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<div class="Box position-absolute overflow-hidden d-none jump-to-suggestions js-jump-to-suggestions-container">



  • <span>No suggested jump to results</span>

</div>
</label>
</form> </div>
</div>

</div>

<div class="position-relative mr-lg-3 d-lg-inline-block">

Sign in

</div>


Sign up

</div>
</div>
</div>
</div>
</header>

</div>

<div id="start-of-content" class="show-on-focus"></div>

<div id="js-flash-container" data-turbo-replace>

<template class="js-flash-template">

<div class="flash flash-full {{ className }}">
<div class="px-2" >
<button autofocus class="flash-close js-flash-close" type="button" aria-label="Dismiss this message">
<svg aria-hidden="true" height="16" viewBox="0 0 16 16" version="1.1" width="16" data-view-component="true" class="octicon octicon-x">
<path d="M3.72 3.72a.75.75 0 0 1 1.06 0L8 6.94l3.22-3.22a.749.749 0 0 1 1.275.326.749.749 0 0 1-.215.734L9.06 8l3.22 3.22a.749.749 0 0 1-.326 1.275.749.749 0 0 1-.734-.215L8 9.06l-3.22 3.22a.751.751 0 0 1-1.042-.018.751.751 0 0 1-.018-1.042L6.94 8 3.72 4.78a.75.75 0 0 1 0-1.06Z"></path>
</svg>
</button>
<div aria-atomic="true" role="alert" class="js-flash-alert">

<div>{{ message }}</div>

</div>
</div>
</div>
</template>
</div>


<include-fragment class="js-notification-shelf-include-fragment" data-base-src="https://github.com/notifications/beta/shelf"></include-fragment>

<div
class="application-main "
data-commit-hovercards-enabled
data-discussion-hovercards-enabled
data-issue-and-pr-hovercards-enabled
>
<div itemscope itemtype="http://schema.org/SoftwareSourceCode" class="">
<main id="js-repo-pjax-container" >


<div id="repository-container-header" class="pt-3 hide-full-screen" style="background-color: var(--color-page-header-bg);" data-turbo-replace>

<div class="d-flex flex-wrap flex-justify-end mb-3 px-3 px-md-4 px-lg-5" style="gap: 1rem;">

<div class="flex-auto min-width-0 width-fit mr-3">

<div class=" d-flex flex-wrap flex-items-center wb-break-word f3 text-normal">
<svg aria-hidden="true" height="16" viewBox="0 0 16 16" version="1.1" width="16" data-view-component="true" class="octicon octicon-repo color-fg-muted mr-2">
<path d="M2 2.5A2.5 2.5 0 0 1 4.5 0h8.75a.75.75 0 0 1 .75.75v12.5a.75.75 0 0 1-.75.75h-2.5a.75.75 0 0 1 0-1.5h1.75v-2h-8a1 1 0 0 0-.714 1.7.75.75 0 1 1-1.072 1.05A2.495 2.495 0 0 1 2 11.5Zm10.5-1h-8a1 1 0 0 0-1 1v6.708A2.486 2.486 0 0 1 4.5 9h8ZM5 12.25a.25.25 0 0 1 .25-.25h3.5a.25.25 0 0 1 .25.25v3.25a.25.25 0 0 1-.4.2l-1.45-1.087a.249.249 0 0 0-.3 0L5.4 15.7a.25.25 0 0 1-.4-.2Z"></path>
</svg>

<span>
</span>
<span>/</span>

ctf-write-ups

<span></span><span>Public</span>
</div>

</div>

</div>

<div id="responsive-meta-container" data-turbo-replace>
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<nav data-pjax="#js-repo-pjax-container" aria-label="Repository" data-view-component="true" class="js-repo-nav js-sidenav-container-pjax js-responsive-underlinenav overflow-hidden UnderlineNav px-3 px-md-4 px-lg-5">


<div style="visibility:hidden;" data-view-component="true" class="UnderlineNav-actions js-responsive-underlinenav-overflow position-absolute pr-3 pr-md-4 pr-lg-5 right-0"> <details data-view-component="true" class="details-overlay details-reset position-relative">
<summary role="button" data-view-component="true"> <div class="UnderlineNav-item mr-0 border-0">
<svg aria-hidden="true" height="16" viewBox="0 0 16 16" version="1.1" width="16" data-view-component="true" class="octicon octicon-kebab-horizontal">
<path d="M8 9a1.5 1.5 0 1 0 0-3 1.5 1.5 0 0 0 0 3ZM1.5 9a1.5 1.5 0 1 0 0-3 1.5 1.5 0 0 0 0 3Zm13 0a1.5 1.5 0 1 0 0-3 1.5 1.5 0 0 0 0 3Z"></path>
</svg>
<span>More</span>
</div>
</summary>
<details-menu role="menu" data-view-component="true" class="dropdown-menu dropdown-menu-sw">
</details-menu>
</details></div>
</nav>

