# Some Number Theory

03 Jun 2020*Let $x_n$ be the remainder when $x$ is divided by $n.$ Compute the sum of all positive integers that satisfy*

*Let $x_n$ be the remainder when $x$ is divided by $n.$ Compute the sum of all positive integers that satisfy*

*Evaluate $\displaystyle\int_1^\infty\frac{dx}{e^{x+1}+e^{3-x}}$. (Source: Putnam)*

Admittedly, this problem took me an embarrasingly long time to solve (3 hours). Nonetheless, I had fun playing with this particular integral.

For this particular problem, it actually turns out that a symmetric nature is *extremely* helpful in successfully integrating.

Full PoC w/ abitrary code execution: Link to Issue

Update: The vulnerability has been partially fixed; however, the patch unintentionally removes desired functionality as stated here.

Not too long ago, I was casually perusing my way through GitHub and found the Threadtear Java bytecode deobfuscator. For those of you who don’t know, I have a strong interest for Java bytecode-related projects — especially when deobfuscation and obfuscation are involved.

There’s a warning on the README.md of the repository which specifically informs the user it is possible to successfully execute arbitrary code through the deobfuscator for malicious purposes. So of course, I decided to take up the challenge and create a proof of concept of an ACE exploit in Threadtear.

Earlier today, I visited the Tigress C obfuscator website today (I haven’t for awhile) and it looks much nicer now ;). Anyways, something that particularly interested me was Tigress’s page on EncodeArithmetic. Since I, a maintainer of a Java bytecode obfuscator, am always looking for cool things to try, found the book they linked of interest.

Isolation. The fearful enemy.. the enemy who takes away the feeling of life. Together with COVID-19… a powerful couple which completely drains even the strongest of all purpose. Every day we spend in isolation is another day we spend our short lives doing nothing. However, a worthy opponent approaches! And that worthy opponent is… salted caramel ice cream! Oh, how salted caramel ice scream is so brave… it fights off the possessiveness of isolation and restores life to us all! Salted caramel ice cream is our true hero in these dark times.

Thank you for attending my TED talk. Have a good night folks!

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