A thousand rubles, or about $34, was enough to bribe an airline agent to put a Chechen woman on board a flight just before takeoff, according to Russian investigators. The agent took the cash, and on a ticket the Chechen held for another flight simply scrawled, "Admit on board Flight 1047."

The woman was admitted onto the flight, while a companion boarded another plane leaving Moscow's Domodedovo Airport the same evening. Hours later, both planes exploded in midair almost simultaneously, killing all 90 people aboard.

A string of procedural breakdowns that let the two female suicide bombers board the planes last month brought home how deeply bribery, extortion and negligence are ingrained in Russia's security system. Many Russians consider their law enforcement authorities to be as crooked as the criminals they are supposed to catch.

Increasingly, the Chechen radicals who are targeting Russian civilians in a campaign to win independence for their southern province have learned to exploit that weakness to devastating effect. President Vladimir Putin's failure to curb corruption in the security system, according to analysts and law enforcement veterans, has left the country vulnerable to more attacks and handicapped in its fight against the bombers and hostage takers who often slip someone a few rubles so they can operate with impunity.

"This has become the normal way of doing business in Russia," said Pavel Chikov, a leader of a group called Public Verdict, which fights police abuses and corruption. "It's not seen as weird behavior when someone gives bribes or takes bribes. That's normal."

Georgi Satarov, head of the Indem public policy analysis institute and an aide to Boris Yeltsin when he was Russia's president, said his group's annual survey of corruption found that the police were "absolutely corrupt and consequently absolutely not effective."

A History of Bribery

The plane bombers were hardly the first terrorists in Russia who have succeeded in part through under-the-table payoffs, lax security or the assistance of law enforcement agents. The band of guerrillas who stormed a school in the southern town of Beslan this month picked up a police officer along the way who helped them get through checkpoints, authorities have said. In the bloody denouement of the crisis, 338 children and adults were killed.

Authorities have acknowledged that a similar group of gunmen paid off police in 2002 as they transported a virtual armory of assault rifles, hand grenades and explosives all the way from the south to Moscow, where they seized a theater filled with patrons. The subsequent standoff left 129 hostages dead. "They admitted it," Satarov said. "But it was two years ago, and nothing has been done."

And it has been nine years since Shamil Basayev, the Chechen guerrilla leader, led an assault force that took over a hospital with more than 1,000 people in the southern city of Budennovsk. That attack ended with more than 100 civilian deaths. Basayev later told an interviewer that he had gotten past police road stops with $10,000 in bribes and had intended to go all the way to Moscow but stopped in Budennovsk because he ran out of money.

"I know Russia," he was quoted as saying in the newspaper Nezavisimaya Gazeta in 1996. "There are no problems. If you have good money, any cop will let you go, even from the scene of a crime -- provided you get caught, that is." Basayev later took credit for the theater siege, and he allegedly wrote a message on the Internet on Friday asserting responsibility for the Beslan school massacre.

President Putin has conceded that corruption in the security agencies has played a direct role in the string of terror attacks in Russia that have killed more than 1,000 people in the past two years. "We have let corruption affect the judicial and law enforcement sphere," he said in an address to the nation after the Beslan crisis.

In a speech Monday, Putin vowed to toughen punishment for "official crimes which at first sight look insignificant" but turn out to have "grave consequences." As an example, he cited an illegally granted passport eventually used by terrorists. "Sanctions," he said, "should be adequate to the effects of that crime."

But in the two weeks since the school massacre, Putin has offered no concrete plans for combating corruption, focusing instead on consolidating his political power by eliminating the election of governors and independent members of parliament.

Few Russians believe that Putin has done much to halt abuses after nearly five years in office, according to public opinion polls. Asked last fall about corruption and thievery among the country's leadership, 68 percent of those responding to a survey said it had stayed the same or grown worse during Putin's tenure, while 22 percent thought it had declined, according to the independent Yuri Levada Analytical Center.

The Fund for Public Opinion, the polling firm employed by the Kremlin, concluded in a survey that "Russians regard the police as a ruthless corporation focused on its own interests, which cares nothing about the people."