</div>

<turbo-frame id="repo-content-turbo-frame" target="_top" data-turbo-action="advance" class="">
<div id="repo-content-pjax-container" class="repository-content " >



<div class="clearfix container-xl px-3 px-md-4 px-lg-5 mt-4">
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<div class="file-navigation mb-3 d-flex flex-items-start">

<div class="position-relative">
<details
class="js-branch-select-menu details-reset details-overlay mr-0 mb-0 "
id="branch-select-menu"
data-hydro-click-payload="{"event_type":"repository.click","payload":{"target":"REFS_SELECTOR_MENU","repository_id":142745576,"originating_url":"https://github.com/0n3m4ns4rmy/ctf-write-ups/tree/master/Pico%20CTF%202018/freecalc","user_id":null}}" data-hydro-click-hmac="218c02d0680ed76cc9547f37f91c9e67e001f68bbf6a658e8bcd1d316f7ebff7">
<summary class="btn css-truncate"
data-hotkey="w"
title="Switch branches or tags">
<svg text="gray" aria-hidden="true" height="16" viewBox="0 0 16 16" version="1.1" width="16" data-view-component="true" class="octicon octicon-git-branch">
<path d="M9.5 3.25a2.25 2.25 0 1 1 3 2.122V6A2.5 2.5 0 0 1 10 8.5H6a1 1 0 0 0-1 1v1.128a2.251 2.251 0 1 1-1.5 0V5.372a2.25 2.25 0 1 1 1.5 0v1.836A2.493 2.493 0 0 1 6 7h4a1 1 0 0 0 1-1v-.628A2.25 2.25 0 0 1 9.5 3.25Zm-6 0a.75.75 0 1 0 1.5 0 .75.75 0 0 0-1.5 0Zm8.25-.75a.75.75 0 1 0 0 1.5.75.75 0 0 0 0-1.5ZM4.25 12a.75.75 0 1 0 0 1.5.75.75 0 0 0 0-1.5Z"></path>
</svg>
<span>master</span>
<span></span>
</summary>


<div class="SelectMenu">
<div class="SelectMenu-modal">
<header class="SelectMenu-header">
<span>Switch branches/tags</span>
<button class="SelectMenu-closeButton" type="button" data-toggle-for="branch-select-menu"><svg aria-label="Close menu" aria-hidden="false" role="img" height="16" viewBox="0 0 16 16" version="1.1" width="16" data-view-component="true" class="octicon octicon-x">
<path d="M3.72 3.72a.75.75 0 0 1 1.06 0L8 6.94l3.22-3.22a.749.749 0 0 1 1.275.326.749.749 0 0 1-.215.734L9.06 8l3.22 3.22a.749.749 0 0 1-.326 1.275.749.749 0 0 1-.734-.215L8 9.06l-3.22 3.22a.751.751 0 0 1-1.042-.018.751.751 0 0 1-.018-1.042L6.94 8 3.72 4.78a.75.75 0 0 1 0-1.06Z"></path>
</svg></button>
</header>

<input-demux data-action="tab-container-change:input-demux#storeInput tab-container-changed:input-demux#updateInput">
<tab-container class="d-flex flex-column js-branches-tags-tabs" style="min-height: 0;">
<div class="SelectMenu-filter">
<input data-target="input-demux.source"
id="context-commitish-filter-field"
class="SelectMenu-input form-control"
aria-owns="ref-list-branches"
data-controls-ref-menu-id="ref-list-branches"
autofocus
autocomplete="off"
aria-label="Filter branches/tags"
placeholder="Filter branches/tags"
type="text"
>
</div>

<div class="SelectMenu-tabs" role="tablist" data-target="input-demux.control" >
<button class="SelectMenu-tab" type="button" role="tab" aria-selected="true">Branches</button>
<button class="SelectMenu-tab" type="button" role="tab">Tags</button>
</div>

