pyjail2

pyjail-2/chall.yaml

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+name: JailBreak 2
+categories:
+  - misc
+value: 125
+flag: bcactf{PyTH0n_M4st3R_Pr0veD}
+description: |-
+  The prison has increased security measures since you last escaped it. 
+  Can you still manage to escape?
+hints:
+  - What in python is evaluated to a number?
+files:
+  - src: ./main.py
+authors:
+  - Jack Crowley
+visible: true
+#TODO Deployment

pyjail-2/deploy.py

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+def sanitize(letter):
+    print("Checking for contraband...")
+    return any([i in letter.lower() for i in BANNED_CHARS])
+
+def end():
+    print("Contraband letters found!\nMessages Deleted!")
+    exit()
+
+BANNED_CHARS = "gdvxfiyundmn'~`@#$%^&.{}0123456789"
+flag = "bcactf{PyTH0n_M4st3R_Pr0veD}"
+
+print("Welcome to the prison's mail center")
+
+msg = input("\nPlease enter your message: ")
+
+while msg != "":
+    if sanitize(msg): 
+        end()
+
+    try:
+        x = eval(msg)
+        if len(x) != len(flag): end()
+        print(x)
+    except Exception as e:
+        print(f'Error occured: {str(e)}; Message could not be sent.')
+
+    msg = input("\nPlease enter your message: ")

pyjail-2/main.py

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+def sanitize(letter):
+    print("Checking for contraband...")
+    return any([i in letter.lower() for i in BANNED_CHARS])
+
+def end():
+    print("Contraband letters found!\nMessages Deleted!")
+    exit()
+
+BANNED_CHARS = "gdvxfiyundmnet/\\'~`@#$%^&.{}0123456789"
+flag = "REDACTED"
+
+print("Welcome to the prison's mail center")
+
+msg = input("\nPlease enter your message: ")
+
+while msg != "":
+    if sanitize(msg): 
+        end()
+
+    try:
+        x = eval(msg)
+        if len(x) != len(flag): end()
+        print(x)
+    except Exception as e:
+        print(f'Error occured: {str(e)}; Message could not be sent.')
+
+    msg = input("\nPlease enter your message: ")

pyjail-2/solve.md

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+# JailBreak 2
+
+Unlike the first JailBreak, this time the security measures banned numbers. However, this does not factor into the fact the both `True` and `False` are counted as 1 and 0 respectedly. Using the `bool` function, which when presented with a not empty argument evaluates to true, we can then do math to get the the needed ascii values, counting the `bool("a")` as 1.
+
+```
+locals()[chr(((bool("a")+bool("a")+bool("a")+bool("a")+bool("a"))*(bool("a")+bool("a")))**(bool("a")+bool("a"))+bool("a")+bool("a"))+chr(((bool("a")+bool("a")+bool("a")+bool("a")+bool("a"))*(bool("a")+bool("a")))**(bool("a")+bool("a"))+(bool("a")+bool("a")+bool("a")+bool("a"))*(bool("a")+bool("a")))+chr(((bool("a")+bool("a")+bool("a")+bool("a")+bool("a"))*(bool("a")+bool("a")))**(bool("a")+bool("a"))-bool("a")-bool("a")-bool("a"))+chr(((bool("a")+bool("a")+bool("a")+bool("a")+bool("a"))*(bool("a")+bool("a")))**(bool("a")+bool("a"))+bool("a")+bool("a")+bool("a"))]
+```