In a focus group conducted by the fund in the city of Voronezh last year, participants saw an unbreakable nexus between security agencies and personal profiteering.

"To my mind, there is a coalescence of police and corruption in our country," one participant said.

"People say, 'He who doesn't want to work becomes a policeman,' " added another.

"Today," the first responded, "they are nothing but legalized criminals."

Corruption has been pervasive in Russian life since the time of the czars and persists today. The traffic police, still known by their Soviet-era initials as GAI, remain infamous for stopping drivers and finding a small infraction or discrepancy, real or invented, on a document in order to extract bribes of 100 rubles, or about $3. Some drivers in Moscow get hit up several times in a single week and shrug it off as if it were a road toll.

Police have also been known to plant drugs on random people in the streets, particularly those who look as if they come from Chechnya or other places in the Caucasus; many men from the region sew up their pockets so that drugs cannot be stuffed inside.

Two young men were stopped by four police officers last winter in the city of Kazan and had drugs planted on them, according to the Human Rights Center in Kazan, a group that defends Russians against police abuses. The officers, according to the center, demanded 100,000 rubles, or more than $3,400, to let the two go, then sent one of the men off to get the money while holding the other hostage.

The man instead called the human rights center, which contacted the police internal affairs division and set up a sting in which the officers were arrested as soon as the man turned over 100,000 rubles in marked bills. "This kind of activity is pretty common around Russia," said Dmitri Kolbasin of the center. "This is an acute problem."

As last month's airplane bombings showed, airports are a regular source of illegal double-dealing by authorities.

A businesswoman calling herself Margarita recalled how she was pulled aside by security officers at an airport as she prepared to board a flight abroad with her 17-year-old granddaughter. The security agents insisted she did not have the right stamp on a document and demanded $300 to let them board. After reluctantly paying, Margarita and the girl were whisked through security and passport control without being stopped.

"It's disgusting," said Margarita, who spoke on the condition that her last name not be used. "The thing is that in Russia, we face such experiences every step we take."

Working the System

The two women who set out to destroy the planes evidently knew how to work the system. According to the account given by Prosecutor General Vladimir Ustinov, the women were stopped by airport police who considered them suspicious and turned them over to a captain in charge of anti-terrorism operations.

Ustinov said the police captain was supposed to "examine their belongings and check these people for their potential role in terrorist attacks" but instead "let them go without any check." Ustinov did not offer any explanation for the captain's actions.

The women then found a black-market ticket seller, who charged them 5,000 rubles, or about $171, to help them get onto two separate flights, Ustinov said. The black-market dealer obtained a ticket for one of the women to Volgograd. The other woman already had a ticket for the next day to Sochi, so a ticket agent exchanged that along with 1,000 rubles two minutes before passenger registration for the flight ended, Ustinov said.

Both the dealer and the Sibir airline agent who allegedly took the money have been arrested. Ustinov offered no further details about how the women smuggled explosives aboard. Based on passports they used, they have been identified as two Chechen women, Satsita Dzhebirkhanova and Aminat Nagayeva, but some Russian news reports have suggested those passports were fakes.

The circumstances stirred no great outrage after Ustinov's revelations. Nikita Petrov, a historian for the human rights group Memorial, who specializes in the history of the Soviet special services, said police corruption is so widely accepted that Russians no longer consider the consequences.

"People don't think that the state is disintegrating when police take bribes. They don't understand how this destroys the idea of rule of law and civil society," he said. "We understand that there are laws and there is life and that it is easier to pay a bribe than deal with the bureaucracy."

Satarov, the former Yeltsin aide, said corruption could not be reined in under Russia's current political system, in which Putin has systematically eliminated most political opposition. "Only with real political competition, freedom of speech and real transparency of the authorities -- only under these conditions where there is political and public control over bureaucracy is it possible to combat," he said. "It's hopeless under the current political conditions."

In this file photo, workers search the crash site of one of the planes downed in late August by Chechen bombers, who bribed their way onto the flights.