<div role="tabpanel" id="ref-list-branches" data-filter-placeholder="Filter branches/tags" tabindex="" class="d-flex flex-column flex-auto overflow-auto">
<ref-selector
type="branch"
data-targets="input-demux.sinks"
data-action="
input-entered:ref-selector#inputEntered
tab-selected:ref-selector#tabSelected
focus-list:ref-selector#focusFirstListMember
"
query-endpoint="/0n3m4ns4rmy/ctf-write-ups/refs"

cache-key="v0:1532854671.0"
current-committish="bWFzdGVy"
default-branch="bWFzdGVy"
name-with-owner="MG4zbTRuczRybXkvY3RmLXdyaXRlLXVwcw=="
prefetch-on-mouseover
>

<template data-target="ref-selector.fetchFailedTemplate">
<div class="SelectMenu-message" data-index="{{ index }}">Could not load branches</div>
</template>

<template data-target="ref-selector.noMatchTemplate">
<div class="SelectMenu-message">Nothing to show</div>
</template>

<div data-target="ref-selector.listContainer" role="menu" class="SelectMenu-list " data-turbo-frame="repo-content-turbo-frame">
<div class="SelectMenu-loading pt-3 pb-0 overflow-hidden" aria-label="Menu is loading">
<svg style="box-sizing: content-box; color: var(--color-icon-primary);" width="32" height="32" viewBox="0 0 16 16" fill="none" data-view-component="true" class="anim-rotate">
<circle cx="8" cy="8" r="7" stroke="currentColor" stroke-opacity="0.25" stroke-width="2" vector-effect="non-scaling-stroke" />
<path d="M15 8a7.002 7.002 0 00-7-7" stroke="currentColor" stroke-width="2" stroke-linecap="round" vector-effect="non-scaling-stroke" />
</svg>
</div>
</div>

<template data-target="ref-selector.itemTemplate">

<svg aria-hidden="true" height="16" viewBox="0 0 16 16" version="1.1" width="16" data-view-component="true" class="octicon octicon-check SelectMenu-icon SelectMenu-icon--check">
<path d="M13.78 4.22a.75.75 0 0 1 0 1.06l-7.25 7.25a.75.75 0 0 1-1.06 0L2.22 9.28a.751.751 0 0 1 .018-1.042.751.751 0 0 1 1.042-.018L6 10.94l6.72-6.72a.75.75 0 0 1 1.06 0Z"></path>
</svg>
<span>{{ refName }}</span>
<span>default</span>

</template>

<footer class="SelectMenu-footer">View all branches</footer>
</ref-selector>

</div>

<div role="tabpanel" id="tags-menu" data-filter-placeholder="Find a tag" tabindex="" hidden class="d-flex flex-column flex-auto overflow-auto">
<ref-selector
type="tag"
data-action="
input-entered:ref-selector#inputEntered
tab-selected:ref-selector#tabSelected
focus-list:ref-selector#focusFirstListMember
"
data-targets="input-demux.sinks"
query-endpoint="/0n3m4ns4rmy/ctf-write-ups/refs"
cache-key="v0:1532854671.0"
current-committish="bWFzdGVy"
default-branch="bWFzdGVy"
name-with-owner="MG4zbTRuczRybXkvY3RmLXdyaXRlLXVwcw=="
>

<template data-target="ref-selector.fetchFailedTemplate">
<div class="SelectMenu-message" data-index="{{ index }}">Could not load tags</div>
</template>

<template data-target="ref-selector.noMatchTemplate">
<div class="SelectMenu-message" data-index="{{ index }}">Nothing to show</div>
</template>

<template data-target="ref-selector.itemTemplate">

<svg aria-hidden="true" height="16" viewBox="0 0 16 16" version="1.1" width="16" data-view-component="true" class="octicon octicon-check SelectMenu-icon SelectMenu-icon--check">
<path d="M13.78 4.22a.75.75 0 0 1 0 1.06l-7.25 7.25a.75.75 0 0 1-1.06 0L2.22 9.28a.751.751 0 0 1 .018-1.042.751.751 0 0 1 1.042-.018L6 10.94l6.72-6.72a.75.75 0 0 1 1.06 0Z"></path>
</svg>
<span>{{ refName }}</span>
<span>default</span>

