siemens SIMATIC S7-1500 PLC, from which they were able to recover the contents of encrypted firmware binaries. They also conducted a similarly successful attack on DDR3 DRAM in a CISCO IP Phone 8800 series to access the runtime ARM TrustZone memory.

They believe their technique is applicable to more sophisticated DDR4 and DDR5 if a more expensive (like, about $10,000) FPGA-based memory readout platform is used – a cost they expect will decline in time.

Cold boot attacks can be countered with physical memory encryption, Cui said.

This is not an attack the average user has to worry about but it is something that folks working on critical systems like banking servers, government systems, weapons etc need to be aware of and guard against. More details on the attack will be provided during a talk at the REcon reverse engineering conference in Canada titled “Ice Ice Baby: Coppin’ RAM With DIY Cryo-Mechanical Robot

Source: Hacker News: Robot can rip the data out of RAM chips

– Suramya

May 19, 2023

KeePass exploit helps retrieve cleartext master password – Fix ETA July 2023

Filed under: Computer Security,My Thoughts,Tech Related — Suramya @ 8:06 PM

Security is hard to do and no matter how careful you are while coding every software will have bugs in it and some of these bugs have major security implications. Keepass which is a very popular password manager is vulnerable to extracting the master password from the application’s memory, allowing attackers who compromise a device to retrieve the password even with the database is locked. The bug is being tracked as CVE-2023-32784.

The issue was discovered by a security researcher known as ‘vdohney’ who has unfortunately also published PoC code that exploits the vulnerability called the “KeePass Master Password Dumper” on GitHub.

KeePass Master Password Dumper is a simple proof-of-concept tool used to dump the master password from KeePass’s memory. Apart from the first password character, it is mostly able to recover the password in plaintext. No code execution on the target system is required, just a memory dump. It doesn’t matter where the memory comes from – can be the process dump, swap file (pagefile.sys), hibernation file (hiberfil.sys), various crash dumps or RAM dump of the entire system. It doesn’t matter whether or not the workspace is locked. It is also possible to dump the password from RAM after KeePass is no longer running, although the chance of that working goes down with the time it’s been since then.

Tested with KeePass 2.53.1 on Windows (English) and KeePass 2.47 on Debian (keepass2 package). PoC might have issues with different encodings (languages), but that’s not confirmed as of now (see issue #3). Should work for the macOS version as well. Unfortunately, enabling the Enter master key on secure desktop option doesn’t help in preventing the attack.

The attack does require either physical access to the system or the system would need to be infected with Malware that give an attacker remote access with the ability to perform thread dumps. They can also extract the password from the process dump, swap file (pagefile.sys), hibernation file (hiberfil.sys) or RAM dump of the entire system.

The fix for the problem is in the works and the initial testing looks promising. Personally I think that the security researcher should have waited to release the PoC code till the fix is available but to each their own I guess.

Source: KeePass exploit helps retrieve cleartext master password, fix coming soon

February 20, 2023

Fixing SSL error 61 on Citrix Workspace on Debian

Was trying to connect to a Citrix Workspace and kept getting the following error “You have not chosen to trust “Entrust Root Certification Authority – XX”, the issuer of the security certificate (SSL error 61)“. I have hit this error in the past and had fixed it but couldn’t find my notes from how I had fixed it back then, so I had to resort to searching on the web based on vague memories of how I had fixed. After a bit of effort I found two solutions that people had suggested:

Solution 1:

Create a symbolic link pointing the /opt/Citrix/ICAClient/keystore/cacerts directory to /usr/share/ca-certificates/mozilla/ , using the command below as root:

mv /opt/Citrix/ICAClient/keystore/cacerts /opt/Citrix/ICAClient/keystore/cacerts.bak
ln -s /usr/share/ca-certificates/mozilla/ /opt/Citrix/ICAClient/keystore/cacerts 

Unfortunately, this didn’t resolve the problem for me.

Solution 2:

The second solution people recommended was to link /opt/Citrix/ICAClient/keystore/cacerts directory to the /etc/ssl/certs/ directory, using the command below as root:

mv /opt/Citrix/ICAClient/keystore/cacerts /opt/Citrix/ICAClient/keystore/cacerts.bak
ln -s /etc/ssl/certs/ /opt/Citrix/ICAClient/keystore/cacerts 

After I linked the directory to /etc/ssl/certs things immediately started working without errors. This time I am blogging about it so that the next time I don’t waste time trying to find the solution.

– Suramya

February 2, 2023

KeePass vulnerability that allows anyone with write access to the config file export all stored passwords

Filed under: Computer Security,Tech Related — Suramya @ 5:17 PM

Keepass is an Open source password manager that I have been using for a few years. For me the main attraction was that the password database is stored locally instead of using a cloud based solution. Although, you can configure it to save the password file on a cloud store if you want.

Recently a security ‘vulnerability’ has been found in KeePass that allows someone with access to the system where keypass is installed to export the entire password database to clear-text without any user intervention. Basically if an attacker has write access to the XML configuration file they can add an export trigger to get cleartext passwords as and when they are used. There is an ongoing dispute where it is being debated that this is technically not a vulnerability in KeePass as anyone with write access to the configuration file already has enough access to perform more powerful attacks. The issue has been assigned a CVE-2023-24055.

“In both cases, having write access to the KeePass configuration file typically implies that an attacker can actually perform much more powerful attacks than modifying the configuration file (and these attacks in the end can also affect KeePass, independent of a configuration file protection),” the KeePass developers explain. “These attacks can only be prevented by keeping the environment secure (by using an anti-virus software, a firewall, not opening unknown e-mail attachments, etc.). KeePass cannot magically run securely in an insecure environment.”