</template>

<div data-target="ref-selector.listContainer" role="menu" class="SelectMenu-list" data-turbo-frame="repo-content-turbo-frame">
<div class="SelectMenu-loading pt-3 pb-0 overflow-hidden" aria-label="Menu is loading">
<svg style="box-sizing: content-box; color: var(--color-icon-primary);" width="32" height="32" viewBox="0 0 16 16" fill="none" data-view-component="true" class="anim-rotate">
<circle cx="8" cy="8" r="7" stroke="currentColor" stroke-opacity="0.25" stroke-width="2" vector-effect="non-scaling-stroke" />
<path d="M15 8a7.002 7.002 0 00-7-7" stroke="currentColor" stroke-width="2" stroke-linecap="round" vector-effect="non-scaling-stroke" />
</svg>
</div>
</div>
<footer class="SelectMenu-footer">View all tags</footer>
</ref-selector>
</div>
</tab-container>
</input-demux>
</div>
</div>

</details>

</div>

<div class="Overlay--hidden Overlay-backdrop--center" data-modal-dialog-overlay>
<modal-dialog role="dialog" id="warn-tag-match-create-branch-dialog" aria-modal="true" aria-labelledby="warn-tag-match-create-branch-dialog-header" data-view-component="true" class="Overlay Overlay--width-large Overlay--height-auto Overlay--motion-scaleFade">
<header class="Overlay-header Overlay-header--large Overlay-header--divided">
<div class="Overlay-headerContentWrap">
<div class="Overlay-titleWrap">
<h1 id="warn-tag-match-create-branch-dialog-header" class="Overlay-title">Name already in use</h1>
</div>
<div class="Overlay-actionWrap">
<button data-close-dialog-id="warn-tag-match-create-branch-dialog" aria-label="Close" type="button" data-view-component="true" class="close-button Overlay-closeButton"><svg aria-hidden="true" height="16" viewBox="0 0 16 16" version="1.1" width="16" data-view-component="true" class="octicon octicon-x">
<path d="M3.72 3.72a.75.75 0 0 1 1.06 0L8 6.94l3.22-3.22a.749.749 0 0 1 1.275.326.749.749 0 0 1-.215.734L9.06 8l3.22 3.22a.749.749 0 0 1-.326 1.275.749.749 0 0 1-.734-.215L8 9.06l-3.22 3.22a.751.751 0 0 1-1.042-.018.751.751 0 0 1-.018-1.042L6.94 8 3.72 4.78a.75.75 0 0 1 0-1.06Z"></path>
</svg></button>
</div>
</div>
</header>
<div class="Overlay-body ">

<div data-view-component="true"> A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?
</div>

</div>
<footer class="Overlay-footer Overlay-footer--alignEnd">
<button data-close-dialog-id="warn-tag-match-create-branch-dialog" type="button" data-view-component="true" class="btn"> Cancel
</button>
<button data-submit-dialog-id="warn-tag-match-create-branch-dialog" type="button" data-view-component="true" class="btn-danger btn"> Create
</button>
</footer>
</modal-dialog></div>

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<div class="d-none d-sm-block">
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<div class="f4 mt-3 mb-3 d-sm-none"><span><span><span>ctf-write-ups</span></span></span><span>/</span><span><span>Pico CTF 2018</span></span><span>/</span>freecalc<span>/</span></div>

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<div class="Skeleton avatar avatar-user flex-shrink-0 ml-n1 mr-n1 mt-n1 mb-n1" style="width:24px;height:24px;"></div>
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<h2 class="sr-only">Git stats</h2>


</div>
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</div>
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Permalink

<div data-view-component="true" class="include-fragment-error flash flash-error flash-full py-2">
<svg aria-hidden="true" height="16" viewBox="0 0 16 16" version="1.1" width="16" data-view-component="true" class="octicon octicon-alert">
<path d="M6.457 1.047c.659-1.234 2.427-1.234 3.086 0l6.082 11.378A1.75 1.75 0 0 1 14.082 15H1.918a1.75 1.75 0 0 1-1.543-2.575Zm1.763.707a.25.25 0 0 0-.44 0L1.698 13.132a.25.25 0 0 0 .22.368h12.164a.25.25 0 0 0 .22-.368Zm.53 3.996v2.5a.75.75 0 0 1-1.5 0v-2.5a.75.75 0 0 1 1.5 0ZM9 11a1 1 0 1 1-2 0 1 1 0 0 1 2 0Z"></path>
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<div role="rowheader" class="flex-auto min-width-0 col-md-2 mr-3">
<span>exploit.py</span>
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<div role="gridcell" class="flex-auto min-width-0 d-none d-md-block col-5 mr-3" >
<div class="Skeleton Skeleton--text col-7"> </div>
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<div role="gridcell" class="color-fg-muted text-right" style="width:100px;">
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Original writeup (https://github.com/0n3m4ns4rmy/ctf-write-ups/blob/master/Pico%20CTF%202018/freecalc/exploit.py).