Personally, I think that while it does follow that physical access equals root access, there should be some notification / mechanism that gets triggered when the XML configuration file is modified outside the KeePass interface. Something like an alert that tells you that “The XML configuration file was directly modified. Please ensure that no extra triggers are installed” (or words to that effect). This way even if an attacker gets access to the system, they can’t easily get access to stored passwords would hopefully be protected with another password.

Source: Naked Security: Password-stealing “vulnerability” reported in KeePass – bug or feature?

January 17, 2023

I hacked the Tamil Nadu eGovernment site and all I got was this lousy blog post

Filed under: Computer Security,Computer Tips,Tech Related — Suramya @ 1:20 AM

Finally doing a writeup of how I found that the eGovernment portal of Tamil Nadu had a major bug with a huge privacy impact as it leaked user documents with sensitive information (Personally Identifiable
Information) to the public. This issue was reported and has been fixed as well so am sharing this information so that others are aware of this issue and help them avoid similar problems in sites they manage going forward.

This whole saga started when I had to apply for an epass to enter Tamil Nadu and noticed that the link sent to download the PDF copy of the pass did not require any password to access. The link to download the data was something like: where xxxxxx was a 6 character code. It looked like they might be vulnerable to an parameter enumeration attack so I wrote a quick script to try calling the URL with various sequential codes starting with AAAAAA and moving up. To my surprise within 30 seconds of me running the script I found another person’s personal document ( accessible over the web without any authentication. This URL gave me a PDF file that contained a “First Graduate Certificate” (Given to the first person in a family that graduates) for a lady in Virudhunagar District in Tamil Nadu.

Since I had proven that the private information was being leaked, I immediately killed the script and reported it to the Tamil Nadu CERT team using their web form and the same was also sent via email to on 12th March 2021.

A day later I got a call from the CERT team asking for more details. The lady I spoke with asked me a few questions about what I found and wanted additional information about me. The question she got stuck at was “Where are you currently working?” As I was on a work break since I doing my Degree in Cyber security I told her that I was not working anywhere but was a student. She was really confused and kept asking the question in different ways. After a few attempts she finally believed that I was studying Cyber Security and told me that they would look into this.

I expected them to take immediate action since this was a major privacy blunder but nothing happened and it was complete radio silence from them so I emailed them again a month later (29th April) asking for an update with another followup email sent in May with no response to either.

On 21st May I looped India CERT in the mail chain to escalate and wasn’t too hopeful of a quick response. Interestingly they replied within 24 hours asking for a PoC and screenshot of the issue, so I responded with a copy of the script I had written along with the PDF file containing the PII that I had found.

After that I didn’t get any communication from the team and I got busy with exams and classes so I didn’t follow up. However, every so often I would try to access the URL and it would still give me a PDF download. In October over 7 months after I first reported it I finally got an error when trying to download the data from the site. Now I get a 404 message stating that the page can’t be found. (The site gives too much detail in the error message but that is a different story and something for me to look at when I get some free time).

The overall experience was quite poor as in spite of the immediate response to the first notification of the issue they didn’t give me any details on the ETA for the fix or let me know once the issue was resolved. Which would have made it more streamlined and I wouldn’t have had to check frequently that the issue was resolved. If nothing else an email thanking for reporting the issue would have been nice, although I have seen that other agencies / sites giving bug bounty to people reporting such issues.

If you are hosting a site that allows users to generate data/files that can be downloaded the following should be kept in mind:

  • When creating links to the generated files, don’t use sequential ID’s for the files as it makes it easy to iterate through. Instead create long randomized strings for the ID’s to make them harder to guess
  • Add some form of authentication before allowing the download, something like a emailed link or SMS OTP to validate identity before allowing a download. For example the Nagaland Government site for ILP forces you to authenticate with an OTP before allowing you access to the document
  • Add some checks for bruteforce attempts to guess file paths and block them.

Well this is all for now. I have a few more of these that I will be sharing over the next few months once I verify that the issue is resolved and safe to disclose.

– Suramya

October 20, 2022

I am a Certified Threat Intelligence Analyst (CTIA) now

Filed under: Computer Security,My Life — Suramya @ 10:17 AM

I’m happy to share that I’ve obtained a new certification: CTIA (Certified Threat Intelligence Analyst) from EC-Council.

Certification Number Certification Name Issue Date Expiry Date
ECC8907421563 Certified Threat Intelligence Analyst October 17, 2022 October 16, 2025

With this I have completed 4 out of the 5 certifications I am eligible for after my degree in Cyber Security. The last one is CHFI and I will be attempting that shortly.

Well this is all for now, will write more later.

– Suramya

October 7, 2022

I am now a CEH (Certified Ethical Hacker)

Filed under: Computer Security,Linux/Unix Related,My Life — Suramya @ 6:23 PM

Gave my CEH (Certified Ethical Hacker) exam on 3rd Oct and have successfully cleared it.

Certification Number Certification Name Issue Date Expiry Date
ECC8907421563 Certified Ethical Hacker October 3, 2022 October 02, 2025

The exam was interesting and required a bit of memorization but over all not bad. I do wish they allow us to access the books or use the tools on the computer. I have a hard time remembering the parameters for commands and there were a few questions in there about what parameter would you use to do x. Normally I would do a man command before running it but here I had to remember the commands so it was a bit more annoying and required some extra effort to memorize, other than that the questions were great and required a lot of thinking and knowing the system.

Well this is all for now, will write more later.

– Suramya

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